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Full text of "Photomicrographs of iron and steel"

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PHOTOMICROGRAPHS 
OF IRON AND STEEL 



PHOTOMICROGRAPHS 

OF 

IRON AND STEEL 



BY 

EVERETT L. gEED, S.B. 

Instructor in Metallurgy in Harvard University 



WITH A FOREWORD BY 

Dr. ALBERT SAUVEUR 

Gordon McKay Professor of Metallurgy and Metallography 
in Harvard University 



NEW YORK 

JOHN WILEY & SONS, Ino. 

London: CHAPMAN & HALL, Limited 
1929 



Tti 

17 
H57 



Copyright, 1929, 
By EVERETT L. REED 



Printed in U. S. A. 

Printing Composition and Plates Binding 

1. GILSON CO. TECHNICAL COMPOSITION CO. STANHOPE BINDEST 

BOSTON CAMBRIDGE BOSTON 



23^ 



FOREWORD 

It is with great pleasure that I comply with the author's re- 
quest for a brief introduction to his excellent collection of photo- 
micrographs illustrative of the microstructure of steel in its 
many aspects. That there should be a need of such is an evi- 
dence of the widespread interest taken in metallography. It is 
of special significance to me and a source of gratification because 
of the part it was my good fortune to play at a time when metal- 
lography was indulgently regarded as a harmless and useless 
occupation. That was in the early nineties — frequently mis- 
named the gay nineties, if we consider the troubles we had and 
our difficulties in overcoming the indifference, if not the hostility, 
of the metallurgical world. 

To the best of my knowledge the first photomicrographs of 
steel taken in the United States were obtained in 1892 in the 
laboratory of the Illinois Steel Company at South Chicago, 
necessarily with scanty and crude equipment. All credit to the 
late and much regretted W. R. Walker, at the time Manager of 
the South Works, who had the foresight and the courage to di- 
rect that the structure of steel be studied under the microscope, 
following the methods described by Sorby in his masterful — 
epoch making — contributions to the Iron and Steel Institute 
in 1886 and 1887 and the work which had then just been started 
in France by Osmond and Le Chatelier and in Germany by 
Martens. Let us sing his praise and rejoice that a steel metal- 
lurgist lived at the time possessing the necessary imagination and 
independence of thought to leave the ruts where others continued 
to flounder. Walker took great interest in this study and was 
satisfied with the progress made; it covered a period of about 
four years, when a hurricane struck the South Chicago Works — 
in the form of a new president — which in its violence carried 
away the metallographical laboratory and its occupants. 

Following unsuccessful attempts to interest other steel makers 
in the use of the microscope, I decided to continue the Work in- 

iii 

14-057 



IV FOREWORD 

dependently through the opening in Boston of some commercial 
laboratories in 1896 and more especially through the publication 
of a quarterly magazine, The Metallographist. The latter was 
an audacious thing, as I look at it now in my more matured age, 
for a young man to attempt single-handed. So many kind words 
have been spoken, however, about the part played by this pub- 
lication in creating an interest in metallography and in contribu- 
ting to its progress that I am glad now that I did not have at the 
time the wisdom and prudence to keep me from an undertaking 
in appearance so hazardous. 

Today, it is no longer necessary to justify metallographic 
research. Indeed advance in metallurgy and even daily opera- 
tions are now hardly conceivable without the use of the micro- 
scope. 

While we may look with some complacency on the work ac- 
complished during the last thirty years, we realize also how much 
there is still to be done, how many problems are awaiting their 
solutions, how much there is in the behavior of steel which re- 
mains unexplained or but imperfectly understood. 

Younger metallurgists have a large task before them, worthy 
of their best efforts and promising of rich reward. It is in part 
to help them that the author has prepared this set of representa- 
tive structures. I welcome the opportunity it affords me of 
placing on record the affectionate regard in which I hold the 
author and my appreciation of his invaluable cooperation over a 
period of many years. 

Albert Sauveur 

Harvard University, 
August 16, 1928. 



PREFACE 

This little volume contains a set of photomicrographs of iron 
and steels some of which have been subjected to mechanical and 
thermal treatments according to standard practice. It is the 
author's hope that they may prove of assistance to those inter- 
ested in the production, in the treatment, and in the use of these, 
the most important of industrial metals. The heat treatments 
applied have generally been those recommended by the Society 
of Automotive Engineers. 

A list of iron and steels from which these photomicrographs 
were taken is given below : — 

1. Pure iron 

2. Commercial iron 

3. Wrought iron 

4. Cast steel 

(a) Annealed cast steel 

5. Hot-rolled steel 

6. Cold-rolled steel 

(a) Annealed cold-rolled steel 

7. A. Hot-rolled steel subject to recommended heat treatments 

(a) Annealed steel 

(6) Normalized steel 

(c) Hardened steel 

(d) Hardened and tempered steel 

(e) Hardened and drawn steel 

B. Hot-rolled steel subjected to the following miscellaneous 
heat treatments: 

(a) Steels heat treated according to the Metcalf test 

(b) Graphitizing of cementite 

(c) Spheroidizing of cementite 

(d) Overheating and burning 

(e) Grain growth in mild steel 

8. Case-hardened carbon steel 

(a) Heat treated case-hardened carbon steel 



VI PREFACE 

9. Decarburized steel 

10. Alloy steel subjected to recommended heat treatments. 

(a) Nickel 

(b) Chromium 

(c) Nickel-chromium 

(d) Chrome-vanadium 

(e) Molybdenum 

/) Manganese 
g) Silicon 

h) Silico-manganese 
i) Chrome-tungsten 
j) Non-scaling 

11. Case-hardened alloy steel subjected to recommended heat treat- 
ments. 

(a) Nickel 
(6) Chromium 

(c) Nickel-chromium 

(d) Molybdenum 

(e) Chrome-vanadium 

12. Nitrided steel 

13. Gray cast iron 

14. White cast iron 

15. Malleablized cast iron 

16. Semi-steel 

17. Chilled cast iron 

18. Cast iron containing special elements 

In developing the structure, the following reagents were used: 

A. FOR THE MICROSTRUCTURE 

1. 5% Nital — for all carbon steels, cast irons, and some alloy 
steels 

95 cc. absolute methyl alcohol to which 5 cc. of concen- 
trated nitric acid has been added. 

2. 1% Nital — Preparatory to the use of Kourbatoff's Reagent 
99 cc. absolute methyl alcohol to which 1 cc. of concen- 
trated nitric acid has been added. 



PREFACE VU 

3. Kourbatoff' s Reagent — High-speed Steels 

4 parts hydrochloric acid 
20 " iso-amyl alcohol 
75 " alcoholic solution of nitro-aniline 

4. Marble's Reagent — Stainless Steels 

4 grams copper sulphate 
20 " water 
20 " Con. hydrochloric acid 

5. Murakami's Reagent — Carbides and Tungstides in tung- 

sten and high-speed steels. 

10 grams potassium ferricyanide 

10 '' potassium hydroxide 
100 cc. water 

6. Sodium Picrate — Cementite or Iron Carbide 

2 grams picric acid 

25 grams sodium hydroxide water to make 100 cc. 
Cementite blackened. 



B. FOR THE MACROSTRUCTURE 

LeChatelier and Lemoine Reagent — to develop dendritic 
segregation 
10 grams copper chloride 

40 " magnesium chloride (Increased contrast is de- 
20 cc. hydrochloric acid veloped by washing off 
1800 " water the copper deposit with 

1000 " alcohol ammonia.) 

The author is particularly indebted to Dr. Albert Sauveur, 
Professor of Metallurgy and Metallography in Harvard Uni- 
versity, for his valuable suggestions and for his kindly criticism 
of the proof. 

He wishes to express his warmest thanks to Dr. C. H. Chou for 
the use of Figs. 4, 5, 32, 33 and 38; to the Ludlum Steel Com- 
pany for the use of information of nitrided steel, for the speci- 
mens of nitrided steel and for the specimen of Seminole steel; to 



Vlll PREFACE 

the International Nickel Company for the specimens of cast irons 
containing special elements, and to Barbour and Stockwell Com- 
pany for the semi-steel specimen. Figs. 139, 140, 141 and 142 
were reproduced from Sauveur's Metallography and Heat Treat- 
ment of Iron and Steel, by permission. 

E. L. REED 

Cambridge, Massachusetts, 
June, 1928 



CONTENTS 



PAGE 



Temperature Conversion Table Inside front cover 

Foreword by Dr. Albert Sauveur iii 

Preface v 

PHOTOMICROGRAPHS* 
mONS 

Pure Iron 

FIG. 

1. Electrolytic iron melted in vacuum — 100 X 3 

2. Electrolytic iron melted in vacuum and annealed — 

100 X 3 

3. Same as Fig. 2 — 500 X 3 

4. Electrolytic iron drastically quenched showing Wid- 

manstatten or Martensitic structure — 100 X 4 

5. Same as Fig. 4 — 500 X 4 

Commercial Iron 

6. Iron oxide in iron — 500 X 7 

7. Iron sulphide in iron — 500 X 7 

8. Iron sulphide in iron — 500 X 8 

9. Sulphur print of high sulphur iron ingot (actual size) . . 8 

10. Iron nitride needles in ferrite — 500 X 9 

11. Iron nitride needles in ferrite — 500 X 9 

12. Iron silicate in iron — 500 X '. 9 

13. Sand grain in iron — 500 X 9 

14. Aluminum oxide in iron — 500 X 10 

15. Manganese sulphide in iron — 500 X 10 

16. Commercially pure iron after cold working — 500 X . . 10 

17. Commercially pure iron after quenching in water 

from a high temperature — 500 X 10 

* The magnifications indicated in this table are the original ones. The actual 
magnifications used for reproduction are stated under each photomicrograph. 

ix. 



X CONTENTS 

^I«- PAGE 

18. Neumann bands in ferrite — 100 X 11 

19. Neumann bands in ferrite — 500 X 11 

Wrought Iron 

20. Longitudinal section of muck bar — 100 X 15 

21. Same as Fig. 20 — 500 X . 15 

22. Longitudinal section of wrought iron — 100 X 15 

23. Transverse section of wrought iron — 100 X 16 

24. Pearlite in longitudinal section of wrought iron 

100 X 16 

STEELS 

Impurities in Steel 

25. Manganese sulphide in low carbon cast steel — 500 X 19 

26. Inclusions in low carbon cast steel — 500 X 19 

27. Inclusions in low carbon cast steel — 500 X 20 

28. Manganese sulphide in screw stock — 500 X 20 

29. Titanium nitride or cyanitride in titanium treated 

tool steel — 500 X 20 

Cast Steel and Annealed* Cast Steel 

30. Pipe in ingot — actual size 23 

31. Dendrite — actual size 23 

32. Macrostructure of a 0.52% carbon commercial cast 

steel ingot — 2.5 X 24 

33. Microstructure of same as Fig. 32 — 100 X 24 

34. Macrostructure of same as Fig. 32, after drastic 

annealing — 2.5 X 25 

35. Microstructure of same as Fig. 34 — 100 X 25 

36. 0.50% carbon cast steel, network structure — 100 X . . 26 

37. 0.50% carbon cast steel, network and Widmanstatten 

structure — 100 X 27 

38. 0.50% carbon cast steel, Widmanstatten structure 

-lOOX 28 

39. 0.50% carbon cast steel, network structure — 100 X . . 29 

furna'"''^"^^''^' heating steel above its thermal critical range and cooling in the 



CONTENTS XI 

FIG. PAGE 

40. Same as in Fig. 39 — annealed — 100 X 30 

41. 0.35% carbon commercial cast steel — 100 X 30 

42. Same as Fig. 41 — annealed 30 

43. 0.85% carbon cast steel — 500 X 31 

44. 0.85% " " " — 500 X 31 

45. 1.10% " " " — 100 X 31 

46.1.25%) " " " — 500X 32 

47.1.25% " " " — 500X 33 

48. 1.40% " " " — 100 X 34 

49. Same as in Fig. 48, annealed 100 X 34 

50. 1.40% carbon cast steel etched in 5% nital — 100 X . . 34 

51. Same as in Fig. 50, etched in sodium picrate — 100 X 34 

Hot-rolled Steel 

52. 0.30% carbon steel finishing temperature near critical 

range — 100 X 37 

53-56. Illustrating the relation of microstructure to differ- 
ent finishing temperatures in hot-rolled 0.50% 
carbon steel 37, 38 

57. 0.85% carbon, hot-rolled steel — 500 X 39 

58. 1.25% carbon, hot-rolled steel — 500 X 39 

59. Banded structure in 0.50% carbon steel — 100 X . . . . 39 

60. Banded structure in 0.50% carbon steel — 100 X . . . . 40 

61. Persistent banded structure in 0.85% carbon steel — 

100 X 40 

Cold-rolled Steel and Annealed Cold-rolled Steel 

62. Cold-rolled 0.30% carbon steel — 500 X 43 

63. Cold-rolled 0.30% carbon steel annealed at 550° C. — 

500 X 43 

64. Cold-rolled 0.30% carbon steel annealed at 875° C. — 

500 X 44 

Annealed Hot-rolled Steel 

65. Annealed 0.08% carbon steel — 100 X 47 

66. Same as in Fig. 65 — 500 X 47 

67. Annealed 0.10% carbon steel — 100 X 47 



xii CONTENTS 



FIG. 



PAGE 



68. Annealed 0.20% carbon steel — 100 X 48 

69. " 0.30% " " — lOOx 48 

70. " 0.50%) " " — lOOx 48 

71. " 0.50% '' " — 500X 49 

72. " 0.50% " " — 500X 50 

73. " 0.85% " " — lOOx 51 

74. Same as in Fig. 73, etched in 5% nital — 1000 x . . . . 52 

75. Same as in Fig. 74, etched in sodium picrate — 1000 X 53 

76. Same as in Fig. 74, etched in LeChatelier's reagent 

— lOOOx 54 

77. Annealed 1.10% carbon steel — 500 X 55 

78. Annealed 1.25% carbon steel — 100 X 55 

79. Same as in Fig. 78 — 500 X 55 

Normalized* Hot-rolled Steel 

80. Normahzed 0.50% carbon steel — 500 X 59 

81. Normahzed 0.85% carbon steel — 500 X 60 

82. Normahzed 0.85% carbon steel — 500 X 60 

83. Normahzed 1.25% carbon steel — 500 X 60 

Hardened t Hot-rolled Steel 

84. 0.08% carbon steel quenched from a high tempera- 

ture — 500 X 63 

85. 0.15% carbon steel quenched in water from 926° C. — 

500 X 63 

86. 0.30% carbon steel quenched in water from 883° C. — 

500 X 63 

87. 0.30% carbon steel quenched from a high tempera- 

ture — 500 X 64 

88. 0.50% carbon steel quenched in water from 840° C. — 

500 X 64 

89. 0.85% carbon steel quenched in water from 800° C. — 

500 X 65 

90. 1.25% carbon steel quenched in water from 776° C. — 

500 X 65 

* Normalizing: Heating steel above its thermal critical range and cooling in air. 
t Hardening: Heating steel above its thermal critical range followed by quench- 
ing in a suitable medium, such as oil or water. 



CONTENTS XUl 

FIG. PAGE 

Hardened and Tempered* Hot-rolled Steel 

91. 0.85% quenched carbon steel — tempered at 400° C. 

— 500X 69 

92. 1.25% quenched carbon steel — tempered at 400° C. 

— 500 X 69 

Hardened and Drawn f Hot-rolled Steel 

93. 0.30% quenched carbon steel drawn at 532° C. — 

500 X 73 

94. 0.50% quenched carbon steel drawn at 600° C. — 

500 X 73 

95. 0.85% quenched carbon steel drawn at 600° C. — 

500X 74 

96. 1.25% quenched carbon steel drawn at 600° C. — 

500 X 74 

Study of Transition Constituents According to the Met- 

calf Test 

97-105. Represent a series of photomicrographs showing 
the transition constituents of a bar of 0.50% carbon 
steel heated to a very high temperature at one 
end followed by quenching the entire bar in water 

— 500 X 77-81 

106-112. Represent a series of photomicrographs showing 

the transition constituents of a bar of 0.85% carbon 
steel heated to a very high temperature at one 
end followed by quenching the entire bar in water 

— 500 X 82-88 

113-124. Represent a series of photomicrographs showing 

the transition constituents of a bar of 1.40% carbon 
steel heated to a very high temperature at one 
end followed by quenching the entire bar in water 

— 500 X 89-92 

* Tempering: Reheating hardened steel to temperatures below the critical range 
extending from room temperature to a maximum of 400° C. and cooled either in air 
or in a suitable quenching medium. 

t Dravying: Reheating hardened steel to temperatures above 400° C. — but below 
its critical range — and cooling in air or quenching in a suitable quenching medium. 



XIV CONTENTS 

Spheroidized Steel 

FIG. PAGE 

125. Partially spheroidized steel — 1000 X 95 

126. Fully spheroidized steel — 1000 X 96 

Graphitized Cementite 

127. Graphitized cementite — 500 X 99 

128. Graphitized cementite — 500 X 100 

Overheated and Burnt Steel 

129. Overheated 0.50% carbon steel — 100 X 103 

130. Bmiit 1.25% carbon steel — 500 X 104 

Grain Growth in Mild Steel 

131. Grain growth in 0.08% carbon steel — Brinnell Ball 

Test — 5.5X 107 

132. Grain growth in 0.08% carbon steel — 100 X 108 

133. Grain growth in 0.08% carbon steel — 100 X 109 

Case-hardened Carbon Steel and Heat treated Case- 
hardened Carbon Steel 

134. Case-hardened 0.15% carbon steel cooled slowly after 

carburizing — 0.85% carbon case — 100 X 113 

135. Same as in Fig. 134 after recommended heat treat- 

ment — 100 X 113 

136. Case-hardened 0.15% carbon steel, cooled slowly after 

carburizing — 1-40% carbon case — 100 X 114 

137. Same as in Fig. 136 after recommended heat treat- 

ment — 100 X 114 

138. Phosphorus segregation in case-hardened steel — 

100 X 115 

139. Case of normal steel — 50x 116 

140. Case of abnormal steel — 50 X 116 

141. Hyper-eutectoid zone of normal case — 200 X 116 

142. Hyper-eutectoid zone of abnormal case — 200 X 116 

Decarburized Steel 

143. Decarburized 1.40% carbon steel — 100 X 119 



CONTENTS XV 

ALLOY STEEL 

A. Nickel Steel — Cast, Forged, Annealed and after Recom- 
mended Heat Treatment 

FIG. PAGE 

144. Cast nickel steel, 0.30%carbon, 3^%nickel— lOOX . . . 123 

145. Hot-rolled nickel steel, 0.30% carbon, 3|% nickel — 

lOOx 123 

146. Annealed nickel steel, 0.35% carbon, 3|% nickel — 

lOOX 123 

147. Heat treated nickel steel, 0.30% carbon, 3|% nickel 

— 100 X 124 

148. Hot-rolled nickel steel, 0.30% carbon, 5% nickel — 

lOOX 124 

B. Chromium Steel — Annealed and after Recommended 
Heat Treatment 

149. Annealed chromium steel, 0.40% carbon, 0.95% 

chromium — 500 X 127 

150. Same as in Fig. 149, heat treated — 500 X 127 

151. Annealed chromium steel, 1.00% carbon, 1.35% 

chromium — 500 X 127 

152. Same as in Fig. 151, heat treated — 500x 128 

153. Annealed stainless steel, 0.30% carbon, 12% chrom- 

ium — 500 X 128 

154. Same as in Fig. 153, heat treated — 500 X 128 

C. Nickel-chromium Steel — Annealed and after Recom- 
mended Heat Treatment 

155. Annealed nickel-chromium steel, 0.30% carbon, 1.75% 

nickel, 1.00% chromium — 500 X 131 

156. Same as in Fig. 155, heat treated — 500 X 131 

157. Annealed nickel-chromium steel, 0.35% carbon, nickel 

3.50% chromium 1.50% — 500 X 131 

158. Same as in Fig. 157, heat treated — 500 X 131 

D. Chrome-vanadium Steel — Annealed after Recom- 
mended Heat Treatment 

159. Annealed chrome-vanadium steel, 0.35% carbon, 

0.95% chromium, 0.18% vanadium — 500 X 135 



xvi CONTENTS 

FIG. PAGE 

160. Same as in Fig. 159, heat treated — 500 X 135 

161. Annealed chrome- vanadium steel, 1.00% carbon, 

0.90% chromium, 0.18% vanadium — 500 X 135 

162. Same as in Fig. 161, heat treated — 500 X 135 

E. Molybdenum Steel — Annealed and after Recom- 
mended Heat Treatment 

163. Annealed molybdenum steel, 0.40% carbon, 0.95% 

chromium, 0.20% molybdenum — 500 X 139 

164. Same as in Fig. 163, heat treated — 500 X 139 

F. Hadfield Manganese Steel — Cast and after Recom- 
mended Heat Treatment 

165. Cast manganese steel, 1.00% carbon, 12% man- 

ganese — 100 X 143 

166. Same as in Fig. 165 — 500 X 143 

167. Same as in Figs. 165 or 166, after heat treatment — 

500X 143 

G. Silicon Steel — as Cast 

168. Cast silicon steel, 0.15% carbon, 4.50% silicon — 

100 X 147 

H. Silico-manganese Steel — Annealed and after Recom- 
mended Heat Treatment 

169. Annealed sihco-manganese steel, 0.50% carbon, 0.75% 

manganese, 2.00% siHcon — 500 X 151 

170. Same as in Fig. 169, heat treated — 500 X 151 

I. Chrome-tungsten Steel (High-speed) — Cast, Annealed 
and after Recommended Heat Treatment 

171. Cast high-speed steel, 0.60% carbon, 17% tungsten, 

and 3.50% chromium etched in 5% nital — 500 X . . 155 

172. Same as in Fig. 171, etched in Murakami's reagent — 

500 X 155 

173 and 174. Other examples of cast high-speed steel 

etched in Murakami's reagent — 500 X 155 



CONTENTS XVll 

FIG. PAGE 

175. Annealed high-speed steel, 0.60% carbon, 17% tung- 

sten, 3.50% chromium — 500 X 156 

176. Same as in Fig. 175, heat treated — 1000 X 156 

177. Same as in Fig. 175, heat treated — 1000 X 156 

J. Special Alloy Steel — Possessing Properties of Hardness 
and Toughness — after Recommended Heat Treatment 

178. Seminole steel, alloy steel containing tungsten and 

chromium annealed, — 500 X 159 

179. Seminole steel, alloy steel containing tungsten and 

chromium, hardened — 500 X 160 

180. Seminole steel, alloy steel containing tungsten and 

chromium, hardened and tempered — 500 X 160 

K. Non-scaling Steel 

181. Hadfield Era A. T. V. Alloy steel containing silicon, 

chromium, nickel and tungsten — 500 X 163 

Case-hardened Alloy Steels — after Recommended Heat 

Treatment 

(1) Nickel Steel 

182. Case-hardened nickel steel, 0.20% carbon and 5.00% 

nickel, heat treated — 100 X 167 

(2) Chromium Steel 

183. Case-hardened chromium steel, 0.20% carbon, and 

0.75% chromium, heat treated — 100 X 167 

(3) Nickel-chromium Steel 

184. Case-hardened nickel-chromium steel, 0.17% carbon, 

3.50% nickel, 1.50% chromium, heat treated — 

100 X 168 

(4) Molybdenum Steel 

185. Case-hardened molybdenum steel, 0.15% carbon, 

1.50% nickel, 0.25% molybdenum, heat treated — 
lOOx 168 



XVlll CONTENTS 

(5) Chrome-vanadium Steel 

FIG. PAGE 

186. Case-hardened chrome-vanadium steel, 0.20% car- 

bon, 0.95% chromium, 0.18% vanadium, heat 
treated — 100 X 169 

Annealed Nitralloy (steel used for nitriding; and 
Nitrided Steels 

187. Annealed nitralloy — 500 X carbon 0.36%, manganese 

0.51%, silicon 0.27%, aluminum 1.23Sr, chromium 
1.49%, sulphur 0.010%,, phosphorus 0.013%, mo- 
lybdenum 0.18%— lOOx '. 173 

188. Nitrided nitralloy 173 

189-193. Microstructures of the nitrided case as shown in 

Fig. 183 — 500 X 174, 175 

CAST IRONS 
Gray Iron 

194. Gray cast iron, no combined carbon — 500 X 179 

195. Gray cast iron, no combined carbon, with steadite — 

500X 179 

196. Gray cast iron, containing about 0.40% combined 

carbon, with steadite — 500 X 179 

197. Gray cast iron, containing about 0.60% combined 

carbon — 500 X . 179 

198. Gray cast iron, containing about 0.60% combined 

carbon, with steadite — 500 X ISO 

199. Gray cast iron, containing 0.85%, combined carbon 

— 500 X 180 

200. Gray cast iron, containing 0.85%, combined carbon 

with steadite — 500 X 180 

201. Gray cast iron, containing 1.25% combined carbon 

— 500 X 180 

Mottled Cast Iron 

202. Cast iron, partially white and partially gray iron — 

500 X 183 



CONTENTS XIX 

White Cast Iron 

FIG. PAGE 

203. White cast iron — 500 X 187 

204. White cast iron — 500 X 188 

Malleablized Cast Iron 

205. Partially malleablized cast iron — 500 X 191 

206. Fully malleablized cast iron — 500 X 192 

Manganese Sulphide in Cast Iron 

207. Manganese sulphide in partially malleablized cast 

iron — 500 X 195 

Phosphide Eutectic in Cast Iron 

208. Phosphorus eutectic in cast iron, etched in 5% nital 

— 500X 199 

209. Same as in Fig. 203, after etching in sodium picrate — 

500 X 199 

210. Same as in Fig. 204, after heat-tinting — 500 X 200 

Chilled Cast Iron 

211-213. Represent a series of microstructures of sections 

through a chilled cast iron specimen 203 

SEMI-STEEL 

214. Cast iron with eutectoid matrix, shown in Fig. 214 — 

100 X 207 

215. Semi-steel with eutectoid matrix — 100 X 207 

CAST IRON CONTAINING SPECIAL ELEMENTS 

216. Gray cast iron, total carbon 3.16%, silicon 2.63% — 

100 X 211 

217. Gray cast iron, total carbon 3.17%, sihcon 1.14%, 

nickel 2.83% — 100 X 211 

218. Gray cast iron, total carbon 3.11%, sihcon 2.20%, 

nickel 1.11%, chromium 0.38% — 100 X 212 



XX CONTENTS 

APPENDIX 

PAGE 

A. The Preparation of Metallographic Specimens 215 

B. Etching Solutions for Microscopic Examinations 

OF Steels and Irons 219 

C. Microscopes 229 

D. Photomicrography 232 

E. Definitions 244 

(a) Standard definitions of terms relating to Metal- 

lography 244 

(b) Definitions of other Metallographic terms 246 

(c) Tentative definitions of terms relating to Heat 

treatment operations 251 



PURE IRON 
Figs. 1-5 inclusive 



PHOTOMICROGRAPHS OF IRON AND STEEL 



PURE IRON 





Fig. 1 



Fig. 2 




Fig. 3 



Fig. 1. Electrolytic iron melted in vacuum. Large grains of ferrite. Etched in 
5%Nital. 50 X. Original magnification, 100 X. 

Fig. 2. Electrolytic iron melted in vacuum and subsequently heated to 1000° C. 
for 15 minutes and cooled in furnace. Polyhedral grains of ferrite. Etched in 5% 
Nital. 50 X. Original magnification, 100 X. 

Fig. 3. Same as in Fig. 2, more highly magnified. 250 X. Original magnifica- 
tion, 500 X. 



PHOTOMICROGRAPHS OF IRON AND STEEL 



PURE IRON 




Fig. 4 




Fig. 5 



Fig. 4. Electrolytic iron drastically quenched. Original austenitic grain bounda- 
ries and martensitic structure. 50 X. Original magnification. 100 X. 

Fig. 5. Same as in Fig. 4, more highly magnified. 250 X. Original magnification, 
500 X. 



COMMERCIAL IRON 
Figs. 6-19 inclusive 



PHOTOMICROGRAPHS OF IRON AND STEEL 



COMMERCIAL IRON 




Fig. 6 




Fig. 7 



Fig. 6. Iron oxide in commercially pure iron. Etched in 5% Nital. 250 X. 
Original magnification, ,500 X . 

Fig. 7. Iron sulphide forming continuous membrane around ferrite grains. Sul- 
phur content, 0.62%. Etched in 5% Nital. 375 X. Original magnification, 500 X. 



8 



PHOTOMICROGRAPHS OF IRON AND STEEL 



COMMERCIAL IRON 



w 



\,i> 

"i',^^ 

w-^^ 






>^-/ 



^^"S". .Jy' 



k^r y " 
w. .-\\. 



Fig. 8 




Fig. 9 



Fig. 8. Another example of iron sulphide in ferrite. Sulphur content, 0.62%. 
Etched in 5% Nital. 250X. Original magnification, 500 X. 

Fig. 9. Sulphur print of high sulphur-iron ingot. Sulphur content, 0.62%. 
Actual size. 



PHOTOMICROGRAPHS OF IRON AND STEEL 



COMMERCIAL IRON 



.a> 


-^^^ " 


^: '9 


^V, 


:UX~'. 




i.. '^ -^ 


v> 




Fig. 10 



Fig. 11 




? . 


i{^ 










1 /■■' 
' I,' ' 




^" 


;« 




«» • 


^ 


i. 





Fig. 12 



Fig. 13 



Fig. 10. Iron nitride needles in ferrite. Etched in 5% Nital. 250X. Original 
magnification, 500 X. 

Fig. U. Iron nitride needles in ferrite. Etched in 5% Nital. 250X. Original 
magnification, 500 X. 

Fig. 12. Iron silicate in iron. Unetched. 250 X. Original magnification, 500 X. 

Fig. 13. Sand grain in iron. Unetched. 250 X. Original magnification, 500 X. 



10 



PHOTOMICROGRAPHS OF IRON AND STEEL 



COMMERCIAL IRON 



ty • 














1^ 



! 
1 
/ 

/ 


/ 


* . 


- 












% 



Fig. 14 



Fig. 15 



^^^gg^i^'\ xiy^A -^ : 


;<- 1 ;J.Siira.f<MjJ^,vSi»-;^:;. . '. 


<.-^^^^^ ,' - 


.'J' 


- r 


f""' . ■'^-'' 




V ^' 


• ' 


^ 




,. . ^ .--'■ 




" -X:..l:^- 


. * 




r-^ _.,--'/ 






■ '■" : ^ -^ 


VT- 




_ 


'• ' ^■* ' 


■^ 


.'. y \ 




Fig. 16 



Fig. 17 



Fig. 14. Grains of alumina (AI2O3), in ferrite. Unetched. 250 X. Original 
magnification, 500 X. 

Fig. 15. Manganese sulphide in ferrite. Etched in 5 ^^ Nit al. 250 X. Original 
magnification, 500 X. 

Fig. 16. Armco iron. Cold worked. Deformed ferrite grains. Etched in 5*^ 
Nital. 250 X. Original magnification, 500 X . 

Fig. 17. Armco iron heated nearly to melting point and quenched in cold water. 
Etched in 5% Nital. 250X. Original magnification, 500 X. 



PHOTOMICROGRAPHS OF IRON AND STEEL 
COMMERCIAL IRON 



11 



■ .\ ""W 




— — - 


i 






-:- 


■ »i 


\ ' 


^^^ - 




A 


\ " - 


•7^ -v.: 

* / 


A\ 


\ 


y'if.^\ s X 




■'\ 


V ^ 


'^''-. w 






■-- \ 


4 
/ S 


! 


f 


1 



Fig. 18 




Fig. 19 

Fig. 18. Neumann bands in ferrite. Etched in 5% Nital. 75 X. Original 
magnification, 100 X. 

Fig. 19. Neumann bands in ferrite. Etched in 5% Nital. 375 X. Original 
magnification, 500 X. 



WROUGHT IRON 
Figs. 20-24 inclusive 



13 



PHOTOMICROGRAPHS OF IRON AND STEEL 



15 



WROUGHT IRON 





Fig. 20 



Fig. 21 




Fig. 22 



Fig. 20. Muck bar. Longitudinal section. Etched in5% Nital. 50 X. Origi- 
nal magnification, 100 X . 

Fig. 21. Muck bar. Longitudinal section, showing duplex structure of slag. 
Etched in 5% Nital. 250 X. Original magnification, 500 X. 

Fig. 22. Wrought iron. Longitudinal section. Etched in 5% Nital. 50 X. 
Original magnification, 100 X . 



16 



PHOTOMICROGRAPHS OF IRON AND STEEL 



WROUGHT IRON 



:- , • - •^■-;;^- - !-:-7^' 




r*/''-'''^;' -■■.^■•': 


■ .: -'" 


,:/ .'/^*;;: .,;...;• 


■ ;>-' 


. ■ ,.' . ^ '.•>■ 


■■-■»■ 


. ' *'-' ;v- '\'f ■:-■-' ■ 




••' , ^ ' ■'■»■■'.• 


\ 




■'■■' ".^ 


. . ' . 





Fig. 23 



■^■^- -^.^^M/^- 







_.. . •^ J^^,.v^^^-'^ .AV-- - -^ 



Fig. 24 



Fig. 23. Wrought iron. Transverse section. Etchedin5%NitaI. 50 X. Origi- 
nal magnification, 100 X . 

Fig. 24. Wrought iron. Longitudinal section. Black fibers of slag running in 
the direction of rolling. Small black pearlite grains situated at the boundaries of 
the white ferrite grains. Etched in 5% Nital. 50 X. Original magnification, 
lOOX. 



IMPURITIES IN STEEL 
Figs. 25-29 inclusive 



17 



PHOTOMICROGRAPHS OF IRON AND STEEL 



19 



IMPURITIES IN STEEL 




Fig. 25 




Fig. 26 



Fig. 25. Manganese sulphide in low carbon cast steel. Etched in 5% Nital. 
250 X . Original magnification, 500 X . 

Fig. 26. An inclusion in low carbon cast steel. Etched in 5% Nital. 250 X. 
Original magnification, 500 X. 



20 



PHOTOMICROGRAPHS OF IRON AND STEEL 



IMPURITIES IN STEEL 





Fig. 27 



Fig. 28 




Fig. 29 



Fig. 27. Inclusions in low carbon cast steel. Etched in 5% Nital. 250 X. 
Original magnification, 500 X. 

Fig. 28. Elongated particles of manganese sulphide in screw stock material. 
Carbon, 0.20%; manganese, 0.70%; sulphur, 0.11%. Etched in 5% Nital. 250X. 
Original magnification, 500 X. 

Fig. 29. Cubic crystal of titanium nitride or cyanitride in titanium treated tool 
steel. The cubic crystal is pink in color. 250 X. Original magnification, 500 X. 
Unetched. 



CAST STEEL 

AND 

ANNEALED CAST STEEL 

Figs. 30-51 inclusive 



21 



PHOTOMICROGRAPHS OF IRON AND STEEL 
CAST STEEL 



23 




Fig. 31 
Fig. 30. Photograph of a cast steel ingot cut longitudinally showing the pipe in 

the upper part of the ingot. One-half natural size. 

Fig. 31. Photograph of a crystallite, sometimes called a dendrite, a fir tree crystal, 

or a pine tree crystal. These dendrites are found in pipes in castings. Actual size. 



24 



PHOTOMICROGRAPHS OF IRON AND STEEL 
CAST STEEL 




Fig. 32 




Fig. 33 

Fig. 32. Macrostructure of a steel ingot containing 0.52% carbon and 0.097% 
phosphorus. Dendritic segregation. Etched in LeChateHer's reagent. 1.7 X. 
Original magnification, 2.5 X. 

Fig. 33. Microstructure of ingot shown in Fig. 32. Etched in 5% Nital. 
Original magnification, 66.7 X. 



PHOTOMICROGRAPHS OF IRON AND STEEL 
CAST STEEL 



25 




Fig. 34 



i^:i<^^^<^ 



^. 



c 

* 



"if' 







Fig. 35 

Fig. 34. Macrostructure of ingot shown in Fig. 32, after annealing one hour at 
1000° C. Persistence of dendritic segregation. Etched in LeChateher's reagent. 
1.7 X. Original magnification, 2.5 X. 

Fig. 35. Microstructure of ingot shown in Fig. 34. Etchedin 5% Nital. 66.7X. 
Original magnification, 100 X. 



26 



PHOTOMICROGRAPHS OF IRON AND STEEL 



CAST STEEL 




Fig. 36 



Fig. 36. Steel. Cast. 0.50% carbon. Large sorbito-pearlite grains surrounded 
by a ferrite membrane from which occasionally radiates ferrite. Etched in 5% Nital. 
50 X. Original magnification, 100 X. 



PHOTOMICROGRAPHS OF IRON AND STEEL 



27 



CAST STEEL 




Fig. 37 



Fig. 37. Steel. Cast. 0.50% carbon. Large sorbite or sorbito-pearlite grains 
surrounded by a ferrite boundary from which ferrite radiates, also some ferrite is 
precipitated along the octahedral crystallographic planes. Etched in 5% Nital. 
50 X. Original magnification, 100 X. 



28 



PHOTOMICROGRAPHS OF IRON AND STEEL 




Fig. 38. Steel. Cast. 0.50% carbon. Slowly cooled through the critical range. 
The ferrite is retained in the crystallographic planes. The structure is known as 
Widmanstatten or cleavage structure. Etched in 5% Nital. 50 X. Original mag- 
nification, 100 X. 



PHOTOMICROGRAPHS OF IRON AND STEEL 



29 



CAST STEEL 




Fig. 39 



Fig. 39. Steel. Cast. 0.50% carbon. Network structure. Etched in 5% 
Nital. 50 X. Original magnification, 100 X. 



30 



PHOTOMICROGRAPHS OF IRON AND STEEL 



CAST STEEL 




Fig. 40 



Fig. 41 




Fig. 42 



Fig. 40. Same steel as shown in Fig. 39 after annealing 5 hours at 850° C. 
Grain refinement. Etched in 5% Nital. 50 X. Original magnification, 100 X . 

Fig. 41. Steel. Cast. 0.40% carbon. Etched in 5% Nital. 50X. Original 
magnification, 100 X. 

Fig. 42. Same steel as shown in Fig. 41, after annealing 5 hours at 850° C. 
Etched in 5% Nital. 50 X. Original magnification, 100 X. 



PHOTOMICROGRAPHS OF IRON AND STEEL 



31 



CAST STEEL 





Fig. 43 



Fig. 44 






Fig. 45 



Fig. 43. Steel. Cast. 0.85% carbon. Lamellar pearlite. Etcheclin5% Nital. 
250 X. Original magnification, 500 X. 

Fig. 44. Another spot on same specimen, the structure of which is shown in 
Fig. 43. 250 X. Original magnification, 500 X. 

Fig. 45. Steel. Cast. L 10% carbon. Large grains of pearlite surrounded by a 
fine membrane of cementite. Etched in 5% Nital. 50 X. Original magnification, 
100 X. 



32 



PHOTOMICROGRAPHS OF IRON AND STEEL 



CAST STEEL 







^ r 7 'a 




Fig. 46 

Fig. 46. Steel. Cast. 1.25% carbon. Cementite partially rejected along cleav- 
age planes and around grain boundaries. Etched in 5% Nital. 375 X. Original 
magnification, 500 X. 



PHOTOMICROGRAPHS OF IRON AND STEEL 



33 



CAST STEEL 




Fig. 47 



Fig. 47. Steel. Cast. 1.25% carbon. Cementite persisting around boundaries 
of pearlite grains. Etched in 5% Nital. 375 X. Original magnification, 500 X. 



34 



PHOTOMICROGRAPHS OF IRON AND STEEL 



CAST STEEL 





Fig. 48 



Fig. 49 





Fig. 50 



Fig. 51 



Fig. 48. Steel. Cast. 1.40% carbon. Cementite between cleavage plane.s. 
Etched in 5% Nital. 50 X. Original magnification, 100 X. 

Fig. 49. Same steel shown in Fig. 48 after annealing 5 hours at 850° C. Cement- 
ite rejected to boundaries of pearlitc grains. Etched in 5% Nital. 50 X. Original 
magnification, lOOX. 

Fig. 50. Steel. Cast. 1.40% carbon. Cementite rejected to the boundaries 
and separated along cleavage planes. Etched in 5% Nital. 50 X. Original mag- 
nification, 100 X. 

Fig. 51. Same spot as shown in Fig. 50 after repolishing and etching in boiling 
sodium picrate. The cementite is blackened. 



HOT-ROLLED STEEL 
Figs. 52-61 inclusive 



35 



PHOTOMICROGRAPHS OF IRON AND STEEL 



37 



HOT-ROLLED STEEL 





Fig. 52 



Fig. 53 




Fig. 54 



Fig. 52. Steel. Hot-rolled. 0.30% carbon. Correct finishing temperature, 
namely, just above critical range. Etched in 5% Nital. 100 X. 

Fig. 53. Steel. Hot-rolled. 0.50% carbon. Finishing temperature consider- 
ably above the critical range. Etched in 5% Nital. 50 X. Original magnification, 
100 X. 

Fig. 54. Steel. Hot-rolled. 0.50% carbon. Finishing temperature consider- 
ably above the critical range. Etched in 5% Nital. 50 X. Original magnification, 
lOOX. 



38 



PHOTOMICROGRAPHS OF IRON AND STEEL 



HOT-ROLLED STEEL 




Fig. 




Fig. 56 



Fig. 55. Steel. 

the critical range. 

Fig. 56. Steel. 



Hot-rolled. 0.50% carbon. 
Etched in 5% Nital. 50 X. 
Hot-rolled. 0.50% carbon. 



Finishing temperature just above 
Original magnification, 100 X. 
Finishing temperature near the 



critical range. Etched in 5% Nital. 50 X. Original magnification, 100 X. 



PHOTOMICROGRAPHS OF IRON AND STEEL 



39 



HOT-ROLLED STEEL 




Fig. 57 



Fig. 58 




Fig. 59 



Fig. 57. Steel. Hot-rolled. 0.85% carbon. Sorbito-pearlite. Etched in 5% 
Nital. 500 X. 

Fig. 58. Steel. Hot-rolled. 1.25% carbon. Sorbito-pearlite and traces of 
cementite boundaries around grains. Finishing temperature near the critical range. 
Etched in 5% Nital. 500 X . 

Fig. 59. Steel. Hot-rolled. 0.50% carbon. Banded structure. The light-col- 
ored bands are rich in phosphorus and also contain many inclusions. Etched in 
5% Nital. 50 X. Original magnification, 100 X. 



40 



PHOTOMICROGRAPHS OF IRON AND STEEL 



HOT-ROLLED STEEL 




Fig. 60 



ift|MM|||8gB|A^gK 






yir ^5^/ '''^5*7 ■ ^Pl^ 


'tj^'z:r-- . :^-'^x 








liX-MT.rJ^ '^ 




•^^ 


'■■:tP''^%/'^JM .?^:] 


- • .3 
.. . ■* 


'#«K-^y-^' :;• 


f 


l^ilflliM^^*^^— ' 


m 


^gfWHgHB^j^ 




w 


i^^^Kt^m Ayi. V - <5-i ^'.^ .z^^^^H 


^ 




sr 


i*V-^- 




... .^— y. 

\ - .. ' . ■ 


■Vj 


^- 



Fig. 61 



Fig. 60. Steel. Hot-rolled. 0.50% carbon. Banded structure. The white 
band.s are rich in phosphorus and are not etched by the reagent. Etched in 
LeChateher's reagent. 50 X . Original magnification, 100 X . 

Fig. 61. Steel. Hot-rolled. 0.85% carbon. Banded structure caused by per- 
.sistent dendritic segregation. The white bands contain impurities. Etched in 
LeChateher's reagent. 50 X. Original magnification, 100 X. 



COLD-ROLLED STEEL 
AND 
ANNEALED COLD-ROLLED STEEL 

Figs. 62-64 inclusive 



41 



PHOTOMICROGRAPHS OF IRON AND STEEL 



43 



COLD-ROLLED STEEL AND ANNEALED COLD-ROLLED STEEL 







Fig. 62 




Fig. 63 



Fig. 62. Steel. Cold-rolled. 0.30% carbon. Deformed ferrite and pearlite 
grains. Etched in 5% Nital. 375 X. Original magnification, 500 X. 

Fig. 63. Steel. Cold-rolled. 0.30% carbon. Annealed at 550° C. Equiaxed 
ferrite grains and deformed pearlite. Etched in 5% Nital. 375 X. Original mag- 
nification, 500 X. 



44 



PHOTOMICROGRAPHS OF IRON AND STEEL 



COLD-ROLLED STEEL AND ANNEALED COLD-ROLLED STEEL 



^■*^^nM rite 







Fig. 64 



Fig. 64. Steel. Cold-rolled. 0.30% carbon. Annealed at 850° C. Equiaxed 
ferrite and pearlite grains. Etched in 5% Nital. 375 X. Original magnification, 
500 X. 



ANNEALED HOT-ROLLED STEEL 
Figs. 65-79 inclusive 



45 



PHOTOMICROGRAPHS OF IRON AND STEEL 



47 



ANNEALED HOT-ROLLED STEEL 



s 


C^^-^-^l-^^-^'T"'- 


'"" -v 


^': 




■ V 


-'■ 


-; . ' y 






- ' ■ ^ •- V - J ■ . 


.' 




" . - i ^ i ' 




A ■' 






t 






>. . 


■■■.;- --v 




~-t- 


■--'i-^ / .' -\ -' — 


- -. -x. 




Fig. 65 



Fig. 66 






^ .-V 



-. \ 



•t 






■i •/ ) 









••^^^ 






Fig. 67 



Fig. 65. Steel. Annealed. 0.08% carbon. Polyhedral grains of ferrite and 
small black islands of pearlite. Etched in 5% Nital. 100 X. 

Fig. 66. Steel. Annealed. 0.08% carbon. Pearlite grains resolved under high 
magnification. Etched in 5% Nital. 250 X. Original magnification, 500 X . 

Fig. 67. Steel. Annealed. 0.10% carbon. Polyhedral grains of ferrite and 
dark grains of pearlite. Etched in 5% Nital. 100 X. 



48 



PHOTOMICROGRAPHS OF IRON AND STEEL 



ANNEALED HOT-ROLLED STEEL 










Fig. 68 



Fig. 69 




i 



Fig. 70 

Fig. 68. Steel. Annealed. 0.20% carbon. Ferrite and pearlite grains. Etched 
in5%Nital. 100 X. 

Fig. 69. Steel. Annealed. 0.30% carbon. Ferrite and pearlite grains. Etched 
in5%Nital. 100 X. 

Fig. 70. Steel. Annealed. 0.50% carbon. Pearlite grains surrounded by a 
membrane of ferrite. Etched in 5% Nital. 100 X. 



PHOTOMICROGRAPHS OF IRON AND STEEL 



49 



ANNEALED HOT-ROLLED STEEL 







Fig. 71 

Fig. 71. Steel. Annealed. 0.50% carbon. Ferrite surrounding grains of sorbito- 
pearlite. Etched in 5% Nital. 375 X. Original magnification, 500 X . 



50 



PHOTOMICROGRAPHS OF IRON AND STEEL 



ANNEALED HOT-ROLLED STEEL 




Fig. 72 



Fig. 72. Same steel as shown in Fig. 71. Ferrite and pearlite. Etched in 5% 
Nital. 375 X. Original magnification, 500 X. ^ 



PHOTOMICROGRAPHS OF IRON AND STEEL 



51 



ANNEALED HOT-ROLLED STEEL 



Hi 




^^^»o 




WM 


^^9Hh| 


H^si^^^ 


'"^^^Mtf^mP 




^^/Bm 


Ba^^^^H 


KIjI^^- 


^^^^|H 




^^BHH 


l^pB 


^^^^s.'' 






^^M 


bI^B 


^m 


<i9B 




^^m 


■^H 








^Km 


pB^Hp 




''w^' 




■^jg^M. 


HE 




4 


f4h^^^ 


^H 


^^^1| 


't^if'^ 


&^^3 


^T 


^^B 


B@)(j^@G^^^^ 






fB^^fit^ 


'^BB^H 


i^BB^^^S^^^i 






1^^^^^. 


..^jj^BI^^^^H 


^B 




"I^ISmI 




H 


S^^p! 




1^^ 




^^^s 



Fig. 73 



Fig. 73. Steel. Annealed. 0.85% carbon. 100% pearlite. Etched in h% 
Nital. 75 X. Original magnification, 100 X. 



52 



PHOTOMICROGRAPHS OF IRON AND STEEL 



ANNEALED HOT-ROLLED STEEL 




Fig. 74 



Fig. 74. Steel. Annealed. 0.85% carbon. Lamellar pearlite. Etched in 5% 
Nital. 750 X. Original magnification, 1000 X. 



PHOTOMICROGRAPHS OF IRON AND STEEL 



53 



ANNEALED HOT-ROLLED STEEL 




Fig. 75 



Fig. 75. Same spot as shown in Fig. 74, after repolishing and etching in boihng 
sodium picrate. The cementite in the pearlite is blackened. 750 X. Original mag- 
nification, 1000 X. 



54 



PHOTOMICROGRAPHS OF IRON AND STEEL 



ANNEALED HOT-ROLLED STEEL 




Fig. 76 



Fig. 76. Same spot as shown in Fig. 75 after repolishing aiul etching in 
LeChatelier's reagent. 750 X. Original magnification, 1000 X. 



PHOTOMICROGRAPHS OF IRON AND STEEL 



55 



ANNEALED HOT-ROLLED STEEL 




'j^^^^-^ 

'{'■■r^-^ 






Fig. 77 



Fig. 78 



;*. 



<" ^ V 







Fig. 79 

Fig. 77. Steel. Annealed. L 10% carbon. Lamellar-pearlite grains surrounded 
by a fine membrane of cement ite. Etched in 5% Nital. 250 X. Original magnifi- 
cation, 500 X. 

Fig. 78. Steel. Annealed. L25% carbon. Pearlite grains surrounded by a 
membrane of cementite. Etched in 5% Nital. 100 X. 

Fig. 79. Same as in Fig. 78. More highly magnified. 250 X. Original mag- 
nification, 500 X. 



NORMALIZED HOT-ROLLED STEEL 
Figs. 80-83 inclusive 



57 



PHOTOMICROGRAPHS OF IRON AND STEEL 



59 



NORMALIZED HOT-ROLLED STEEL 




Fig. 80 



Fig. 80. Steel. Normalized. 0.50% carbon. Grain.s of sorbite .surrounded by 
a membrane of ferrite. Etched in 5% Nital. 375 X . Original magnification, 500 X . 



60 



PHOTOMICROGRAPHS OF IRON AND STEEL 
NORMALIZED HOT-ROLLED STEEL 




Fig. 81 




Fig. 82 



mm 

mm 


^ 




^wffi 


m^ 


WF 



Fig. 83 



Fig. 8L Steel. Normalized. 0.85% carbon. Sorbito-pearlite. Etched in 5% 
Nital. 375 X. Original magnification, 500 X. 

Fig. 82. Steel. Normalized. 0.85% carbon. Sorbite. Etched in 5% Nital. 
500 X. 

Fig. 83. Steel. Normalized. 1.25% carbon. Sorbite and cementite. Etched 
in 5% Nital. 500 X. 



HARDENED HOT-ROLLED STEEL 
Figs. 84-90 inclusive 



61 



PHOTOMICROGRAPHS OF IRON AND STEEL 
HARDENED HOT-ROLLED STEEL 



63 




Fig. 84 




Fig. 85 



;JMMW|\^^^^ffi^^ 


^S 




w 




^^^ 




^p 




^^^^R 


^^^ 


^^ 


^ilp^^a 


^m 




^ 










B^HEs^^^3^^i^^^^ 




:^^^ 


HI 



Fig. 86 



Fig. 84. Steel. 0.08% carbon. Heated to a temperature considerably above 
the critical range and quenched in water. Martensite. Etched in 5% Nital. 
250 X. Original magnification, 500 X. 

Fig. 85. Steel. 0.15% carbon. Heated to 926° C. and quenched in water. 
Etched in 5% Nital. 250 X. Original magnification, 500 X. 

Fig. 86. Steel. 0.30% carbon. Heated to 883° C. and quenched in water. 
Etched in 5% Nital. 250 X. Original magnification, 500 X. 



64 



PHOTOMICROGRAPHS OF IRON AND STEEL 



HARDENED HOT-ROLLED STEEL 




Fig. 87 



rt« 


■ 


^^^^^^ 


^^^^^ 


^^^^ 


^^H 


^^^s 


^^H 


l^^^p^ 


s^^Sm 



Fig. 88 

Fig. 87. Steel. 0.30% carbon. Heated to a temperature considerably above 
the critical temperature and quenched in water. Etched in 5% Nital. 250 X. 
Original magnification, 500 X. 

Fig. 88. Steel. 0.50% carbon. Heated to 840° C. and quenched in water. 
Martensite. Etched in 5% Nital. 500 X. 



I 



PHOTOMICROGRAPHS OF IRON AND STEEL 



65 



HARDENED HOT-ROLLED STEEL 







^m 




^^^^H 






^^H 


^B 




^^^ 



Fig. 89 




Fig. 90 



Fig. 89. Steel. 0.85% carbon. Heated to 800° C. and quenched in water. 
Fine martensite. Etched in 5% Nital. 500 X. 

Fig. 90. Steel. 1.25% carbon. Heated to 776° C. and quenched in water 
Fine martensite. Etched in 5% Nital. 500 X. 



HARDENED AND TEMPERED HOT-ROLLED STEEL 
Figs. 91 and 92 



67 



PHOTOMICROGRAPHS OF IRON AND STEEL 69 

HARDENED AND TEMPERED HOT-ROLLED STEEL 




Fig. 92 

Fig. 91. Steel. 0.85% carbon. Heated to 800° C. and quenched in oil; tem- 
pered at 400° C. and quenched in oil. Troostite. Etched in 5% Nital. 500 X. 

Fig. 92. Steel. 1.25% carbon. Heated to 776° C. and quenched in oil; tem- 
pered at 400° C. and quenched in oil. Troostite. Etched in 5% Nital. 500 X. 



HARDENED AND DRAWN HOT-ROLLED STEEL 
Figs. 93-96 inclusive 



71 



PHOTOMICROGRAPHS OF IRON AND STEEL 



73 



HARDENED AND DRAWN HOT-ROLLED STEEL 




Fig. 93 




Fig. 94 



Fig. 93. Steel. 0.35% carbon. Heated to 912° C. and cooled in air; reheated 
to 842° C. and quenched in water. Drawn at 532° C. and quenched in oil. S. A. E. 
Steel No. 1035 after recommended heat treatment VII. Sorbite. Etched in 5% 
Nital. 500 X. 

Fig. 94. Steel. 0.50% carbon. Heated to 850° C. and quenched in oil. Drawn 
at 600° C. and quenched in oil. S. A. E. Steel No. 1050 after recommended heat 
treatment VIII. Sorbite. Etched in 5% Nital. 500 X. 



74 



PHOTOMICROGRAPHS OF IRON AND STEEL 



HARDENED AND DRAWN HOT-ROLLED STEEL 




Fig. 95 




Fig. 95. Steel. 0.85% carbon. Heated to 800° C. and quenched in oil. DrawTi 
at 600° C. and quenched in oil. Sorbite. Etched in 5% Nital. 500 X. 

Fig. 96. Steel. L 25% carbon. Heated to 776° C. and quenched in oil. Drawn 
at 600° C. and quenched in oil. Sorbite and small particles of cementite. Etched 
in 5% Nital. 500 X. 



STUDY OF TRANSITION CONSTITUENTS 
ACCORDING TO THE METCALF TEST 

Figs. 97-124 inclusive 

Figs. 97-105 represent a series of photomicrographs showing the transition con- 
stituents of a bar of 0.50% carbon steel heated to a very high temperature at one 
end, followed by quenching the entire bar in water. 

Figs. 106-112 represent a series of photomicrographs showing the transition con- 
stituents of a bar of 0.85% carbon steel heated to a very high temperature at one 
end, followed by quenching the entire bar in water. 

Figs. 113-124 represent a series of photomicrographs showing the transition con- 
stituents of a bar of 1.40% carbon steel heated to a very high temperature at one 
end, followed by quenching the entire bar in water. 



75 



PHOTOMICROGRAPHS OF IRON AND STEEL 



77 



TRANSITION CONSTITUENTS — METCALF TEST 




Fig. 97 




Fig. 98 



Fig. 97. Steel. 0.50% carbon. Microstructure of the bar after heating to a 
temperature exceeding; the critical range and quenching in water. Martensite and 
also the persistence of austenitic grain boundaries. Etched in 5% Nital. 250 X. 
Original magnification, 500 X . 

Fig. 98. Steel. 0.50% carbon. Microstructure of the bar after heating to a 
temperature exceeding the critical range and quenching in water. Martensite. 
Etched in 5% Nital. 250 X. Original magnification, 500 X. 



78 



PHOTOMICROGRAPHS OF IRON AND STEEL 



TRANSITION CONSTITUENTS — METCALF TEST 




^ ir_--*s«5. TS: : 










Fig. 99 





^.^ 






^' 





Fux. lUO 



Fig. 99. Steel. 0.50% carbon. Microstructure of portion of the bar heated to 
a temperature exceeding the critical range and quenching in water. Martensite. 
Etched in 5% Nital. 250 X. Original magnification, 500 X. 

Fig. 100. Steel. 0.50% carbon. Microstructure of portion of the bar heated to 
a temperature exceeding the critical range and quenching in water. Troostite sur- 
rounding martensite grains. Etched in 5% Nital. 250 X. Original magnification, 
500X. 



PHOTOMICROGRAPHS OF IRON AND STEEL 



79 



TRANSITION CONSTITUENTS — METCALF TEST 




Fig. 101 







T-- r •t^f 


|\P|H 




— - ^ 


^^ 


^iBm^ ■ 


.-^^ 


^^|:"- 4-^ •^' 


't * ■ ■ 


i 


^^^^^H^^^H^^^ y 


'te 






^ 








f',j 


•-^ ■' ^ 


i^'Jfl 




9^S-'^'M 


•' i ■■ -^-^ 


"^Stt^m 


ESit«.j»^. 


-,'■>'. . ^^^Bf ^ 




^m 


if^.^^^S 


Wi^jR 




\A .<^r■%.'^ 


lil^^'^ 


1^%^^. 


'vj* 


1^^ 


S^^^'-W'^-* 


'Vw -i. 


W^r^ilii^ 



Fig. 102 



Fig. 101. Steel. 0.50% carbon. Microstructure of portion of the bar heated to 
a temperature within the critical range and quenched in water. Troostite surround- 
ing martensite grains with particles of ferrite embedded in troostite areas. Etched 
in 5% Nital. 250 X. Original magnification, 500 X. 

Fig. 102. Steel. 0.50% carbon. Microstructure of another portion of the bar 
heated to a temperature within the critical range and quenched in water. The two 
large grains, the boundaries of which are ferrite, consist of martensitic areas, sur- 
rounded by troostito-sorbite. Etched in 5% Nital. 250 X . Original magnification, 
500 X. 



80 



PHOTOMICROGRAPHS OF IRON AND STEEL 
TRANSITION CONSTITUENTS — METCALF TEST 




Fig. 103 




Fig. 104 

Fig. 103. Steel. 0.50% carbon. Microstructure of portion of the bar heated to a 
temperature within the critical range and quenched in water. A series of transition 
constituents, namely, martensite, troostite, troostito-sorbite, pearlite and ferrite. 
Etched in 5% Nital. 250 X. Original magnification, 500 X. 

Fig. 104. Steel. 0.50% carbon. Microstructureof portion of the bar heated to a 
temperature within the critical range and quenched in water. A series of transition 
constituents, namely, troostito-sorbite, pearlite and ferrite. Etched in 5% Nital. 
250 X. Original magnification, 500 X. 



I 



PHOTOMICROGRAPHS OF IRON AND STEEL 



81 



TRANSITION CONSTITUENTS — METCALF TEST 




Fig. 105 



Fig. 105. Steel. 0.50% carbon. Microstructure of portion of the bar which 
was heated to a temperature below the critical range and quenched in water. 
A grain of pearHte, the constituents of which are arranged in a Widmanstatten or 
cleavage pattern. Etched in 5% Nital. 750 X. Original magnification, 1000 X. 



82 



PHOTOMICROGRAPHS OF IRON AND STEEL 



TRANSITION CONSTITUENTS — METCALF TEST 







-"^" 


;x 


~^ 




/- 


.'■^i 




- X 


X 


<^ 


/ 


'.'■■ 






"•-t . 


^ 




i' 






< 

- - 7 


«' 


\ 


■' 




- 


d 




\ 


/ ♦ 




■ . 


4' 


^■■'■^.- 



Fig. 106 



Fig. 106. Steel. 0.85% carbon. Microstructure of a portion of the bar heated 
to a temperature near the melting point and quenched in water. Original austenitic 
pattern, — the matrix of which is finely martensitic. Etched in 5% Nital. 375 X. 
Original magnification, 500 X. 



PHOTOMICROGRAPHS OF IRON AND STEEL 



83 



TRANSITION CONSTITUENTS — METCALF TEST 

















X 







s.. 



Fig. 107 



Fig. 107. Steel. 0.85% carbon. Microstrurtiire of a portion of the bar heated 
to a temperature considerably above the critical range and quenched in water. 
Austenito-martensite. Etchedin5% Nital. 375 X. Original magnification, 500 X . 



84 



PHOTOMICROGRAPHS OF IRON AND STEEL 



TRANSITION CONSTITUENTS — METCALF TEST 




Fig. 108 



Fig. 108. Steel. 0.85% carbon. Microstructure of portion of the bar heated 
to a temperature considerably above the critical range and quenched in water. 
Austenito-martensite. The transformation of austenite to martensite took place 
along the octahedral cleavage planes. Etched in 5% Nital. 375 X. Original mag- 
nification, 500 X. 



PHOTOMICROGRAPHS OF IRON AND STEEL 



85 



TRANSITION CONSTITUENTS — METCALF TEST 




Fig. 109 



Fig. 109. Steel. 0.85% carbon. Microstructure of portion of bar heated to 
a temperature considerably above the critical range and quenched in water. 
Troostito-martensite. Etched in 5% Nital. 375 X. Original magnification, 500 X . 



86 



PHOTOMICROGRAPHS OF IRON AND STEEL 



TRANSITION CONSTITUENTS — METCALF TEST 





yi, 








1 


— ,^■^ 

i 


-vi^^jjfl^ 




l^ ^j^pj^. 4 . ■ 






^'.f ■'- ^ > ' 




■ ■>, 


"J* 


2:... .i^::^f--^>M4i^->£?t^- .M 


^ 




. 1 





J^M[?aE3l 


K 





Fig. 110 

Fig. 110. Steel. 0.85% carbon. Microstructure of portion of bar heated to 
a temperature within the critical range and quenched in water. Troostite and small 
areas of martensite. Etched in 5% Nital. 375 X. Original magnification, 500 X. 



\ 



I 

i 



PHOTOMICROGRAPHS OF IRON AND STEEL 



87 



TRANSITION CONSTITUENTS — METCALF TEST 




Fig. Ill 



Fig. 111. Steel. 0.85% carbon. Microstructure of portion of the bar heated to 
a temperature within the critical range and quenched in water. Troostite and sorbite. 
Etched in 5% Nital. 375 X. Original magnification, 500 X. 



88 



PHOTOMICROGRAPHS OF IRON AND STEEL 



TRANSITION CONSTITUENTS — METCALF TEST 




Fig. 112 



Fig. 112. Steel. 0.85% carbon. Microstructure of portion of the bar heated to 
a temperature within the critical range and quenched in water. Transition constitu- 
ents, namely, martensite areas bounded by troostite, sorbite, and pearlite. Etched 
in 5% Nital. 375 X. Original magnification, 500X. 



PHOTOMICROGRAPHS OF IRON AND STEEL 



89 



TRANSITION CONSTITUENTS — METCALF TEST 








Fig. 113 



Fig. 114 




Fig. 115 



Fig. 113. Steel. 1.40% carbon. Microstructure of portion of the bar heated to 
a temperature considerably above the critical range and quenched in water. The 
original twinning pattern in the austenite grain is preserved. Matrix of martensite. 
Etched in 5% Nital. 250 X. Original magnification, 500 X. 

Fig. 114. Steel. 1.40% carbon. Microstructure of portion of the bar heated to 
a temperature considerably above the critical range and quenched in water. 
Troostite precipitated along the original austenite grain boundary, the matrix, 
being martensite. Etched in 5% Nital. 250 X. Original magnification, 500 X. 

Fig. 115. Steel. 1.40% carbon. Microstructure of portion of the bar heated to 
a temperature considerably above the critical range and quenched in water. 
Martensite. Etched in 5% Nital. 250 X. Original magnification, 500 X. 



90 



PHOTOMICROGRAPHS OF IRON AND STEEL 



TRANSITION CONSTITUENTS — METCALF TEST 




Fig. 116 





Fig. 117 



Fig. 118 



Fig. 116. Steel. 1.40% carbon. Microstructure of portion of the bar heated to 
a temperature considerably above the critical range and quenched in water. 
Troostite precipitated along the original austenite grain boundaries. Matrix of 
austenite. Etched in 5% Nital. Original magnification, 500 X. 

Fig. 117. Steel. 1.40% carbon. Microstructure of portion of the bar heated to 
a temperature considerably above the critical range and quenched in water. 
Troostite and martensite. Etched in 5% Nital. 250 X. Original magnification, 
500 X. 

Fig. 118. Steel. 1.40% carbon. Microstructure of portion of the bar heated to 
a temperature below the Acm point and quenched in water. Cementite surrounded 
by troostite areas in martensite matrix. Etched in 5% Nital. 250 X. Original 
magnification, 500 X. 






PHOTOMICROGRAPHS OF IRON AND STEEL 



91 



TRANSITION CONSTITUENTS — METCALF TEST 




Fig. 119 



^^^y 




l*»»wfe^^^ 


m^S 


^4 


l?^sf^ 




^^^^^Mt'^M 


<H> 




^^^^^^^^p 




n^£^ 


^^^^^^^ 


iBtr^^^WE 




a^^^l^^^^^s 




^%l^ 


^M^^^^z 




Fig. 120 



Fig. 121 



Fig. 119. Steel. 1.40% carbon. Microstructure of portion of the bar heated to 
a temperature below the Acm point and quenched in water. Cementite in marten- 
sitic matrix. Etched in 5% Nital. 250 X. Original magnification, 500 X. 

Fig. 120. Steel. 1.40% carbon. Microstructure of portion of the bar heated to 
a temperature within the critical range and quenched in water. Cementite network, 
troostite and martensite. Etched in 5% Nital. 250 X. Original magnification, 
500 X. 

Fig. 121. Steel. 1.40% carbon. Microstructure of portion of the bar heated to 
a temperature below the Acm jaoint and quenched in water. Free cementite sur- 
rounding grains composed of fine martensite. Etched in 5% Nital. 250 X. Origi- 
nal magnification, 500 X. 



92 



PHOTOMICROGRAPHS OF IRON AND STEEL 



TRANSITION CONSTITUENTS — METCALF TEST 




Fig. 122 




Fig. 123 




^^^iM^^MMM 



Fig. 124 



Fig. 122. Steel. 1.40% carbon. Microstructure of portion of the bar heated to 
a temperature below the Acm point. Cementite network, troostite and martensite. 
Etched in 5% Nital. 250 X. Original magnification, 500 X. 

Fig. 123. Steel. 1.40% carbon. Micrcstructure of portion of the bar heated to 
a temperature within the critical range and quenched in water. Cementite network, 
surrounding grains made up of martensite, troostito-sorbite and pearlite. Etched in 
5% Nital. 250 X. Original magnification, 500 X. 

Fig. 124. Steel. 1.40% carbon. Microstructure of portion of the bar heated to 
a temperature below the critical range and quenched in water. Cementite and 
pearlite. Etched in 5% Nital. 250 X. Original magnification, 500 X. 



SPHEROIDIZED STEEL 
Figs. 125 and 126 



93 



PHOTOMICROGRAPHS OF IRON AND STEEL 



95 



SPHEROIDIZED STEEL 




Fig. 125 



Fig. 125. Steel. 1.10% carbon. Partially spheroidized steel. Heated to a tem- 
perature above the critical range, quenched in water, reheated 7 hours at 700° C, 
and cooled in furnace. Globules of cementite in matrix of ferrite with occasional 
trace of pearlite. Etched in 5% Nital. 750 X. Original magnification, 1000 X. 



96 



PHOTOMICROGRAPHS OF IRON AND STEEL 



SPHEROIDIZED STEEL 




Fig. 126. Steel. 1.10% carbon. Fully spheroidized steel. Heated to a tem- 
perature above the critical range, quenched in water, reheated 7 hours at 700° C, 
and cooled in furnace. Globules of cementite in matrix of ferrite. Etched in 5% 
Nital. 750 X. Original magnification, 1000 X . 



GRAPHITIZED CEMENTITE 
Figs. 127 and 128 



97 



PHOTOMICROGRAPHS OF IRON AND STEEL 



99 



GRAPHITIZED CEMENTITE 




Fig. 127 



Fig. 127. Steel. 1.10% carbon. Partially graphitized cementite. Heated 1 
hour at 1000° C. and cooled in furnace. Temper carbon and pearlite. Etched in 
5 % Nital. 375 X . Original magnification, 500 X . 



100 



PHOTOMICROGRAPHS OF IRON AND STEEL 



GRAPHITIZED CEMENTITE 







I:-.'- ■■-■ 




^^.;lp^^^:,.; 


";4-.. -.. 




##-^ ' . 

.:-■■$•::# 

y ■V*;'"';'"'. -"-^I^ 




■ ■-"'■''■ '■■^'', vN''^ \ Vi»i'*> >'i' •'' ''- ' ■- 1'"' '/J 


■,,7'*' . . ;,- . f'r'Mw-^ili 


;|:.fca 










<. * ., •;• .."'V ■'.J",'- »li ^^ . ^ 






\\¥0)^m^^S^:^^%! 




^mm 



Fig. 128 



Fig. 128. Steel. 1.10% carbon. Graphitized cementite. Heated 2 hours at 
1050° C. and cooled in furnace. Temper carbon surrounded by ferrite areas in 
grains of sorbito-pearlite. Etched in 5% Nital. 375 X. Original magnification, 
500 X. 



OVERHEATED AND BURNT STEEL 
Figs. 129 and 130 



101 



PHOTOMICROGRAPHS OF IRON AND STEEL 



103 



OVERHEATED AND BURNT STEEL 



r^ '^ > ''v 









Fig. 129 



Fig. 129. Steel. 0.50% carbon. Overheated steel. Heated for 5 hours at 
1100° C, and cooled in furnace. Large grains of sorbito-pearlite surrounded by a 
membrane of ferrite. Etched in 5% Nital. 75 X. Original magnification, 100 X. 



104 



PHOTOMICROGRAPHS OF IRON AND STEEL 



OVERHEATED AND BURNT STEEL 




if', ' * • ', ^Afe :'.' - 'f .''.':-^y^^' //■*/, ■•.•'V/lii^W^-.-.i'''^<^j 




Fig. 130 

Fig. 130. Steel. 1.25% carbon. Burnt steel. Heated to a sintering heat and 
quenched in water. The grain boundaries of the metal have been badly oxidized. 
Lightly etched in 5% Nital. 375 X. Original magnification, 500 X. 



GRAIN GROWTH IN MILD STEEL 
Figs. 131-133 inclusive 



105 



PHOTOMICROGRAPHS OF IRON AND STEEL 



107 



GRAIN GROWTH IN MILD STEEL 




Fig. 131 



Fig. 131. Steel. 0.08% carbon. Subjected to Brinell Ball test under a pressure 
of 3000 kilograms, heated 7 hours at 650° C, and cooled slowly in furnace. Verti- 
cal section through bottom of spherical depression. Etched in 12% Nital. 5.5 X. 

A — Metal too severely strained to grow. 

B — Junction between critically strained and unstrained metal. 

C — Critically strained metal. 

D — Unstrained metal. 



108 



PHOTOMICROGRAPHS OF IRON AND STEEL 



GRAIN GROWTH IN MILD STEEL 






c'-^^^^'-'^ : 



>^^>^..-. 



ttri^- 'tr 




-'< 









^■:^< \ 



y^i 



iS^SrS#ii'i^- 



■J --.-^ w:i2<«t, >-^^ 








\r^-y:i 



.7 :' 



Fig. 132 

Fig. 132~. Steel. 0.08% carbon. Grain growth in low carbon steel. Micro- 
structure at Section B shown in Fig. 131 illustrates junction between critically 
strained and unstrained metal. Etched in 5% Nital. 75X. Original magnifica- 
tion, 100 X. 



PHOTOMICROGRAPHS OF IRON AND STEEL 



109 



GRAIN GROWTH IN MILD STEEL 




Fig. 133 



Fig. 133. Steel. 0.08% carbon. Grain growth in low carbon steel. Micro- 
structure at Section C shown in Fig. 131 illustrates critically strained material. 
Etched in 5% Nital. 75 X. Original magnification, 100 X. 



CASE-HARDENED CARBON STEEL 

AND 
HEAT TREATED CASE-HARDENED CARBON STEEL 

Figs. 134-142 inclusive 



111 



PHOTOMICROGRAPHS OF IRON AND STEEL 



113 



CASE-HARDENED CARBON STEEL 



1 


SB 


^p 


^^^^^ 












Fig. 134 



Fig. 135 



Fig. 134. Steel. 0.15% carbon. Case-hardened with eutectoid case. Specimen 
cooled slowly in box after case-hardening. Etched in 5% Nital. 50 X. Original 
magnification, 100 X. 

Fig. 135. Steel. 0.15% carbon. Heat treated case-hardened 0.15% carbon steel 
(same steel as shown in Fig. 134). Heated to 980° C, and quenched in water to 
refine core; heated to 825° C, and quenched in water to refine case. Etched in 5% 
Nital 50 X. Original magnification, 100 X. 



114 



PHOTOMICROGRAPHS OF IRON AND STEEL 



CASE-HARDENED CARBON STEEL 










Fig. 136 




Fig. 137 



Fig. 136. Steel. 0.15% carbon. Case-hardened. Free cementite in case. Cooled 
slowly from case-hardening treatment. Etched in 5% Nital. 50 X. Original magni- 
fication, 100 X. 

Fig. 137. Steel. 0.15% carbon. Heat treated case-hardened steel. (Same steel 
as shown in Fig. 136.) Heated to 980° C, and quenched in water to refine the core. 
Heated to 825° C, and quenched in water to refine the case. The presence of free 
cementite in the case caused cracks to develop during the quenching operation. 
Etched in 5% Nital. 50 X. Original magnification, 100 X. 



PHOTOMICROGRAPHS OF IRON AND STEEL 



115 



CASE-HARDENED CARBON STEEL 




Fig. 138 



Fig. 138. Steel. Case-hardened. Example of phosphorus segregation in case of 
hyper-eutectoid composition. The phosphorus rich area has not absorbed carbon 
during the carburizing process. Etched in 5% Nital. 50 X. Original magnifica- 
tion, 100 X. 



116 



PHOTOMICROGRAPHS OF IRON AND STEEL 
CASE-HARDENED CARBON STEEL 













Fig. 139 



Fig. 140 





.'^^hB"l 



Fig. 141 



Fig. 142 



Will give a martensitic case in hardening. 
Will give soft troostitic spots in hardening. 



Fig. 139. Case of normal steel. 
Magnified 50 diameters. 

Fig. 140. Case of abnormal steel. 
Magnified 50 diameters. 

Fig. 141. Hyper-eutectoid zone of normal steel. Magnified 200 diameters. 

Fig. 142. Hyper-eutectoid zone of abnormal steel. Magnified 200 diameters. 
(E. W. Ehn.) Reproduced from Sauveur's Metallography and Heat Treatment of 
Iron and Steel by permission. 



DECARBURIZED STEEL 
Fig. 143 



117 



PHOTOMICROGRAPHS OF IRON AND STEEL 



119 



DECARBURIZED STEEL 




Fig. 143 



Fig. 143. Steel. 1.40% carbon. Decarburized. Heated 5 hours at a tempera- 
ture considerably above the critical range and slowly cooled in furnace. The edge of 
the specimen is practically carbonless. Etched in 5% Nital. 50 X. Original mag- 
nification, 100 X. 



ALLOY STEEL 

A. NICKEL STEEL 
Cast, forged, annealed and after recommended heat treatment 

Figs. 144-148 inclusive 



121 



PHOTOMICROGRAPHS OF IRON AND STEEL 



123 



ALLOY STEEL — NICKEL STEEL 





W 


•■• » >- 


■1 




m 








W 




s -:'$ 


W^-'' ■■ ■ 








t- 






■1 


im?:: 






,1 








Fig. 144 



Fig. 145 




Fig. 146 



Fig. 144. Nickel steel. Cast. 0.30% carbon; 3.50% nickel. Fine Widman- 
statten structure. Etched in 5% Nital. 50X. Original magnification, 100 X. 

Fig. 145. Nickel steel. Hot-rolled. 0.30% carbon; 3.50% nickel. Banded struc- 
ture. Etched in 5% Nital. 50X. Original magnification, 100 X . 

Fig. 146. Nickel steel. Annealed. 0.30% carbon; 3.50% nickel. Etched in 
5% Nital. 100 X. 



124 



PHOTOMICROGRAPHS OF IRON AND STEEL 



ALLOY STEEL — NICKEL STEEL 




Fig. 147 




Fig. 148 



Fig. 147. Nickel steel. Heat treated. 0.30% carbon; 3.50% nickel. Normal- 
ized at 913° C. Heated to 902° C, and quenched in oil. Drawn at 538° C. S. A. E. 
Steel No. 2330 after recommended heat treatment VII. Etched in 5% Nital. 
600 X. 

Fig. 148. Nickel steel. Hot-rolled. 0.30% carbon; 5.00% nickel. Etched in 
6% Nital. 100 X. 



B. CHROMIUM STEEL 
Annealed and after recommended heat treatment 

Figs. 149-154 inclusive 



125 



PHOTOMICROGRAPHS OF IRON AND STEEL 



127 



ALLOY STEEL — CHROMIUM STEEL 



Ml 




1^ 


l^pl^ 




^ 




Fig. 149 



Fig. 150 




Fig. 151 



Fig. 149. Chromium steel. Annealed. 0.40% carbon; 0.95% chromium. 
S. A. E. Steel No. 5140 armealed. Etched in 5% Nital. 500 X. 

Fig. 150. Chromium steel. Heat treated. 0.40% carbon; 0.95% chromium. 
Normalized at 913° C, reheated to 843° C, quenched in oil. S. A. E. Steel No. 5140 
after heat treatment VIII. Drawn at 538° C. Etched in 5% Nital. 500X. 

Fig. 151. Chromium steel. Annealed. 1.00% carbon; 1.35% chromium. S. A. E. 
Steel No. 52100 annealed. Etched in 5% Nital. 500 X. 



128 



PHOTOMICROGRAPHS OF IRON AND STEEL 



ALLOY STEEL — CHROMIUM STEEL 




Fig. 152 



Fig. 153 




Fig. 154 



Fig. 152. Chromium steel. Heat treated. 1.00% carbon; 1.35% chromium. 
Heated to 829° C, quenched in oil. Drawn at 538° C. S. A. E. Steel No. 52100 
after recommended heat treatment VI. Etched in 5% Nital. 500X. 

Fig. 153. Stainless steel. Annealed. 0.30% carbon; 12.00% chromium. Etched 
in Marble's reagent. 500 X. 

Fig. 154. Stainless steel. Hardened and tempered. 0.30% carbon; 12.00% 
chromium. Etched in Marble's reagent. 500 X. 



C. NICKEL-CHROMIUM STEEL 
Annealed and after recommended heat treatment 

Figs. 155-158 inclusive 



129 



PHOTOMICROGRAPHS OF IRON AND STEEL 



131 



ALLOY STEEL — NICKEL-CHROMIUM STEEL 




^^M 


^ 


^^^^^^P 


^^S 


s 


^^^^8 




i 


^^B 




^m 


^^^^^^^g 




^B 


^^^^^^^^^^ 


^^^p 


m 


^^^^s 




^ 


^^^^^^ 



Fig. 155 



Fig. 156 




Fig. 157 



Fig. 158 



Fig. 155. Nickel-chromium steel. Annealed. 0.30% carbon; 1.75% nickel; 
1.00% chromium. S. A. E. Steel No. 3230 annealed. Etched in 5% Nital. 500X. 

Fig. 156. Nickel-chromium steel. Heat treated. 0.30% carbon; 1.75% nickel; 
1.00% chromium. Normalized at 913° C. Heated to 829° C, quenched in oil. 
Tempered at 191° C. S. A. E. Steel No. 3230 after recommended heat treatment 
VII. Etched in 5% Nital. 500 X. 

Fig. 157. Nickel-chromium steel. Annealed. 0.35% carbon; 3.50% nickel; 
1.50% chromium. S. A. E. Steel No. 3335 annealed. Etched in 5% Nital. 500X. 

Fig. 158. Nickel-chromium steel. Heat treated. 0.35% carbon; 3.50% nickel; 
1.50% chromium. Normalized at 899° C. Heated to 746° C, cooled slowly in fur- 
nace, reheated to 743° C, quenched in oil. Drawn at 538° C. S. A. E. Steel No. 3335 
after recommended heat treatment VIII. Etched in 5% Nital. 500 X. 



D. CHROMIUM-VANADIUM STEEL 

Annealed and after recommended heat treatment 

Figs. 159-162 inclusive 



133 



PHOTOMICROGRAPHS OF IRON AND STEEL 
ALLOY STEEL — CHROME-VANADIUM STEEL 



135 




Fig. 159 



Fig. 160 




«^^J^J 


M 


^ 




gSuBci^^v^p 


M 




m 


^m 






^ 


^^^K^i^^ 


1 


1 


^w2g 




i 


^^^^^ 


i 


m 






1 


^^^^1^ 

S^^^^^^ 


1 


1 




^^%^^S^ 


1 




W 


^wl 






^r 




w 


^^ 


^^ 




y& 



Fig. 161 



Fig. 162 



Fig. 
mium; 
500 X. 

Fig. 
mium ; 



159. Chrome-vanadium steel. Annealed. 0.35% carbon; 0.95% chro- 
0.18% vanadium. S. A. E. Steel No. 6135 annealed. Etched in 5% Nital. 



160. Chrome-vanadium steel. Heat treated. 0.35% carbon; 0.95% chro- 
0.18% vanadium. Normalized at 913° C, reheated to 704° C, cooled slowly. 
Reheated to 871° C, quenched in oil. Drawn at 533° C. S. A. E. Steel No. 6135 
after recommended heat treatment VIII. Etched in 5% Nital. 500 X. 

Fig. 161. Chrome-vanadium steel. Annealed. 1.00% carbon; 0.90% chro- 
mium; 0.18% vanadium. S. A. E. Steel No. 6195 annealed. Etched in 5% Nital. 

500 X. 

Fig. 162. Chrome-vanadium steel. Heat treated. 1.00% carbon; 0.90% chro- 
mium; 0.18% vanadium. Heated to 829° C, quenched in oil. Drawn at 538° C. 
S. A. E. Steel No. 6195 after recommended heat treatment VI. Etched in 5% Nital. 
500 X. 



E. MOLYBDENUM STEEL 

Annealed and after recommended heat treatment 

Figs. 163 and 164 



137 



PHOTOMICROGRAPHS OF IRON AND STEEL 



139 



ALLOY STEEL — MOLYBDENUM STEEL 




Fig. 163 





^^^^^^^^^^M 




^^H 


ni^^M 


^^^^^^S 




^^^^^^^^^m 




^^H 



Fig. 164 



Fig. 163. Molybdenum steel. Annealed. 0.40% carbon; 0.95% chromium; 
0.20% molybdenum. S. A. E. Steel No. 4140 annealed. Etched in 5% Nital. 

500 X- 

Fig. 164. Molybdenum steel. Heat treated. 0.40% carbon; 0.95% chromium; 
20% molybdenum. Normalized at 927° C, reheated to 704° C, cooled slowly, re- 
heated to 857° C, quenched in oil. Drawn at 538° C. S. A. E. Steel No. 4140 after 
recommended heat treatment VIII. Etched in 5% Nital. 500 X. 



F. HADFIELD MANGANESE STEEL 

Cast and after recommended heat treatment 

Figs. 165-167 inclusive 



141 



PHOTOMICROGRAPHS OF IRON AND STEEL 



143 



ALLOY STEEL — MANGANESE STEEL 





Fig. 165 



Fig. 166 



»' ■ . 




/ 




'V -^/ 




f'f ~, 










\% ■ V 



Fig. 167 



Fig. 165. Manganese steel. Cast. 1.00% carbon; 12.00% manganese. Free 
carbides in matrix of austenite. Etched in 5% Nital. 50 X. Original magnifica- 
tion, 100 X. 

Fig. 166. Manganese steel. Cast. Same as in Fig. 165, more highly magnified. 
Carbides of manganese in austenite matrix. Deformation lines in austenite. 

Fig. 167. Manganese steel. Cast. Heat treated. 1.00% carbon; 12% man- 
ganese. Heated to 1100° C. and quenched in cold water. Grains of austenite. 
Deformation lines in austenite grain. Etched in 5% Nital. 250 X. Original mag- 
nification, 500 X. 



SILICON STEEL 

(AS CAST) 

Fig. 168 



145 



PHOTOMICROGRAPHS OF IRON AND STEEL 



147 



ALLOY STEEL — SILICON STEEL 




Fig. 168 



Fig. 168. Silicon steel. Cast. 0.15% carbon; 4.50% silicon. Typical large 
grain size of high sihcon steel. Etched in 5% Nital. 50 X. Original magnifica- 
tion, 100 X. 



SILICO-MANGANESE STEEL 

Annealed and after recommended heat treatment 

Figs. 169 and 170 



149 



PHOTOMICROGRAPHS OF IRON AND STEEL 



151 



ALLOY STEEL — SILICO-MANGANESE STEEL 




Fig. 169 




Fig. 170 



Fig. 
ganese 
500 X. 

Fig. 
ganese 



169. Silico-manganese steel. Annealed. 0.50% carbon; 0.75% man- 
2.00% silicon. S. A. E. Steel No. 9260 annealed. Etched in 5% Nital. 



170. Silico-manganese steel. Heat treated. 0.50% carbon; 0.75% man- 
2.00% silicon. Normalized at 927° C, reheated to 763° C, cooled slowly, 
reheated to 885° C, quenched in oil. Drawn at 538° C. S. A. E. Steel No. 9260 
after recommended heat treatment VIII. Etched in 5% Nital. 500 X. 



CHROME-TUNGSTEN STEEL 

(HIGH-SPEED STEEL) 

Cast, annealed, and after recommended heat treatment 

Figs. 171-177 inclusive 



153 



PHOTOMICROGRAPHS OF IRON AND STEEL 



155 



ALLOY STEEL — CHROME-TUNGSTEN STEEL 





Fk;. 171 



Fig. 172 





Fig. 173 



Fig. 174 



Fig. 171. High-speed steel. Cast. 0.60% carbon; 17.00% tungsten; 3.50% 
chromium. Etched in 5% Nital. 250X. Original magnification, 500 X. 

Fig. 172. Same spot as in Fig. 171. After repolishing and etching in Murakami's 
reagent. 250 X. Original magnification, 500 X. 

Fig. 173. Another spot on specimen shown in Fig. 172. After etching in Mura- 
kami's reagent. 250 X. Original magnification, 500 X. 

Fig. 174. Another spot on specimen shown in Fig. 172. After etching in Mura- 
kami's reagent. 250 X . Original magnification, 500 X . 



156 



PHOTOMICROGRAPHS OF IRON AND STEEL 



ALLOY STEEL — CHROME-TUNGSTEN STEEL 




P^~< 







Fig. 176 




Fig. 177 

Fig. 175. High-speed steel. Annealed. 0.60% carbon; 17.00% tungsten; 3.50% 
chromium. Carbides of chromium and tungsten in a sorbitic matrix. Etched in 5% 
Nital. 500 X. 

Fig. 176. High-speed steel. Heat treated. 0.60% carbon; 17.00% tungsten; 
3.50% chromium. Preheated in a salt bath to 926° C, then heated in a second 
salt bath to 1204° C, and quenched in a third salt bath at 593° C. Carbides of 
tungsten and chromium in austenitic matrix. Etched in 1% Nital and subse- 
quently in Kourbatoff's reagent. 1000 X. 

Fig. 177. High-speed steel. Heat treated. 0.60% carbon; 17.00% tungsten; 
3.50% chromium. Preheated to 816° C, heated to 1288° C, quenched in oil, and 
drawn at 593° C. Etched in 1% Nital and subsequently in KourbatofiF's reagent. 
1000 X. 



J. SPECIAL ALLOY STEEL CONTAINING TUNGSTEN 
AND CHROMIUM 

Possessing properties of hardness after recommended heat treatment. 

Seminole Steel. 

Figs. 178-180 inclusive 



157 



PHOTOMICROGRAPHS OF IRON AND STEEL 159 



ALLOY STEEL — CHROME-TUNGSTEN STEEL 




Fig. 178 

Fig. 178. Seminole steel as received. Containing tungsten and chromium. 
Etched in 5% Nital. 500 X. 



160 



PHOTOMICROGRAPHS OF IRON AND STEEL 



ALLOY STEEL — CHROME-TUNGSTEN STEEL 




Fig. 179 




Fig. 180 



Fig. 179. Seminole steel. Hardened. Containing tungsten and chromium. 
Etched in 5% Nital. 500 X. 

Fig. 180. Seminole steel. Hardened and tempered. Containing tungsten and 
chromium. Etched in 5% Nital. 500 X. This steel possesses properties of hard- 
ness and toughness. 



K. NON-SCALING STEEL 

Hadfield Era A.T.V. AUoy Steel 

Fig. 181 



161 



PHOTOMICROGRAPHS OF IRON AND STEEL 



163 



ALLOY STEEL — HADFIELD ERA — A.T.V. NON-SCALING STEEL 




Fig. 181 



Fig. 181. Hadfield Era — A.T.V. Non-scaling steel after heating to 926° C. 
and cooling in air. Etched in 5% Nital. 500 X. 



CASE-HARDENED ALLOY STEEL AFTER RECOMMENDED 
HEAT TREATMENT 

1. Nickel steel, Fig. 182 

2. Chromium steel, Fig. 183 

3. Nickel-chromium steel. Fig. 184 

4. Molybdenum steel, Fig. 185 

5. Chrome-vanadium steel, Fig. 186 



165 



PHOTOMICROGRAPHS OF IRON AND STEEL 



167 



CASE-HARDENED ALLOY STEEL 




Fig. 182 




Fig. 182. Nickel steel. Case-hardened and heat treated. 0.20% carbon; 5.00% 
nickel. Cooled slowly in box after case-hardening and subsequently subjected to 
double heat treatment. 50 X. Original magnification, 100 X. 

Fig. 183. Chromium steel. Case-hardened and heat treated. 0.20% carbon; 
0.75% chromium. Carburized at 913° C, cooled in box. Reheated to 885° C, 
quenched in oil; reheated to 743° C, quenched in oil. S. A. E. Steel No. 5120 after 
recommended heat treatment V. Drawn at 191° C. Etched in 5% Nital. 50 X. 
Original magnification, 100 X. 



168 



PHOTOMICROGRAPHS OF IRON AND STEEL 



CASE-HARDENED ALLOY STEEL 





Fig. 184 



Fig. 185 



Fig. 184. Nickel-chromium steel. Case-hardened and heat treated. 0.17% car- 
bon; 3.50% nickel; 1.50% chromium. Carburized 7 hours at 885° C, cooled in box. 
Reheated to 843° C, quenched in oil; reheated to 759° C, quenched in oil. Tem- 
pered at 191° C. S. A. E. Steel No. 3312 after recommended heat treatment V. 
Etched in 5% Nital. 50X. Original magnification, 100 X. 

Fig. 185. Molybdenum steel. Case-hardened and heat treated. 0.15% carbon; 
1.50% nickel; 0.25% molybdenum. Carburized at 885° C, cooled in box. Re- 
heated to 843° C, quenched in oil; reheated to 759° C, quenched in oil. Tempered 
at 191° C. S. A. E. Steel No. 4615 after recommended heat treatment V. Etched 
in 5% Nital. 50 X. Original magnification, 100 X. 



PHOTOMICROGRAPHS OF IRON AND STEEL 



169 



CASE-HARDENED ALLOY STEEL 






y/7^ 




Fig. 186 



Fig. 186. Chrome-vanadium steel. Case-hardened and heat treated. 0.20% 
carbon; 0.95% chromium; 0.18% vanadium. Carburized at 913° C, cooled in box. 
Reheated to 885° C, quenched in oil; reheated to 742° C, quenched in oil. Tem- 
pered at 191° C. S. A. E. Steel No. 6120 after recommended heat treatment V. 
Etched in 5% Nital. 50 X. Original magnification, 100 X. 



ANNEALED NITRALLOY 

(STEEL USED FOR NITRIDING) 

AND 

NITRIDED STEELS 

Figs. 187-193 inclusive 



171 



PHOTOMICROGRAPHS OF IRON AND STEEL 



173 



NITRALLOY AND NITRIDED NITRALLOY 




Fig. 187 




Fig. 18S 



Fig. 187. Nitralloy. Annealed. 0.36% carbon; 0.51% manganese; 0.27% sili- 
con; 1.23% aluminum; 1.49% chromium; 0.010% sulphur; 0.013% phosphorus; 
0.18% molybdenum. Etched in 5% Nital. 500 X. 

Fig. 188. Nitralloy after subjected to nitriding process. Etched in 5% Nital. 
50 X. Original magnification, 100 X. 



174 



PHOTOMICROGRAPHS OF IRON AND STEEL 



NITRIDED NITRALLOY 




Fig. 189 




Fig. 190 



Fig. 191 



Fig. 189. Microstructureof section J.. Shown in Fig. 188. Etchedin 5% Nital. 
250 X. Original magnification, 500 X. 

Fig. 190. Microstructure of section B. Shown in Fig. 188. Etched in 5% Nital. 
250 X. Original magnification, 500 X. 

Fig. 191. Microstructure of section C. Shown in Fig. 188. Etched in 5% Nital. 
250 X. Original magnification, 500 X. 



PHOTOMICROGRAPHS OF IRON AND STEEL 



175 



NITRIDED NITRALLOY 




Fig. 192 




Fig. 193 



Fig. 192. Microstructure of section D. Shown in Fig. 188. Etched in 5% Nital. 
500 X. 

Fig. 193. Microstructure of section E. Shown in Fig. 188. Metal unaffected 

by nitriding. Etched in 5% Nital. 500 X. 



f 



CAST IRON 
(GRAY IRON) 

Figs. 194-201 inclusive 



177 



PHOTOMICROGRAPHS OF IRON AND STEEL 



]79 



GRAY CAST IRON 





Fig. 194 



Fig. 195 








Fig. 190 



Fig. 197 



Fig. 194. Gray cast iron. No combined carbon. Graphite and ferrite. Etched 
in 5% Nital. 250 X. Original magnification, 500 X. 

Fig. 195. Gray ca.st iron. No combined carbon. Graphite, ferrite and steadite. 
Etched in 5% Nital. 250 X. Original magnification, 500 X. 

Fig. 196. Gray cast iron. Hypo-eutectoid matrix, containing about 0.40% com- 
bined carbon. Graphite, pearlite, ferrite and steadite. 

Fig. 197. Gray cast iron. Hypo-eutectoid matrix, containing about 0.60% com- 
bined carbon. Graphite, pearlite and ferrite. 250 X. Original magnification, 
500X. 



180 



PHOTOMICROGRAPHS OF IRON AND STEEL 



GRAY CAST IRON 





Fig. 198 



Fig. 199 





Fig. 200 



Fig. 201 



Fig. 198. Gray cast iron. Hypo-eutectoid matrix, containing about 0.60% com- 
bined carbon. Graphite, pearlite, steadite and ferrite. Etchedin5% Nital. 250 X. 
Original magnification, 500 X. 

Fig. 199. Gray cast iron. Eutectoid matrix, containing about 0.85% combined 
carbon. Graphite and pearUte. Etched in 5% Nital. 250 X. Original magnifica- 
tion, 500 X. 

Fig. 200. Gray cast iron. Eutectoid matrix, containing about 0.85% combined 
carbon. Graphite, pearlite and steadite. Etched in 5% Nital. 250 X. Original 
magnification, 500 X. 

Fig. 201. Gray cast iron. Hyper-eutectoid matrix, containing about 1.25% 
combined carbon. Graphite, sorbite and cementite. Etched in 5% Nital. 250 X. 
Original magnification, 500 X. 



MOTTLED CAST IRON 
Fig. 202 



181 



PHOTOMICROGRAPHS OF IRON AND STEEL 183 



MOTTLED CAST IRON 




Fig. 202 

Fig. 202. Mottled cast iron. Cementite, pearlite and graphite. Etched in 5% 
Nital. 250 X. Original magnification, 500 X. 



WHITE CAST IRON 
Figs. 203 and 204 



185 



PHOTOMICROGRAPHS OF IRON AND STEEL 



187 



WHITE CAST IRON 




^K5ib*! 



Fig. 203 



Fig. 203. White cast iron. Cementite and pearlite. Etched in 5% Nital. 
375 X. Original magnification, 500 X- 



188 



PHOTOMICROGRAPHS OF IRON AND STEEL 



WHITE CAST IRON 







Fig. 204 



Fig. 204. White cast iron. Cementite and pearlite. Etched in 5% Nital. 
375 X. Original magnification, 500 X. 



MALLEABLIZED CAST IRON 
Figs. 205 and 206 



189 



PHOTOMICROGRAPHS OF IRON AND STEEL 191 



PARTIALLY MALLEABLIZED CAST IRON 




Fig. 205 

Fig. 205. Cast iron. Partially malleablized. Ferrite, temper-carbon and sorbito- 
pearlite. Etched in 5% Nital. 375 X. Original magnification, 500 X . 



192 



PHOTOMICROGRAPHS OF IRON AND STEEL 



FULLY MALLEABLIZED CAST IRON 




Fig. 206 



Fig. 206. Cast iron. Fully malleablized. Ferrite and temper-carbon. Etched 
in 5% Nital. 375 X. Original magnification, 500 X. 



MANGANESE SULPHIDE IN CAST IRON 
Fig. 207 



193 



PHOTOMICROGRAPHS OF IRON AND STEEL 



195 



MANGANESE SULPHIDE IN MALLEABLIZED CAST IRON 




Fig. 207 



Fig. 207. Manganese Sulphide in partially malleablized cast iron. Rounded 
particles of dove-gray manganese sulphide in ferrite. Temper-carbon and sorbito- 
pearlite present. Etched in 5% Nital. 500X. 



PHOSPHIDE EUTECTIC IN CAST IRON 
Figs. 208-210 inclusive 



197 



PHOTOMICROGRAPHS OF IRON AND STEEL 



199 



PHOSPHIDE EUTECTIC 




Fig. 208 



^ir'grg ^ W > . - N- ' t.v. j^ ' ^^ " ; ' \ifl^^t ^ 




Fig. 209 



Fig. 208. Phosphide eutectic after etching in 5% Nital. 250 X. Original mag- 
nification, 500 X. 

Fig. 209. Same as in Fig. 208, after repolishing and etching in sodium picrate. 
250 X. Original magnification, 500 X. 



200 



PHOTOMICROGRAPHS OF IRON AND STEEL 



PHOSPHIDE EUTECTIC 




Fig. 210 

Fig. 210. Same spot as shown in Fig. 209, after repolishing and heat-tinting.* 
The dark-colored plates in the print represent a deep lavender color, — phos- 
phorus rich areas. The bright-colored plates in the eutectic represent a j^ellow- 
ish-red color — cementite areas. 250 X. Original magnification, 500 X. 



* The polished specimen was placed on a hot plate and heated by a Bunsen gas burner until the 
phosphorus rich areas were tinted a deep lavender. 



CHILLED CAST IRON 

Showing a series of Photomicrographs of a chilled casting 
Figs. 211-213 inclusive 



201 



PHOTOMICROGRAPHS OF IRON AND STEEL 



203 



CHILLED CAST IRON 








Fig. 211 



Fig. 212 




Fig. 213 



Fig. 211. Microstriicture of chilled face of gray iron casting. Etched in 5% 
Nital. 250 X. Original magnification, 500 X. 

Fig. 212. Microstructure of junction of chill and gray iron. Etched in 5% 
Nital. 250 X. Original magnification, 500 X. 

Fig. 213. Microstructure of gray iron. Etched in 5% Nital. 250x. Original 
magnification, 500 X. 



SEMI-STEEL 

Comparative microstructures of gray cast iron with 

a eutectoid matrix, Fig. 214, and a semi-steel 

with a eutectoid matrix, Fig. 215 



205 



PHOTOMICROGRAPHS OF IRON AND STEEL 



207 



SEMI-STEEL 



^n^ 




m 


F. * ^M 


^"1*^ 




P 0^^; 




m 




m 



Fig. 214 




Fig. 215 



Fig. 214. Gray cast iron. Eutectoid matrix. Large graphite plates, sorbito- 
pearlite, and steadite. Etched in 5% Nital. lOOX. 

Fig. 215. Semi-steel. Eutectoid matrix. Small graphite plates, sorbito-pearlite 
and traces of steadite. Etched in 5% Nital. 100 X. 



CAST IRON CONTAINING SPECIAL ELEMENTS 
Figs. 216-218 inclusive 



209 



PHOTOMICROGRAPHS OF IRON AND STEEL 



211 



SPECIAL ELEMENTS IN GRAY CAST IRON 












Fig. 216 




Fig. 217 

Fig. 216. Gray cast iron. Hypo-eutectoid matrix. 3.16% total carbon; 2.63% 
silicon. Etched in 5% Nital. lOOX. 

Fig. 217. Nickel. Gray cast iron. Hypo-eutectoid matrix. 3.17% total car- 
bon; 1.14% silicon; 2.83% nickel. Etched in 5% Nital. lOOX. 



212 PHOTOMICROGRAPHS OF IRON AND STEEL 



SPECIAL ELEMENTS IN GRAY CAST IRON 




Fig. 218 

Fig. 218. Nickel-Chromium. Gray cast iron. Hypo-eutectoid matrix. 3.11% 
total carbon; 2.20% silicon; 1.11% nickel, and 0.38% chromium. Etched in 5% 
Nital. 100 X. 



APPENDICES 



APPENDIX A 

THE PREPARATION OF METALLO GRAPHIC 
SPECIMENS* 

By H. M. Boylston, Professor of Metallurgy, Case School of Applied Science, 

Cleveland, Ohio. 

Selection of Specimen. — Metallographic specimens should be so selected 
as to be representative of the metal from which they are taken. Where the 
piece has failed in service it is important that a specimen should be taken 
from near the failure and one considerably distant from it for comparison or 
samples may sometimes be obtained from similar pieces which have stood up 
well in service. 

When samples are taken from near a fracture, the metal very close to the 
fracture itself should be examined. The fracture edge should not be bevelled 
and sometimes it is well to electroplate the fractured surface with copper 
(Rosenhain), in order to protect the fracture from bevelling during subsequent 
grinding and polishing operations. Embedding the plated specimen in fusible 
metal, as explained below, is sometimes advisable. 

Note should be made of the location of the specimen in the piece and the 
relation of the surface to be polished to the direction of forging and rolling. 
A sketch is very helpful in this connection. 

Removal of Specimen. — Specimens are generally cut off with a hack saw. 
Tough steels, like manganese steel and other austenitic material, hardened 
steels, or even white cast iron, wliich cannot be cut with a hack saw, may be 
cut easily with a thin alundum or carborundum disc, three-thirty-seconds 
of an inch thick and running in water, if it is necessary to prevent tempering. 
If no cutting disc is available brittle specimens may be broken with a hammer, 
although this means a rough surface to grind down later. 

Dimensions of Specimen. — Much time is saved by keeping the specimen 
small within reasonable lunits. A one-half inch square or round piece is a 
good size unless the microscope is of such construction that a larger piece is 
necessary in order to prevent it from slipping through the stage. It is much 
easier and quicker to polish four pieces each one-half inch square than it is 
to polish one piece one inch square. The thickness of the specimen should 
be less than the other dimensions, if possible, since the thicker the specimen 
the more difficult it is to hold it on the grinding and polishing wheels without 
rounding the surface. A one-half inch square or round piece should be prefer- 
ably not over three-eighths inch thick. Very small specimens may be embedded 

* Printed from the American Society for Steel Treating handbook, by permission. 

215 



216 APPENDIX A 

in some fusible metal, sealing wax, fiber or by mounting in suitable metal 
clamps. (See Figs. 1, 2, and 3.) By these means the finest wire, turnings and 
even filings may be polished and examined. The following alloy, suggested 
by Champion and Ferguson, which melts in boiling water, is very useful in 
mounting small specimens: 

Bismuth 50 parts by weight 

Lead 30 parts by weight 

Tin 25 parts by weight 

Zinc 3 parts by weight 





^ 


f 


/I 




13 

'A 


/L 


/Wm 


wi 


(/ 


f 


B 




B 



Fig. 1 Fig. 2 Fig. 3 

Figs. 1 and 3. — Polishing Clamps for Specimeas. Fig. 2. — Container for 
Mounting Specimens in Balsam or Low Melting Alloys. 

The inexpensive small iron cups known in the trade as "malleable gas caps," 
either three-eighths or one-quarter inch size, are very useful for holding the 
alloy and the specimen. The cap is heated to about 392 degrees Fahr. by 
placing it on an electric stove or on an iron plate heated by a bunsen burner. 
The fusible alloy is then placed in it and melted. The temperature is then 
reduced until the cap and metal are just a little above 212 degrees Fahr. and 
the specimen to be polished is then pressed into the metal. The cap and its 
contents may then be solidified and cooled, and polished like any other specimen. 
If the nature of the specimen will allow it, it should be dipped into a saturated 
solution of zinc chloride before placing in the alloy. The zinc chloride acts 
as a flux and cleans the surface of the specimen so that a better joint is made 
between it and the mounting metal. It is obvious that any metal that alloys 
with the mounting metal cannot be mounted in this way. 

Grinding and Polishing. — It was at one time thought necessary to grind 
and polish by hand, but this is a tedious and slow method. Power grinduig 
and polishing have now been in successful use for many years and are recom- 
mended except where very soft metals or alloys are to be prepared, when special 
precautions have to be observed. Grinding and polishing are generally carried 
out in three or more steps: 

a. Grinding or filing to obtain a flat surface. 

6. Rough polishing. 

c. Fine polishing generally including two or more steps. 

Grinding. — A medium fine and medium hard grinding wheel is generally 
used for this purpose. Grade 80-P alundum wheel or No. 2 French emery 



APPENDIX A 217 

paper gives good results. Some grind on a coarse file, but this is preferably- 
restricted to soft metals. Grinding wheels may be mounted either vertically 
or horizontally and should be run at a speed of about 1200 R.P.M. The 
specimen should be kept cool on the grinding wheel by having water drip on it. 
Light pressure should be maintained on the specimen on all wheels or papers, 
whether for grinding or polishing. The edges of the specimen should be bev- 
elled where possible, in order to protect the cloth or paper from being cut. 
Specimens should be washed thoroughly in water after the grinding operation, 
in order to remove any trace of abrasives. There are two reasons for grinding 
specimens: first, to remove the marks of the saw or cutting disc, and in order 
to know when this has been accomplished it is wise to hold the specimen so 
that the grinding marks are at right angles to those already found on the surface 
to be prepared. The second reason for grinding is to have an absolutely flat 
surface. 

Rough Polishing. — This may be done with grade FF Turkish flour emery 
powder or French emery paper No. 1. The powder should be suspended in 
water and used on a smooth wheel of some sort covered with 12 ounce canvas 
duck. Very little powder and much water should be used, and again the speci- 
men should be turned 90 degrees so that the scratches produced by the powders 
or papers will be at right angles to those produced in grinding. The specimen 
should be washed thoroughly in water before passing to the next step, to remove 
all traces of abrasives. Some prefer to supplement the rough polish with 
French emery paper 0, 00 and 000. 

Fine Polishing. — Two or more steps are generally used. In the first step 
white reground tripoli powder or alundum powder No. 600 may be used in 
water suspension and placed on a wheel covered with a fine grade of broadcloth. 
The cloth should not be too thick or a relief polish will be obtained. Plenty 
of water and not too much powder should be used. 

The last operation may be performed with fine levigated alumina, grade 
No. 3, or with "superfine" magnesia powder. The best soft, high grade, 
jewelers' rouge powder may also be used. Levigated alumina or magnesia 
generally give better results than rouge, which is apt to scratch soft specimens. 
For this final operation "kitten's ear" silk broadcloth is preferable. When 
levigated alumina is used it should be suspended in water and squirted on the 
cloth disc by means of a devilbiss atomizer or any other type having a broad 
orifice. If magnesia is used it will harden and cake slightly unless the cloth 
is removed each time and kept soaked in a weak solution (2 per cent) of hydro- 
chloric acid (HCl) in distilled water. An exceptionally small amount of 
powder is necessary in the final polishing operation. 

Except where otherwise indicated, all suspended powders may be placed on 
the cloth covered disc by means of rubber set varnish brushes. Some prefer 
to wash off the powder from the cloth in the final polishing and polish for a 
few moments on the cloth alone, which is thoroughly wet with water. 

While the speed for grinding has been given as 1200 R.P.M. it is better to 
use lower speeds in the three other operations; namely, 300 to 600 R.P.M. 



218 APPENDIX A 

In every case specimens should be washed thoroughly after each stage of 
the operation. 

Especially soft metals, like lead alloys, must be ground and polished by 
hand throughout the entire operation. In grinding the soft specimens the 
specimens should be rubbed over the file and not have the file passed over them. 

Washing and Drying. — Specimens should be thoroughly washed in water 
after polishing and then washed in two baths of absolute alcohol and dried 
immediately by means of a blower. The best instrument for diying is some 
form of barbers' hair dry^er. Specimens should not be touched with the fingers 
after washing and drying or a greasy surface will be produced which will not 
etch evenly. Specimens should be carefully wrapped in cotton or placed in a 
desiccator until ready to etch and in the case of copper alloys etching and 
photography should be carried out as promptly as possible to avoid troubles 
due to tarnish. 

Refeeences 

Sauveur's Metallography and Heat Treatment of Iron and Steel, third 

edition, 1926. 
Guillet and Portevin Metallography and Macrography, second edition, 1922, 

Chapter 1. 
Goerens and Ibbotson, Introduction to Metallography, 1908, pages 121 to 130. 
C. H. Desch, third edition, 1922, Chapter VII. 
S. L. Hoyt, Metallography — Principles, 1920. 

W. Rosenhain, Introduction to the Study of Physical Metallurgy, 1914. 
C. 0. Burgess and J. R. Vilella, "Transactions," A. S. S. T., vol. 7, page 486, 

1925. 



o 

O 
»— I 

H 



pq w 






o 
o 

O 



o 

CO 

O 
»— • 

O 

CO 

O 

a 

u 



tr. 
t5 


These reagents are recommen- 
ded for etching to show Pearlite 
(both lamellar and granular), 
sorbite, ferrite and grain bound- 
aries in steels and irons (in- 
cluding cast iron). Nital brings 
out ferrite junction lines clearly 
wliile both Nital and Picral 
etch pearlite clearly. Carbides 
are unetched by these reagents. 


■*^ 

?^ 
+-' 

OJ 

CC 

UJ a! 




Only clear white nitric acid, 
1 42 sp. gr., should be used. 
In order to avoid tarnish 
troubles, specmiens, after etch- 
ing in either Nital or Picral, 
should be washed in at least 
two baths of methyl or ethyl 
alcohol (absolute) to remove 
the traces of acicl. Specimens 
should then be dried quickly, 
preferably with a clean air blast 
(cold or warm). Proposed by 
Boylston. 





cc 

ft 
p 


a 

a 




5 cc. nitric acid, cone, and 
95 cc. of either methyl or 
ethyl alcohol (absolute). 


1 cc. cone, nitric acid and 99 cc. 
of methyl or ethyl alcohol (ab- 
solute) . 


hC "3 


IS 

<a 
•C « 

c^ ft 

1—1 





a 


<a 


03 


■S 


fl 





2 


-§ 



§ 4 



13 


cc 





>, 


r/; 









^ 


'3 


,rt 


T3 





fl 


-tj 


c3 


W 


in 


£3 








-Q 




t4 


H 


c3 



aj 


c 




c3 


-7J 


ft 



< 



o .2S 5 



.-tS ft 



-a .a 

CI a; 

O <15 

Pi u 



•S >> 



OJ 


U2 


'^ 




-^^ 


n 


C5 




'^ 


01 


0) 




2 





H 







u 
(1) 


a 




a 







1 


^f 


a; 


-* 







u 


m 










m 


.^3 
-tj 




CO 


















Si 


2, 




bX) 


■n 


1 


-7; 


03 


O) 


CO 


A 


C3 

ft 


CLh 




43 


0) 




-tj 


dn 


,-i 


H 


M 


* 


^ 


-1— 


"^ 



219 



220 



APPENDIX B 



CO 




For hardened steels. May di- 
lute with 500 cc. of distilled 
water and use weak electric 
current. 


CO 

-a 

;h 
oj 
o 

o 

a 

(V 

B 

<v 
O 


E 


Sometimes better results are ob- 
tained by etching for a short 
time first in 5 per cent Nital and 
then in 5 per cent Picral. 


w 
s 

CO 

rn 

o 
o 

S-i 

a. 


Use boiling 5 to 10 minutes. 
Cementite colored. In tungs- 
ten steels, iron-tungstide (FcnW) 
and iron-tungsten carbide 
(Fe2W2C) are colored, but tung- 
sten carbide is unaffected. This 
reagent is most easily prepared 
by dissolving 25 grms. of 
NaOH in 60 to 70 cc. of water; 
add 2 grms. of picric acid and 
heat until dissolved; make up 
to 100 cc. with water. Keep 
at this volume. The mixture 
should always be alkaline as 
tested with litmus paper. Pro- 
posed by LeChatelier. 


_o 

'w 

a 

a 

o 
U 


Saturated solution (about 5 
grms.) picric acid in 100 cc. 
of methyl or ethyl alcohol 
(absolute). 


3 

'o 

2 . 

o " 

"8 


2 grms. picric acid; 25 grms. 
sodium hydroxide; water to 
make 100 cc. 


bt)% 


10;:^;^ 

is 

Ph a 


o 

o 
2 

CO 


1? 

o 

o 



APPENDIX B 



221 



CO 
cc 


Attacks and darkens iron-tung- 
stide in carbon free iron-tungsten 
alloys. When carbon is present 
this solution darkens the com- 
pound (FeW + WC?) in pro- 
portion to the amount of carbon 
present. 


Carbides and tungstides in 
tungsten and high speed steels. 
Structure of Stellite. 


to 

cc 

■J 

m 

Cm 

O 
« 

1 


3 

1 

CO 

03 

O 

^^ 


3 


Use fresh. Etch 10 to 12 min- 
utes. Tungsten carbide is dark- 
ened. Proposed by Yatsevitch. 


May be used cold or hot, but 
should be freshly made. Pro- 
posed by Murakami. 


Apply with a piece of cotton, 
rub gently, then wash with 
water and finally with alcohol. 
The time is lengthened by using 
a more dilute solution, allowing 
closer control of the depth of 
etching. The time is rarely over 
30 seconds. May be used elec- 
trolytically with very dilute solu- 
tions. Proposed by Curran. 




C3 

,o 

' -Ji 

o 
a 

2 
o 
O 


10 cc. hydrogen peroxide; 20 
cc. 10 per cent sodium hydrox- 
ide in water. 


10 grms. potassium ferricyanide; 
10 grms. potassium hydroxide; 
100 cc. water. 


10 grms. ferric chloride; 30 
cc. hydrochloric acid; 120 cc. 
water. 


5 grms. ferric chloride; 50 cc. 
hydrochloric acid; 100 cc. 
water. 


[VI Oj 


5. Hydrogen perox- 
ide and sodium 
hydroxide 


1 


7a. Ferric chloride 
and hydrochlo- 
ric acid 





222 



APPENDIX B 





1* 

02 
CC 

CO 
cc 

'o 

-1-3 
O 

;h 

m 




-^ 

OS 
53 


The mixture should stand 24 
hours before using. It is used 
full strength for rapid work, but 
requires very careful handling. 


Dissolve the salts in the least 
possible quantity of hot water 
and make up to 1000 cc. with 
alcohol. Cover specimen with a 
thin layer of the reagent and 
allow it to stand for 1 minute. 
Shake off the reagent and add a 
fresh layer, allow it to stand for 
1 minute more. Repeat as 
often as it is found desirable. 
Wash with boiling water and 
alcohol. Indicates presence of 
phosphorus segregations and 
yj progressive etching the differ- 
ence between the phosphorus 
in diff(M-ent portions of the 
same metal is shown. Pro- 
posed by Stead. 


a 

a 

o 
O 


§ 

•^ . 

ca § 
o o3 

2 o 

CO --H 


10 grms. cupric chloride; 40 
grms. magnesium chloride; 20 
cc. hydrochloric acid, cone; 
hot water, and alcohol to make 
1000 cc. 


IS s 


cS 

'So 

p:5 

a* 
<! 

GO 


.2t3 



APPENDIX B 



223 



o 
o 


o 
a; 

'o 

O 

■+-' 

CO 


'c3 

'o 

O 


OJ 
t» 

"3 

o 
p 

3 


Structure of medium and high 
carbon iron-chromium base al- 
loys and high speed steels; also 
high silicon iron alloys (in- 
cluding Duriron). 




/^ 
^^ 

o 

p* 


1 

to 


1 
1 

S -73 

Oi 3 

o -g 

M 


Warm the specimen in hot 
water before etching. For best 
results, use the method of alter- 
nate polishing and etching. 
May be used for iron-chromium 
base alloys containing Al, W, V, 
and Mo. Proposed by Vilella. 


.2 
o 


4 grms. copper sulphate; 20 
cc. hydrochloric acid; 20 cc. 
water. 


Saturated solution of ferric 
chloride in hydrochloric acid, 
to which a little nitric acid is 
added. 


100 parts hydrochloric acid; 
7 parts mercurous nitrate; 100 
parts water. 


1 part nitric acid; 2 parts 
hydrochloric acid; 3 parts gly- 
cerol. 


P^ 


1 

O 


a; 

fc!T3 

a; 3 


p 

si 

CO 


VI 

-73 S 
S 'bb 



224 



APPENDIX B 



o 



I ^ w p 



r^ 


■^ cc cc 


O 


t^ OS tu 




S-^ ? 


^ 


(^^ s 






c 


^ 3 rt 


§ 


O f5 " 




^ ^y. 




r2 O 


base 
iron-c 
Hadfi 


rr 




O. 


S.2 fl 


:3 


.2.t2 =^ 



O fa S ^_:; 

? g 1^ o 1^ 



GO U C3 CS r/3 



CD >> 

1^ Q 



OS 

Pi 



- O O 0) -■ ' .• 









c5 ?^ cS 



^ I I 

C3 0) r; o; 
-1^ -^^ .S 






T3 t» 



M OS O E"* ' 



~ bC. 
•3 OS 



PH 



'73-a o 
°^ o 



JH TSTS 



^ •- tH cS 



s 






1-0 

oS 






o P 



P^ a 

F^ '^ oS 

-.2^ o 

O > I 

lis 



i <i^ A 



00 ; 

, O) C Oi 

^ 3 ^-- 



os.-z; 



00-3 g 





li" 




"2 J -,; 




oS bC 




os bc-a 








a X 




'"^ M 




"^ cc 




-u 




-t^ Jh 




^^ 




^ ^ Oh 


,0 






ft 
^ bC 


l-D 


• - 




•s .^0 


in 




03-C5 




^-^-S 


a, 


'S 




« >^ 


£ 


_o oS 




.^ "^-^ 






■3 '^ 




■p t- cS 




-H 




^ a 




1;? 




1^-i^ 






3 


pa 
ydro 
erol; 




■-H rJ^ 





^< ^ 



^ 
^ 



APPENDIX B 



225 



o 

CO 

o 

CO 


1 

2 
-a 

o 

_bC 

a; 

M 


O 
rv 

i 

1.1 

xn CO 

II 

cc'a 




02 


On a 100 volt D. C. circuit use 
two 4 c. p. lamps in series 
connected with two wire ter- 
minals; preferably platinum 
wire. Flood the surface of the 
specimen with the solution. 
Make contact with one wire 
at side and dip the other in 
the solution, moving it around 
to obtain uniform etching. 


Wash salt well with distilled 
water to remove excess picric 
acid or alkali. Immerse in 
boiling solution for 20 min- 
utes. Iron phosphide attacked; 
cementite unattacked. Pro- 
posed by Matweieff. 


Use hot, freshly made solu- 
tion. Cementite is blackened, 
pearlite is turned brown, and 
massive nitrides remain un- 
changed. Proposed by Com- 
stock. 


c 

a 

a 

o 
O 


0.5 grms. sodium hydroxide; 
100 cc. water; low current 

density. 


c 
"o 

m 

1 
ft 

a 

-1-3 

3 


'to 

O 

g 

bC 




II 

WW 


a 


1 


to 
<a 
-a 

'S 

o3 

>^ 

s- 



226 



APPENDIX B 



l-H 
(Xl " 



o O 

t— I 

o ™ 

I— I 3 

I— I ^ 
H ft 

'-' >. 
o 

Q 
O 

w 

H 



d 




o 




a> 




bO 




03 




S 








-TS 




0) 




« 








c 


C 


M tu 1 


r^ 


OJ 


pl 


o 






O 
0) 


&4 

o 


2 


o 


a 








t3 


n 


e 


ji: 


03 








02 


^ 


o 


-M 




ja 


3 


bC 






<•) 




_g 


-fj 


01 


A 


> 


is 


s^ 




0) 


>-, 






OJ 


o3 


a3| 




O" 


o 


OJ 










r/) 


O 


<7S 






o 


O 
to 


o3 


_>. 


r^' 


3 




2 


CO 

03 


03 


bli 


o 






t3 
C 






f2 


2 

bC 



m .a :*^ 



Q 




a 


lU 




cd 


^ 




o 


o. 


1^ 


s 


s 

►^^w 


^3 
•S 
o 


-^s 


CO 


wo 


(U 


C/D HH 


C 




•J 


<A 




'o 


wr-' 


^ 


H^^j 


j3 


<Jrt 




Ont^ 


^ 


-Oh 




Q . 


C 


UP^ 


3 


fvlo 


" 


o 


o 

t-K 


o 


J3 
o 


o 


W 


s 




<; 




g 




o 







o 




A 


rfi 


o 
u 


S 


nJ 


O 


C 




.3 


CO 


•CJ 


I-) 




K> 






'C 








— ^i-° 


< 


o 


h-) 


iH 


PQ 


J3 










PJ 


& 


O 






U 


{H 


0) 
[A 


2 


o 
1-1 


o 


A 












H 





0) 


s 




. ^ 


UA 


•O-C 


^ 


0) 


o 


J«) 












<A'J1 
















< 


a 


OJ 




o 


0:1 




1— ( 


3 



-^-s 



^.23 
o ^ 






3 ?"J3 



Cti " in 






e3_-C 



W 



;h o3 ;-. . 
„ 03^ 3 i;- 



^ 9 

t s 

'^ CO 
O 4} 

re's 

M a 



C i i 



o fe 



M) 



o3 



II" 



o <u 

IS 

■-+3 ^.H 
o « <a 






03 n -^ 
C ^ S 



0) 



QJ 





^ 




II 


?5 






t-i 










0) 






-a -a 


S^ 


o 


c 


03 


3 
O 

a 


2 




i: 


03 

o3 


>^ 


o 


bO 


O 


is 


(3 


a; 


-r( 




H 




;m 


n 




hJ 


a 



O 03^— ^ 

S " c 

<^^ o3 






-r- O O 



t3 
CI 


1 
C 




03 






<U 


03 


















-3 




-' 


;h 




n 


O 






43 




O 


O 




■Ji 


03 

-1 




m 


O 




vO 


J3 




^^ 


01 




^1 


-i-j 










bCj3 






-(-> 
? 










^ 


bll 




ac 










^ 


-C 




3 


t) 




^ 






a 






3 


>. 


^ 


03 


-D 


o 




% 




>>-o 


o 


O O 




.^ 


r; 


>> 


(B 


o 


-DT3-0 



5-^ 

" 03 

b£ a 
«=3 

fc-. rr3 
O fC 

CO 03 

_, « bC 

03:3 •- -►^ 

.S e a — 
Oh H^ 

at. 



s -^ 



03 . e 

■o . o«.2 

C8> S 



C3 ^ 



S2 ^ 



^ d 



si 



13 

C 



•-^-i 




5^ fl^ 








1 ->j 




osX ^ 




>j « t< 




o3 >iH OJ 




& c 




-o .Is-TJ c 




2x 5-^ 




-S c*^-^*^ 




ISgJ^- 




<.S c"S- 




1'^ ^ § 




>- S^ . w 








c < — 




5! a; 


-i-> 


X -t? « — 


c 


-fe >r3 


c; 


^2:-s & 


^ 



APPENDIX B 



227 













i ^ (D t. 



a 

c . 
J o 

O 



■i^ S 3i fe c^ 



C! "S ^ 



^ 



WVJ \,\) Q 



3^ 
"0 43 





S 


1 




o 


1 






^ 


Cl 






-C 






^ 




§ 


>! 




T3 


o 

c 






S 

o 






o 

-2.S 


T3 

s 


"a? 
o 


Mi 


o 




1 

Oh 


'E 


-I-' 
r/1 


43 


<a 


OJ 


t> 






X! 


3 
q3 

S 

■a 




^ ^ 






^ — ^ 








o 




















^^-^ 








, , 






T3 


3 




0) 


O 






OJ 






3 




acr 




>. 


03 


-ri 


CO 


i^ 


o 


n 


O 


c3 


> 


(N 


o 




r\ 


u 






n 


^.rt 


3 




-t^ 


03 


o 


^ 


O 


44 

C5 


■p 


73 
43 


<f. 




O 


ti 


o 


rl 


03 




o 


t^ 


-C 


-IJ 


t— I 


w 


o 



Mo 





t*-. -^ 




w-3 




(U . 




+J QJ 




5? -s-o 




M <o O 


_> 


5 x-^ s 




<3^ o o 








(3 > p 
O OJ c 




t; b o 




t— 1 a O 




P^ 





rn 






a; 












ft 






'T3 






a) 






















T3 


a 


^—^ 


>- 










^ 


Ul 


OS 


o 


3 


O 


^ 


o 


T3 




> 


n 


<i 


0) 






a 


CO 




t<-i 


c 




^ 


§ 




OJ 


t4-l 




-I-' 


n 










o 












-. ^ 


rl 




m 


0) 



^ 


■i^ 




1 


o 

43 




>^ 












o3 


43 






O 
O 




0) 


a 


e 




<u 






o 


73 

a; 

43 
CO 




^ 


a 




R 


>>c 1 










'S 


+^ 








1— 1 


<u 


i-U 



o^ 


















-^^73 
















3-S 








« o3 






^ 3 


i^fl 






t3 O 






m'« 








-IJ 03 


45 O 






13 


o a 







OJ w 


o3 oJ 




o3 




So 
bo a 




G 




o3 CO 






3 
< 




gular f 
bright 


to 




C OJ 


OJ +s 




o3 '-=< 


:sg 




\0 to 


rn 


OJ 03"" 


If fine part 
3oHsh with 
lot work i 






Fairly larg 
ing change 
is changed 



43 


aj,~. 


CO 


-qTi 


3 


><.'^ 




42 


O «j 




C 0) 


CO 


3-iJ 


OJ 


•a =3 




3 OJ 




CS S:< 






03 


H ?. 


a 


3 




>-'-S 






Si 

03 


42 o;i 


o3 -e 

^43 


Sd 


23 


a 


Oh^ 


03 





1-2 





— 




,_^ 




c^l 




bC 


a 


3 


o 


CO 

03 


-o 


"^ 


3 


OJ 


rl 




^A? 






c 








^■^^ 



228 APPENDIX B 



References 



Sauveur, "Metallography and Heat Treatment of Iron and Steel," 1926. 

Hoyt, "Metallography," 1920. 

Goerens and Ibbotson, "Introduction to Metallography," 1908. 

Guillet and Portevin Taverner, "Metallography and Macrography," 1922, 

"Pamphlet No. 403," U. S. Bureau of Ordnance, Oct. 1916. 

"Circular No. 113," Bureau of Standards, 1922. 

Kerns, "Foundry Data Sheets," June 1 and 15, 1920. 

Groesbeck, Metallographic Etching Reagents, "Scientific paper No. 518," 
Bureau of Standards, 1925. 

Hudson, Etching Reagents and Their Application, "Journal," Institute of 
Metals, Vol. 13, page 193, 1915. 

Pilling, Microscopic Detection of Carbides in Ferrous Alloys, "Transactions," 
A. I. M. E., Vol. 70, page 254, 1924. 

Sauveur and Krivobok, Use of Sodium Picrate in Revealing Dendritic Segre- 
gation in Iron Alloys, "Transactions," A. I. M. E., Vol. 70, page 239, 1924. 

Vilella, Delving into Metal Structures, "Iron Age," Vol. 117, page 761, 1926. 



I 



APPENDIX C 

MICROSCOPES 

By W. L. Patterson* 

The use of the Microscope in Metallurgy differs somewhat from ordinary- 
uses in that the objects are opaque and must be illuminated from above gen- 
erally by means of a vertical illuminator. 

Any ordinary microscope may be used if proper objectives are available (see 
objectives). As the metal specimens vary in thickness they must either be 
mounted at a uniform height or the illuminating device must be attached to 
the vertical illuminator to move with it when focusing. 

The usual table or students microscope used for the examination of metal 
has an adjustable stage to provide for differences in thickness. 

In both of the forms described the specimens must be mounted with the 
polished side up and levelled so that the face of the specimen is perpendicular 
to the optical axis of the microscope. 

Where many specimens are to be examined and highest powers used as in 
research the inverted form of microscope is to be preferred. In this form the 
stage is above the optical parts and the specimen is placed upon the stage 
with the polished side down. 

Objectives 

The objectives (the lens nearest the specimen) are especially made for this 
work by being corrected for use without coverglass. This difference is scarcely 
noticeable on power of sixteen millimeter or less in focus but in the higher powers 
the definition is poor unless properly corrected objectives are used. , 

Objectives are made in a variety of focal lengths such as 48, 32, 16, 8, 4 and 2 
millimeters and their initial magnifying powers are 2, 4, 10, 20, 43 and 100 
respectively. By initial power is meant that the objective alone gives an 
image of certain magnification which in turn is again magnified by the eyepiece. 
We thus have the compound microscope. These initial magnifications vary 
in accordance with the distance between the eyepiece and the objective the 
greater the distance the greater the magnification. 

While this might seem a ready means of increasing or decreasing the mag- 
nification it does not prove successful in practice as the lenses are mathematically 
calculated to produce the best images at a particular distance. This distance 
is known as tube length and varies with different makers and on different types 

* Mr. Patterson of the Bausch and Lamb Optical Company, Rochester, New 
York, very kindly wrote this article at the author's request. 

229 



230 APPENDIX C 

of microscopes. The objectives are usually engraved with the tube length 
for which they are corrected and this distance is found by measuring the length 
of the tube from the shoulder against which the objectives screws to the shoulder 
against which the eyepiece rests. 

The resulting magnification is the product of the objective power and the 
eyepiece power. (See eyepieces.) 

These magnifications are based on the observation of a vertical image appear- 
ing at a distance of 250 millimeters in front of the eye, when looking into the 
microscope. They may be checked by projecting a real image at 250 mm. 
from the eyepiece. 

Eyepieces 

The eyepiece (lens nearest the eye) is used to magnify the image formed by 
the objective. Eyepieces are made in focal lengths of 50, 40, 33, 25, 20, 16 mm. 
with magnifications of 5, 6.4, 7.5, 16, 12.5 and 15 respectively. As stated 
under objectives it is the power of the objective multiplied by the power of 
the eyepiece, at correct tube length, which gives the total power of the micro- 
scope. Thus a 16 mm. focus objective of lOX with an eyepiece of 25 mm. 
focus of lOX gives at 160 mm. tube length a magnification of 100 diameters. 

Vertical Illuminators 

Vertical illuminators in common use are of two forms, the plane glass which 
covers the entire aperture of the objective and reflects light down through the 
objective to the specimen and at the same time permits the light to pass through 
it to the eyepiece and eye. This gives true central illumination and is preferred 
by many. 

The second form consists of a mirror or prism covering part of the objective 
aperture the light going to the specimen through one side of the objective and 
returning on the opposite side. This gives an angular illuinination and is 
useful in bringing out in relief parts of the specimen wliich may be above or 
below the principal surface. 

Illuminants 

lUuminants for metal examinations are usually the incandescent lamp or 
the arc lamp. The former is nearly always used in table work and may be 
used in photography although due to its less intensity longer exposures are 
required than with the arc. Only incandescent lamps with very compact 
filament should be used if good results are to be obtained. The ribbon form 
of filament is the best, other concentrated forms may be used but as the illumi- 
nant is usually focused upon the specimen the scattered filament gives an 
uneven illuinination. 

The arc lamp consists of two carbons automatically fed together as they 
consume and the light is taken from the crater of the upper carbon. Direct 
current should always be used with the arc lamp if available and if not available 
it is probably best to use the incandescent lamp. 



APPENDIX C 



231 



Cameras 

Any camera can be used to make a picture with the microscope but due to 
the necessity of soHdity, proper centering, etc., it is best to use a camera espe- 
cially made for photo-niicrographic work. 

The ultimate goal of every metallographer should be toward a complete 
outfit meeting all the requirements for the finest work. The illustration shows 
one of this type where all parts are built for this particular work. See Fig. 4. 



^^^^^^^^P 




•■(..'' ^S^^M 


^^^^BrT '" ' 






H 


■P^IBBB^^ 


^ffMmm 


Pi^^^BBl^H* 








i 


1 








^^Br^^l 




u 


B 



Fig. 4 



The microscope is of the inverted type. The holders for objectives and 
eyepieces are at a fixed distance (tube length) and solid. The specimen is 
inverted upon the stage and moved by mechanical means and due to the solidity 
of the stand the specimen may be of nearly any size and weight within reason. 
A focusing mechanism extends from the microscope to the ground glass at the 
rear of the camera. The illuminant, a 90 degree automatic arc lamp, and the 
condensers all firmly attached to the microscope to insure correct centering 
and separation at all times. The camera is solid and can be used for all mag- 
nification and sizes of plates. Shock absorbers are provided to guard against 
vibrations usually found in industrial laboratories. 



APPENDIX D 

PHOTOMICROGRAPHY* 

By Walter M. MixcHELLf and H. M. BoylstonJ 

The photomicrography of poHshed and etched specimens of metals with the 
aid of a microscope is important as a means of securing records of their micro- 
structure for reference and future examination. The production of such photo- 
graphs, called photomicrogra])hs (not microphotographs, which are merely 
photographs of microscopic size), requires proper care and skill in the manipu- 
lations, if satisfactory results are to be obtained. Before photomicrographic 
work is attempted, four things are essential: 

(a) The microscope and the source of illumination must be in proper adjust- 
ment, individually and with each other. 

(6) The microscope must be so mounted that it will be free from vibration. 
Ordinary vibrations are harmless if all parts of the apparatus are tightl}^ clamped 
together. 

Vibrations from steam hammers and from railroad trains passing close to 
the laboratory can be minimized by placing several inches of sponge rubber 
under the legs of the stand. If this does not correct the trouble the outfit 
may be suspended from the ceiling with spiral springs, or a spring suspen.sion 
stand may be used. 

(c) Specimens must be polished flat and free from scratches. 

(d) If the specimen is etched, the structure should be as clean cut as pos.sible. 
Lighter etching than that used in low power work is necessary for good results 
at high magnifications. 

Magnifications. — It is recommended that the following standard magnifica- 
tions be used in making photomicrographs (expressed in diameters): for 
ferrous materials, 10, 50, 100, 250, 500, 1000, 2000, 5000; for non-ferrous 
materials, 10, 25, 50, 75, 100, 150, 200, 250. 

The term photomacrograph is generally applied when the magnification is 
less than 10 diameters. In photomacrography the following magnifications 
are commonly used (expressed in diameters): |, 1, li, 2, 2?, 3, 5. 

Generally speaking, it is better to use a higher power objective rather than 
a lower for obtaining a given magnification if maximum resolution is desired, 
but too short a bellows length (projection distance) is also to be avoided. 

* Printed from the American Society for Steel Treating handbook, by permission. 
t Dr. Walter M. Mitchell is metallurgist. Central Alloy Steel Corp., Canton, Ohio, 
t H. M. Boylston is professor of metallurgy, Case School of Applied Science, 
Cleveland, Ohio. 

232 



APPENDIX D 



233 



Lenses. — In the following table are given the various lenses and lens com- 
binations which are convenient for obtaining different magnifications. 

Lenses for Various Magnifications 





Objective 




Ocular 


Linear 














Magnifi- 
cation 

in Diam- 
eters 


Type 


Focal 
Length 
(approx- 
imately) 
mm. 


Type* 


Ho 2 


Photographic Tessar lib 


153 


None 


2 to 10 


Photographic Micro-Tessar or 








Micro-Planar 


72 


None 


• 10 to 20 


Photographic Micro-Tessar or 








Micro-Planar 


48 


None 


20 to 30 


Photographic Micro-Tessar or 








Micro-Planar 


32 


None 


30 to 75 


Achromatic 


32 


Huyghens or similar 


75 to 150 


Achromatic 


16 


Huyghens or similar 


200 


Achromatic or Apochromatic 


8 


Compensating or 
projection eye- 
pieces for use with 






2 


apochromats 


200 to 500 


Achromatic or Apochromatic 




1000 to 5000 


Oil Immersion 









* The magnifying power of the ocular should be such that the desired size of 
projected image can be obtained with a moderate length of bellows. 

Determination of Magnification. — Where extreme accuracy is desired, 
magnifications should be measured experimentally with the aid of a stage 
micrometer. This is preferably made of metal and placed on the microscope 
stage in place of the specimen. The image of the rulings on the micrometer is 
then projected on the focusing screen and the magnification determined directly 
by means of a small scale, either ruled on the focusing screen or placed over it. 
Stage micrometers ruled to 0.1 and 0.01 mm. are the most convenient. The 
projection distance is the distance in millimeters or inches from outside focus 
of eyepiece lens to nearest (ground) surface of focusmg screen. Charts may 
readily be prepared for any combination of eyepiece and objective with the 
projection distance as one co-ordinate and magnification as the other. 

For approximate determination of magnifications which are sufficient for 
routine work the following formula may be used: 

M = eM.' 

260 



234 APPENDIX D 

where M is the magnification to be determined, D the projection distance 
measured in miUimeters, and M' the magnification of a particular combination 
of eyepiece and objective at 250 mm. (10 inches) projection distance. The 
values of M' are generally supplied by the manufacturer in a table accompanying 
the microscope, and may be given as the magnification at the eye, since the 
lens of the eye produces on the retina an image with a magnification corre- 
sponding to that obtained in projection at a distance of 250 mm. from the outer 
focus of the eyepiece. Since this outer focus of the eyepiece is very close (about 
3 mm. away) to the lens of the eyepiece the projection distance may be measured 
roughly by determining the distance from the eyepiece lens to the near side 
of the focusing screen. 

Illumination of Specimens, — For use with objectives of 32 mm. focal 
length or less, all of which are used in combination with oculars, vertical illu- 
mination (i.e., normal to the surface under observation) is usually necessarv. 
Either the plane-glass or mirror type of illuminator (the latter including the 
totally reflecting prism) in which the reflector is placed between the objective 
and the ocular may be used. For the best results, the condition of "critical 
illumination" should be obtained; that is, the optical distance from the source 
of light (real or apparent) to the surface of the specimen should equal the 
distance from the specimen to the focal plane of the ocular, or, in other words, 
the source of light should be approximately imaged on the specimen. The 
mirror or prism type of illuminator is not suitable for very short focus objec- 
tives (4 mm. or less), since it obscures a relatively large portion of the lens 
aperture. 

With objectives of the photographic type, vertical illumination is obtained 
by inserting the illuminator (plane-glass) between the lens and the surface of 
the specimen. Oblique illumination may be obtained by directing a beam of 
light so that it strikes the surface of the specimen obliquelj^ or, in a lesser degree, 
by rotating the reflector of the vertical illuminator. A special form of oblique 
illumination known as "conical illumination" and methods for obtaining it 
are described by H. S. George in the Transactions, A. S. S. T., Vol. IV, 1923, 
page 140. 

For lenses of the photographic type of more than 48 mm. focal length the 
illumination should be difl'used, for example, daylight, or oblique, as obtained 
by directing a beam of light upon the specimen obliquely from one side; or 
vertical, by means of a large plane-glass placed between the lens and the object. 
In order to increase the size of the field, which otherwise would be restricted 
in diameter to that of the photographic lens, a relatively large plano-convex 
lens should be placed between the reflecting plane-glass and the source of light, 
the lens being located so that the optical distance between it and the photo- 
graphic lens equals the focal length of the plano-convex lens. Moistening the 
surface of the specimen with water, glycerin or oil, or even immersing the entire 
specimen in alcohol or water, will often be found desirable for the purpose of 
increasing the contrast in the photograph. 

In the case of fractured specimens, a good reproduction of the fractured 



APPENDIX D 235 

surface may be readily obtained by using two sources of artificial light of unequal 
intensities. Place one source of light on each side of the specimen. A reflector 
may be used in place of the weaker light source if desired. The second, or 
weaker, illuminant serves to neutralize partially the deep shadows cast by the 
stronger one and so produces a good relief effect. 

Photographic Plates. — The most convenient size of plate or film for the 
average laboratory is 4 X 5 inch, but economy may be effected where a great 
many negatives are made daily by using a size 3i X 4i in h. Occasionally 
a 5 X 7 inch negative or even an 8 X 10 inch negative will be advantageous, 
especially in macrographic work. 

Various types of plates are listed below because of the difficulty in some 
localities of obtaining some preferable types. It is simpler and easier, however, 
to learn how to use one plate or film to the best advantage and stick to it. 
The Wratten M (panchromatic) plates have a special fine grained emulsion 
which gives a veiy desirable combination of detail and contrast. This detail 
and contrast may be varied according to requirements by the use of monochro- 
matic color screens. The Wratten filters, or screens, are as follows: B (green), 
F (red), K (yellow), etc. Nothing is gained by using these plates unless a 
monochromatic screen is used in conjunction with them. 

\\Tiile it is necessary, for the best results, to handle and develop Wratten M 
plates in complete darkness, the makers include in each box of plates a card 
giving the proper time of development for that particular emulsion. Allowance 
is made for low contrast, normal contrast, great contrast and varying tem- 
peratures of developer; thus an opportunity is afforded for the exercise of 
judgment on the part of the operator depending upon the conditions surround- 
ing the making of the negatives. There are other panchromatic plates but 
they do not give as good results. 

One of the disadvantages of panchromatic plates is their poor keeping quali- 
ties, especially in warm weather. 

The following brands of orthochromatic (isochromatic, i.e., sensitive to yellow 
light) plates may be used in conjunction with yellow or green screens with 
complete satisfaction, but they cannot be used with a red filter: 

Medium Speed: Standard Orthonon; Cramer Medium Iso; Stanley; 
Hammer Special Nonhalation Ortho. 

Slow Speed: Cramer Slow Iso; Hammer Slow Ortho. 

These plates are of average contrast, fine grained, and may be used for 
structures which show considerable contrast. 

Plates giving greater contrast but requiring slightly longer exposure are: 

Medium and Slow Speed: Cramer Commercial Isonon; Stanley Commer- 
cial; Hammer Commercial Ortho. 

Photographic Films. — The use of films for photomicrographic work has 
much to commend it. The cut films are easily handled in frames which hold 
them flat in the ordinary plate holder. Other frames of special non-corrodible 
material are available for holding the films in the developer tank and fixing 
box. Films do not crack or break during storage or shipment and take up 



236 APPENDIX D 

less space. They apparently stay flat during exposure since the negatives do 
not show "out of focus" areas. They are not yet available in the Wratten M 
emulsion but can be had in the Standard Orthonon type, and should be used 
in conjunction with a Wratten B or a K filter for the best results. 

Monochromatic Filters. — Since all photographic plates are most sensitive 
to blue light, for which the objective lenses are not corrected, and since the 
yellowish green rays are those most easily distinguished at the focusing screen, 
it is necessary to absorb the blue rays with a suitable color screen or filter. 
Through their use a good achromatic lens gives just as good or better results 
as an expensive apochromat. Moreover, apochromatic lenses always have a 
residual spherical aberration resulting in lack of flatness of field in spite of 
so-called compensating eyepieces. Most American achromats are corrected 
for the very color obtainable with a Wratten B (green) filter, so the latter is 
obviously the correct one to use in conjunction with a plate which is sensitive 
to green light, such as the Wratten M or the Standard Orthonon, Cramer Iso 
or Hammer Special Nonhalation Ortho. Some prefer a Wratten Ki, Ko or Ks 
filter, while others prefer the Wratten M plates and the Wratten B (green) 
screen. If the exposure is correct (and there is considerable latitude allowed) 
and the development correct, any gradation of detail and contrast may be 
obtained with this combination at low, medium or high magnification. The 
green color is also the most restful to the eye in visual work especially if a white 
ground screen is used in combination with it. 

Red screens (Wratten F) give more contrast and somewhat less detail than 
green (Wratten B) and are preferable in macrography where minute detail 
is less important than maximum contrast. 

Theoretically, it would seem as if a blue filter (short wave length) in con- 
junction with a proper plate would give better results where fine details are 
to be photographed at high magnification, but this does not appear to be borne 
out in the experiences of many of the most careful workers. Light of short 
wave length may have its advantages in the case of stained transparent objects 
using transmitted light, but it appears to offer no special advantage in metal- 
lography. 

For the best results the filter used should be kept in place while adjusting the 
final focus at the focusing screen. 

Some workers use a liquid filter such as a nickel chloride solution for green, 
or one of the green Aniline dyes, and for a yellow filter a saturated solution of 
potassium bichromate, but it is difficult to keep the solutions free from air 
bubbles and at the proper strength because of evaporation. A well made 
glass filter will last indefinitely if maintained at a point in the beam of light 
where the heat from the light is at a minimum. 

Exposure of Negative. — The time of exposure varies with the following 
factors : 

(a) Character of Specimen. — Bright or light colored structures, such as free 
ferrite or free cementite, require shorter exposures than dark ones like troostite, 
sorbite, pearlite, etc., and generally speaking, the darker the general appear- 



APPENDIX D 237 

ance of the structure and the less contrast it contains the longer will be the 
proper time of exposure. 

(b) Speed of Plate. — The faster the plate, the shorter will be the exposure 
required. 

(c) lutensitij of Light. — With a good carbon arc light and with iris dia- 
phragms and settings of the optical system arranged to give critical illumina- 
tion, the exposure required at 100 diameters magnification usmg direct current, 
a Wratten M plate and a Wratten B filter is approximately eight seconds. 
With alternating current under the same conditions the required exposure is 
twelve seconds. With a tungsten arc light which can be used only with direct 
current, and other conditions as stated, the required exposure is about forty-five 
seconds. With a 6 volt, 24 watt, automobile headlight type of Mazda incan- 
descent lamp the corresponding exposure would be about si.xty seconds. 

(d) Color of Light. — If the proper exposure with carbon arc and green 
(Wratten B) filter at 100 diameters is eight seconds, the exposure under similar 
conditions with a red (Wratten F) filter would be approximately six seconds 
for a Wratten M plate. For a yellow filter (K2) and other conditions the same 
as stated the exposure would be approximately four seconds. 

(e) Magnification Used. — If the exposure required at 100 diameters is eight 
seconds the exposure recjuired at 400 diameters would be approximately forty 
seconds or at 1000 diameters it would be approximately sixty seconds. 

(/) Size of Opening in Iris Diaphragms. — The size of the opening in the 
iris diaphragm between the source of light and the first condenser in most 
American instruments controls, to a considerable degree, the resolution of 
detail in the image; the smaller the opening the greater the resolution, but 
it is also true that the smaller the opening the longer the exposure. 

If the correct exposure time has not been obtained from the information 
given above then this should be determined by experience and trial. Adopt 
a system of making all exposures at standard magnifications of, say, 50X, 
lOOX, 500X, lOOOX, 2000X, 5000X. If this is done, after a little experience, 
the proper exposure time can be estimated by the appearance of the image 
on the focusing screen. The correct exposure time may be easily determined 
by exposing successive portions of a test plate to progressively longer exposures. 
Draw slide out of the plateholder so as to expose one inch of the plate, expose 
for 5 seconds, draw the slide out another inch, expose again for 5 seconds, and 
repeat until the whole plate is exposed. On developing, that strip which is 
correctly developed will indicate the proper exposure time. In any case the 
exposure should be sufficiently long so that the darker portions of the structure 
will be fully exposed; otherwise no details in these will be recorded and they 
will appear dead black in the final print. 

Plate Developers. — The safest and most convenient developer is generally 
that recommended by the plate or film manufacturer who is in a position to 
know what developer is best suited to the particular emulsion furnished. Direc- 
tions are generally given on a card or pamphlet found inside the box of plates 
or films. 



238 



APPENDIX D 



The developer recommended by the manufacturer of Wratten M plates is 
as follows: 

Pyro Soda DEVELOPf:R 

Developing Formula for Wratten and Wainwright M Plates 

Do not wet the film before applying developer 

Avoirdupois Metric 

A. Potassium Metabisulphite 250 grains 17 grams 

Sodium Sulphite (desiccated) 2| ozs. 70 grams 

Pyrogallic Acid f oz. 20 grams 

Water to 32 ozs. 1000 cc. 

Dissolve in order given. 

B. Sodium Carbonate (desiccated) 2f ozs. 75 grams 

Potassium Bromide 15 grains 1 gram 

Water to 32 ozs. 1000 cc. 

Use equal parts of "A" and "B." 

Typical Time of Development with above Formula in Minutes. 
Time varies somewhat with different batches of plates. 



Temperature 


Diminished 
Contrast 


Normal 
Contrast 


Great 
Contrast 


50 degrees Fahr. .... 


2.0 

1.0 

.5 


3.2 
1.6 

.8 


6.1 
3.2 
1.6 


65 degrees Fahr 

80 degrees Fahr 



Pyro developers are readily adapted to tank or time development and it is 
nearly impossible to overdevelop with them. 

For other plates and films the choice of a developer is largely a matter of 
personal preference. 

The two developer formuliE which follow, the result of many trials and 
experiments, are a normal developer for general work and a contrast developer, 
which will give maximum contrast, for contrast and lantern plates. They are 
recommended as having good keeping qualities, working rapidly, free from 
stain, and inexpensive to prepare. 

Make up a stock solution as follows: 

Normal Plate Developer 

Avoirdupois Metric 

A. Water (distilled) 32 ozs. 1000 cc. 

Sodium sulphite (desiccated) 1 oz. 30 grams 

Metal or Elon 60 grains 4 grams 

Hydrochinone 60 grains -1 grams 

Potassium bromide 30 grains 2 grams 

B. Water (distilled) 32 ozs. 1000 cc. 

Sodium carbonate (desiccated) f oz. 22 grams 



APPENDIX D 239 

Dissolve Elon before adding sodium sulphite; otherwise it may be reprecipi- 
tated: add other ingredients in order given. 
For a working strength developer, use equal parts of A, of B, and of water. 

Contrast Plate Developer 

Avoirdupois Metric 

A. Water (distilled) 32 ozs. 1000 cc. 

Sodium sulphite (desiccated) 2f ozs. 80 grams 

Hydrochinone -. § oz. 15 grams 

Potassium bromide i oz. 8 grams 

B. Water (distilled) 32 ozs. 1000 cc. 

Caustic potash If ozs. 48 grams 

For a working strength developer, use equal parts of A, of B, and of water. 
Ordinary' tap water may be used if free from iron salts. 

The stock solution will keep indefinitely if stored in well filled, tightly corked 
bottles. 

Either of the above developers in mixed solution inay be used until exhausted, 
5 ounces of the mixed solution being sufficient for one-half dozen 4x5 inch 
plates or their equivalent. Developer should be used at a temperature of 
65 degrees Fahr. This is very important, since higher temperatures will give 
failure due to "frilling" of the emulsion. At 65 degrees Fahr. development 
of a properly exposed plate will be complete in 3 to 5 minutes; longer time will 
increase the density of the negative, necessitating longer printing time, and 
increase the contrast. Insufficient development under above conditions indi- 
cates underexposure. 

After the plates are developed they should be rinsed thoroughly in water 
and fixed in the following fixing bath: 

Chrome Alum Fixing Bath 

Avoirdupois Metric 

Water 32 ozs. 1000 cc. 

Hypo 12 ozs. 350 grams 

When dissolved, add 1| ozs. (50 cc.) of the following hardening solution: 

Water 3^ ozs. 100 cc. 

Chrome alum 185 grains 12 grams 

Sodium bisulphite 308 grains 20 grams 

This bath ceases to harden the gelatine film after keeping for several days, 
so that in warm weather if the film tends to soften a fresh fixing bath should 
be prepared daily. 

In cold weather use one-half the quantity of hardening solution. If precipita- 
tion of dirty white and finely divided sulphur occurs, as sometimes happens 
while mixing or on long standing, it is better to throw the bath away and pre- 
pare a new one. Do not use old or discolored fixing baths. 

The following fixing bath, although it will not harden the gelatine film as 



240 APPENDIX D 

much as the chrome alum bath, maintains its hardening properties on keeping 
and is, therefore, preferable for use in hot weather. 

Fixing Bath for Hot Weather 

Avoirdupois Metric 

Water 64 ozs. 2000 cc. 

Hypo 16 ozs. 500 grams 

When dissolved, add the following hardening solution: 

Water 5 ozs. 150 cc. 

Alum (powdered) 1 oz. 28 grams 

Sodium sulphite (desiccated) 1 oz. 28 grams 

Glacial acetic acid 1 oz. 30 cc. 

When using the above solution, fixing will take about double the time (20 
minutes as a minimum) required to dissolve the unreduced silver emulsion, 
which is determined by noting when the grayish white color disappears from 
the back of the negative. After thoroughly fixing, negatives should be washed 
for one-half hour in running water to remove all traces of hypo, then stood 
on a drying rack so that they will drain from one corner. Films should be 
suspended from one corner to dry. 

A convenient test for determining whether washing is complete, which may 
also be used for prints, is made as follows: 

Test for Completion of Washing 

Avoirdupois Metric 

Water 8 ozs. 240 cc. 

Potassium permanganate 8 grains § gram 

Sodium carbonate 10 grains f gram 

Allow the excess water to drain from the partially washed negative or print 
into a graduate and add a few drops of the above solution. If the color remains 
pink, washing has been complete; but if it turns yellowish, hypo is still present. 
This is a verj^ sensitive test and is useful where speed is necessary. 

Over- and Under-Exposed Negatives, — Underexposed negatives will lack 
detail in parts corresponding to the darker regions of the specimen, while over- 
exposed will be "flat"; i.e., full of detail without much contrast. Whenever 
possible, it is better to repeat the exposure, making another negative giving 
double, or half the exposure time, as the case may be, than to attempt to 
"doctor" a poor negative. Nothing can be done with underexposure, as detail 
lacking in the negative originally cannot be introduced by any chemical process. 
Contrast may be increased in overexposed negatives, but the process is uncertain 
and the intensified negative is rarely permanent. Repeat the exposure, or 
use a contrasty paper when making prints. 

Overdeveloped negatives are very dense, requiring a long time in printing. 
These may be reduced in the following solution: 



APPENDIX D 241 

Reducing Solution 

Avoirdupois Metric 

A. Water 1 oz. 30 cc. 

Potassium ferricyanide 15 grains 1 gram 

B. Water 32 ozs. 1000 cc. 

Hypo 1 oz. 28 grams 

Mix A and B and immerse the plate in the solution until sufficiently reduced. 
Wash thoroughly and dry in the usual manner. The above solutions (A and B) 
keep well, but the reducer obtained by mixing A and B will remain active for 
only a short time. 

Printing. — Prints are made from the negative in the usual way. Use a 
constant light source and always place the printing frame at a constant distance 
from it (18 inches for a 100 watt bulb). The proper exposure for the print 
may easily be estimated from the density of the negative after a few trials. 
If many prints are to be made a special printing machine is a good investment. 

Satisfactory papers are Azo, Cyco, and Velox. Azo is somewhat slow to 
print but is cheap in price and easy to work with, and an excellent paper for 
general use. It is made in four grades, Nos. 1 to 4. The latter gives most 
contrast and is recommended for the average negative. Cyco prints more 
rapidly than Azo and is made in three grades: Contrast, Normal and Soft. 
The former is very contrasty, and the latter very soft and intended for very 
contrasty negatives. Normal Cyco is for general use and is about equivalent 
to No. 3 Azo. Velox is made in four grades in the same order as Azo. It is 
more expensive than Azo and has no advantage over it. It is to be remembered 
that "hard" or "contrasty" papers are to be used for "soft" or "flat" nega- 
tives, and vice versa. Always use paper with glossy surface. 

There is no single developer that will give the best results with all makes 
of papers. It is safe to use that recommended by the maker of the paper. 
For the above mentioned papers, the following may be relied upon to give good 
results. 

Make up a stock solution as follows: 

Dissolve in the order given: 

Avoirdupois Metric 

Warm water (distilled) 16 ozs. 500 cc. 

Sodium sulphite (desiccated) 1^ ozs. 35 grams 

Metal or Elon 30 grains 2 grams 

When completely dissolved, add: 

Hydrochionone 120 grains 8 grams 

Sodium carbonate (desiccated) If ozs. 50 grams 

Potassium Ijromide 15 grains 1 gram 

Sodium citrate 15 grains 1 gram 

Dissolve Elon in water before adding sodium sulphite; otherwise reprecipita- 
tion may occur. 



242 APPENDIX D 

This is a concentrated solution which will keep for months in filled, tightly 
corked bottles. For a working solution, dilute with 2 parts water for hard 
or contrasty papers or with 4 parts for normal and soft papers. Temperature 
of developer should be 65 degrees Fahr. 

Contrasty papers should develop quickly, 20 to 40 seconds, while soft and 
normal papers will develop more slowly, 40 to 60 seconds. The printing 
exposure should be so adjusted that development will be complete in the times 
specified. Too short exposure will require long development, giving cold, 
bluish tones; too long exposure will cause prints to flash up and darken before 
they can be removed from developer, giving muddy oUve tones. If altering 
the exposure time does not remedy this, the addition of a few grains of caustic 
potash or soda to the developer will remove olive tones, and a few drops of 
10 per cent solution of potassium bromide will correct blue tones. 

When prints are fixed in the fixing bath given above, 10 minutes are sufficient 
provided they are kept in motion. After fixing, wash in running water 30 
minutes, or until permanganate test shows absence of hypo. Dry prints on a 
ferrotype plate or " squeegee board " by placing them with surface down, covering 
with blotters and pressing into firm contact with a print roller. However, 
if the wash water is dirty or contains sediment, swab each print clean with a 
tuft of wet cotton before placing on ferrotype plate. When dry the prints 
may easily be stripped off, and will have a brilliant glossy surface which is 
very pleasing and which will show the finest details of the negative. Ferrotype 
plates should be kept clean and free from scratches. They may be washed 
with soap and water if necessary. Any tendency of prints to stick to the 
ferrotype plate may be overcome by rubbing its surface with a drop or two 
of three-in-one oil or paraffin dissolved in benzine, and polishing with a tuft 
of clean dry cotton or a soft cloth. 

Trimming of Prints. — This is most easily done with a knife edge print 
trimmer to a size 3| inches square or any other convenient size. Some prefer 
a circular shape and this can be done by cutting the dry print with a revolvuig 
print trimmer and a metal mask. Care must be used with tliis method to 
avoid rough edges on the print. Circular prints may also be made on square 
sheets during printing, by placing a mask made of red or black paper between 
the negative and the light. If the printing mask is used it should not be placed 
between the negative and the paper. In the latter position, fine detail may 
be destroyed. 

General Precautions. — Have a separate room set aside to be used for the 
dark room and for no other purpose. It should be provided with a wide bench 
along one wall with sink and running water at one end. A "safe fight "' over 
the sink and another at the other end of bench will be convenient, the latter 
for loading plate holders. Dust off plates with a soft camel's hair brush before 
loading, to prevent pinholes in the negative. Keep tilings in order, with a 
place for everything and everything in its place. Store negatives in paper 
envelopes with number, description and other data on each one, and with a 
catalog so that a given negative can be found quickly when wanted. Cleanli- 



APPENDIX D 243 

ness is essential. Do not allow dried developer to collect around necks of 
bottles. Have a special tray or hard rubber fixing box for the fixing bath and 
use it for no other purpose. Never use a hypo tray for developing. Rinse 
fingers and hands after handling prints in fixing bath before again using the 
developer. Hypo is an excellent thing in a fixing bath, but a very bad one in 
the developer. If developers or fixing bath get spilled, wipe them up and do 
not allow dried crystals to blow around the dark room. In warm weather put 
developing tray into a larger one containing ice water and thus keep solutions 
at their proper temperature. 

If possible printing should be, done in a separate dark room where an orange 
or dark yellow light will suffice. An electric fan is a great convenience for 
hastening the drying of negatives and prints. 

References 

Albert- Sauveur, "Metallography and Heat Treatment of Iron and Steel." 

1920, 2nd edition. 
F. F. Lucas, "High Power Photomicrography of Metallurgical Specimens," 

Transactions, American Society for Steel Treating, Vol. IV, 1923, page 611. 
H. S. George, "Conical Illumination in Metallography," Transactions, American 

Society for Steel Treating, Vol. IV, 1923, page 140. 
W. L. Patterson, "The Optics of IVIetallography," Transactions, American 

Society for Steel Treating, Vol. II, 1921, page 108. 
Recommended Practice for Photography as applied to Metallography, Com- 
mittee E-4, American Society for Testing Materials, Serial designation 

E7-23T, 1923. 
Eastman Kodak Company, "Photomicrograph}^," 5th edition, 1919. 
Walter M. Mitchell, "The Metallurgical Microscope," Forging and Heat 

Treating, Vol. IX, 1923, pages 63, 106. 



APPENDIX E(a) 



STANDARD DEFINITIONS OF TERMS RELATING TO 
METALLOGRAPHY* 

Serial Designation: E7-27 

Issued as Tentative, 1921; Adopted in Amended Form, 1924; Revised, 1927. 

Alloy. — A substance, having metallic properties, consisting of two or more 
metallic elements, or of metallic and non-metallic elements, which are miscible 
with each other when molten, and have not separated into distinct layers 
when solid. 

Note: Alloys when solid may be composed of eutectics, euteetoids, solid solu- 
tions, chemical compounds, or of aggregates of these components with each 
other or with pure metals. In the commercial sense, the term "alloy" would also 
include the case where some separation into distinct layers had occurred. 

Etching Reagent. — A substance or reagent used to reveal the structure 
of a metal or alloy causing a difference in the appearance of different constituent 
parts or different grains. 

Note: This substance is usually a solution of the reagent in water, acid or alkali, 
but etching may in some cases be brought out by a differential oxidation produced 
by ''heat tinting." 

Equiaxed Grain. — A grain which has approximately ecjual dimensions in 
all directions. 

Note: This term is practically restricted to unstrained metals. 

Grain. — A term used for an allotrimorphic ciystal present in metals and 
in one-component alloys. 

Note: Although a crystal may show division by "twinning," etc., it is regarded 
as the grain rather than smaller sub-divisions. In the case of alloys of more than 
one component, the crystal which, by its transformation, gave rise to these con- 
stituents is taken as the grain when its limits are still discernible; if the limits are 
not discernible the individual constituents are considered as grains. 

Grain Size. — This is preferably expressed as the number of grains per unit 
area of cross-section. The average cross-sectional area of the grain may also 
be given or the average dimensions. Grain size of strained material is expressed 

* Printed from the American Society for Testing Materials — Standards 1927, 
by permission. 

244 



APPENDIX E (a) 245 

by the average number per linear unit in Iwo directions, or bj^ the average 
number per unit cross-sectional area, together with the ratio of length to 
breadth (L/B). 

Note: By the "Intercept" Method for grain count, the number of grains and 
fractions of grains along a line of known length on two axes at right angles to each 
other are counted. By the "Planimetric'' Method for grain count, the number 
of grains and fractions of grains within a definite area are counted. 

Macrograph. — A graphic reproduction of any subject which has not been 
magnified more than 10 diameters. 

Note: When it is desired to indicate that it is a photographic reproduction, the 
term "photomacrograph" may be employed. 

Magnification. — The ratio of the size of the image to that of the object. 

Note: Magnification is generally expressed in "diameters," thus "XlOO" or 
" 100 diameters." 

Metal. — Any of the metallic elements, either of very high purity or of 
ordinary commercial grades. 

Note: Brass and many other alloys are metals in the commercial sense, but 
alloys in the scientific sen.se. 

Metallography. — That branch of science which relates to the constitution 
and structure, and their relation to the properties, of metals and alloys. 

Micrograph. — A graphic reproduction of any object magnified more than 
10 diameters. 

Note: When it is desired to indicate that it is a photographic reproduction, the 
term "photomicrograph" may be employed. 



APPENDIX E(b) 

DEFINITIONS OF OTHER METALLOGRAPHIC TERMS 

By Prop. H. M. Boylston* 

When specimens of iron and steel (and other metals and alloys) are suitably- 
polished and etched with dilute acids or other special reagents, certain char- 
acteristic crystalline formations are observable under the microscope. In 
most cases they correspond (in the case of iron and steel) to various fields on 
the iron-carbon equilibrium diagram, shown in Fig. 5. The following defini- 



1. 
Molten Iron 
(Fer Fondu) 




8.B. 
Cementite 

+ 
Pearlite 



2 3 

Carbon Per Cent 



Fig. 5. Iron-Carbon Diagram. 



tions of these constituents include their constitution, microstructure, occur- 
rence, and normal position in the iron-carbon diagram. 

Allotriomorphic Crystals. — When the free development of crystals is 
hindered by unfavorable crystallizing conditions, as, for example, contact with 
other crystals, likewise in process of formation, the regular external form is 

* Prof. Boylston has given the author permission to reproduce these definitions, 
published in the "Engineers," 1928. 

246 



APPENDIX E (b) 



247 



not preserved and the resulting imperfect crystals are called allotriomorphic 
crystals or occasionally "anhedrons" or faceless crystals. They are frequently 
called "crystaUine grains" or "grains" (Sauveur). 

AUotropy. — That property of certain substances by virtue of which their 
physical properties are suddenly and markedly changed at certain temperatures 
known as transformation temperatures, without a change in chemical com- 
position. Two allotropic forms of carbon are diamond and graphite. The 
allotropic forms of iron are thought to be alpha, beta, gamma, delta, although 
some doubt the existence of the beta form and some believe that the alpha and 
delta allotropic forms are identical. This term should not be confused with 
polymorphism, which is the property of some substances by virtue of which 
they crystallize in more than one form. Some use these terms a^ synonyms. 



1500 


L 










V 


^ 






y 


1300- 


\ 


\ 


\ 


-^ 


^^^ 


1100- 


A 






900- 


A 


/ 










B \^'^ 
C^Ar> 


■Jd 




Al-a.^. 




700- 
t;nn 


Ar^ 

1 ; 1 1 -J 1 



%c 



6.7 



Fig. 6. Equilibrium diagram of Iron-Carbon Alloys. Reproduced by per- 
mission from Sauveur's Metallography and Heat Treatment of Iron and Steel. 



>i Austenite is a solid solution of iron carbide, FesC (or of C?) in gamma iron. 
It occurs above GOSK in Fig. 5 {AHDF in Fig. 6) and probably in regions 
6 and 7 (Fig. 5). It is retained when cold in some high-carbon alloy steels 
and in some high-alloy iron-alloys, especially after rapid cooling. Under the 
microscope it appears as polyhedral grains. It has a face-centered space lattice. 

'\ Cementite is the definite carbide of iron (FeaC) and the hardest constituent. 
It contains 6.67% carbon. It occurs free in commercial plain carbon steels 
containing more than 0.85% carbon, and forms 12f% by weight of pearlite. 
It is normal in regions 3, 5, 8A and SB (Fig. 5). It appears as white, brilliant 
masses, networks, globules, or needles when free, or as the bright laminae in 
pearlite. Free cementite is also called "excess," "massive," "non-eutectoid," 
or "surplus" cementite, while the cementite included in pearlite is called 
''eutectoid cementite" or "pearlite-cementite." 



248 APPENDIX E (b) 

Crystals. — An arrangement of atoms forming small solids of regular 
geometrical outlines, such as cubes, octahedra, etc. (Sauveur.) 

Dendrites. — Crystalline groups or aggregates of allotriomorphic crystals 
arranged in distinct forms usually described as "tree-like," "fern-leaf," "pine- 
tree," etc. (Sauveur.) 

J Eutectic Alloy. — The word eutectic means "well melting." A eutectic 
alloy is that alloy in any series which has the lowest melting point of that series; 
the melting point is constant and occurs at a temperature known as the eutectic 
temperature. Eutectic alloys have a characteristic microstructure consisting 
of alternating laminations or a series of regular dots or rods occurring on a 
plain background. 

\ Eutectoid Steel. — Steel made up exclusively of pearlite or having such a 
content of carbon (0.90% in pure iron-carbon alloys, approximately 0.85% 
in commercial steels) that it would be made up exclusively of pearlite if slowly 
,cooled from above the critical range. 

\ Ferrite. — Ferrite is nearly pure iron. It may contain in solid solution 
such impurities as carbon (up to 0.05%), silicon (up to 4%), phosphorus (up to 
1.7%), nickel, copper, vanadium, molybdenum, tungsten and chromium in 
small amounts when in the alpha state. It is thought to exist in four allotropic 
forms: alpha, beta, gamma, and delta. Alpha iron is the softest constituent 
in iron and steel, and the principal one in ingot iron, wrought iron and low- 
carbon steel. It forms the dark lamina3 of pearlite of which it forms 87^%, 
by weight. It is found in regions 6, 7, 8A and 8B in Fig. 5. When free, 
alpha iron exists as polyhedral grains surrounded by dark networks. 
\ Graphite. — Graphite is carbon crystals seen in the form of curved or 
spiral plates in gray or mottled cast iron. It is also found in rounded masses 
or "rosettes" in malleable cast iron, and in this form also is thought to consist 
of minute carbon crystals. It is normal in regions 3, 5, 8A and 8B in Fig. 5 
when the alloys are very slowly cooled and especially if much silicon is present. 
It is also found in the rosette form, occasionally, in high-carbon tool steels, 
especially if the silicon be high (over 0.50%) or if there be any nickel present, 
in the absence of chromium. In such cases it is produced by annealing and 

\ ruins the steel. 
^ Hyper-eutectoid Steel. — Steel which contains more than 0.85% carbon 
and hence normally contains some free cementite after slow cooling from above 
the critical range. 
^ Hypo-eutectoid Steel. — Steel which contains less than 0.85% carbon 
and hence normally contains some free ferrite after slow cooling from above 
the critical range. 

Inclusions. — Solid non-metallic substances mechanically embedded in 
metals or alloys. 

Manganese sulphide (MnS) occurs in iron and steel containing more than 
a trace of sulphur. It appears under the microscope as round (in castings) 
or lenticular (in worked metal) dove-gray spots. 



/ 



APPENDIX^ E (b) 249 

Martensite (constitution disputed) is the principal constituent of hardened 
and untempered steels and is harder than austenite, troostite, or sorbite. 
Sauveur and others believe it to be an aggregate or mechanical mixture of a 
solid solution of carbon in supercooled gamma iron and of a supersaturated 
solution of carbon in alpha iron. Under the microscope it is seen as dark 
needles arranged indistinctly in equilateral triangles, and at very high mag- 
nifications, a still darker midrib of troostite (?) is distinguishable. 

Neximann Bands. — Mechanical twins appearing as a number of parallel 
lines or narrow bands which follow the orientation of the grains of metals. 
They are generally produced by sudden deformation of the metal such as 
(would result from shock, impact or explosion (Sauveur) . 

J Pearlite. — Pearlite is a mechanical mixture (aggregate) of alpha ferrite 
and cementite which is the principal constituent of slowly cooled annealed 
steels. It is always associated with an excess of ferrite or cementite except in 
steels containing between 0.70 and 0.90% carbon (theoretically 0.90% carbon 
in pure iron-carbon alloy and about 0.85% in commercial steels). It is normal 
in regions 8A and SB, Fig. 5. At low magnification it appears as dark irregular 
grains but at high magnifications it occurs as alternating curved, black and 
white lamellae. 

Solid Solution (as applied to metals) . — A mixture of metals or metalloids 
in the solid state in which the constituents are completely merged in indefinite 
proportions. 

Sorbite. — Sorbite is a transition stage between troostite and pearlite. 
It is believed by most authorities to be an uncoagulated conglomerate of irre- 
soluble pearlite with ferrite in hypo-eutectoid and cementite in hyper-eutectoid 
steels respectively. It is the principal constituent of air-cooled (normalized 
steels) and of hardened steels reheated to 1,112 to 1,292 degrees Fahr. (600 to 700 
degrees Cent.). It has no place in the diagram. It etches more rapidly than 
pearlite and at low magnifications appears as dark grains (darker than pearlite) 
surrounded by ferrite boundaries in hypo-eutectoid and by cementite boundaries 
or globules in hyper-eutectoid steels. In steels containing between 0.70 and 
0.90% carbon the structure is practically 100% sorbite after air-cooUng. At 
high magnifications, sorbite appears as a mass of mixed black and white dots. 
It is harder than pearlite but softer than troostite or martensite. 

Steadite. — The binary eutectic of iron and iron phosphide which occurs 
in gray cast iron. 

Troostite. — Troostite is generally believed to be an extremely fine aggre- 
gate of the carbide FesC and alpha iron. In the transformation of austenite 
it is the stage following martensite and preceding sorbite. By some it is con- 
sidered to be an uncoagulated conglomerate of the transition stages. It is 
colored decidedly darker than any other constituent by the ordinary etching 
reagents. It generally occurs as dark-colored irregular areas representing 
sections through nodules and is generally accompanied by martensite or sorbite 
or both. It may exist as membranes surrounding martensite grains. Sauveur 
believes it to exist as the midrib in needles of martensite. Sauveur has suggested 



250 APPENDIX E (b) 

that it may be a solid solution of iron and carbon, probably in the form of the 
carbide FesC in non-gamma iron. 

Twinning. — The grouping of two or more crystals or parts of a crystal 
in such a way that they are symmetrical to each other with respect to a plane 
between them (the twinning plane), which plane, however, is not a plane of 
symmetry (Sauveur). 



APPENDIX E(c) 

DEFINITIONS 

TENTATIVE DEFINITIONS OF TERMS RELATING TO 
HEAT TREATMENT OPERATIONS* 

(Especially as related to Ferrous Alloys) 

Foreword. — 1. During recent years certain confusion has arisen in regard 
to the meaning of commonly used heat treating terms. For instance, in one 
locaUty or trade any operation of heating and cooling, resulting in a softening 
of the material, is being called annealing, whereas in other places to "anneal" 
means not primarily "to soften" but to heat above the critical temperature 
and cool very slowly. Similar confusion as to meaning and application exists 
in regard to other terms and as a result "annealing," "tempering," "normaliz- 
ing," etc., are being used by different people to mean widely different things. 

2. In any attempt to accurately define the terms commonly used in connec- 
tion with heat treatment, the first question to decide and the most important 
one is: do the terms relate to the heat treatment operation itself, or to the 
results obtained by the treatment? In other words, is the term indicative of 
the structure or the condition obtained, or of the operation performed? 

3. After careful consideration, it appears most logical and most in keeping 
with present day usage to have the terms so defined that they shall mean 
definite operations and shall not be considered as referring to the resultant 
structures or general conditions. 

4. By "critical temperature range," as used in the definitions, is meant 
that temperature range illustrated by the diagram given in Fig. 7, taken from 
Howe. 

Definitions 

1. Heat Treatment. — An operation, or combination of operations, involv- 
ing the heating and cooling of a metal or an alloy in the solid state. 

Note: This is for the purpose of obtaining certain desirable conditions or prop- 
erties. Heating and cooling for the sole purpose of mechanical working are excluded 
from the meaning of this definition. 

2. Quenching. — Immersing to cool. 

Note: Immersion may be in liquids, gases or solids. 

* These definitions were prepared by a joint committee composed of representa- 
tives of the A. S. T. M., S. A. E., and A. S. S. T. Printed from the American Society 
for Steel Treating handbook, by permission. 

251 



252 



APPENDIX E (c) 



3. Hardening. — Heating and quenching certain iron base alloys from a 
temperature either within or above the critical temperature range. 

4. Annealing. — Annealing is a heating and cooling operation of a material 
in the solid state. 

Note {A): Annealing usually implies a relatively slow cooling. 
Note (B): Annealing is a comprehensive term. The purpose of such a heat 
treatment may be: 

(a) To remove gases. 

(b) To remove stresses. 

(c) To induce softness. 

(d) To alter ductility, toughness, electrical, magnetic or other physical properties. 

(e) To refine the crystalline structure. 





Acl 



Ac 3-2-1 



Fig. 8 



In annealing, the temperature of the operation and the rate of cooling depend 
upon the material being heat treated and the PURPOSE of the treatment. 

Certain specific heat treatments coming under the comprehensive term 
"annealing" are: 

A. Normalizing. — Heating iron base alloys above the critical temperature 
range followed by cooling to below that range in still air at ordinary temperature. 

Note: In the case of hyper-eutectoid steel, it is often desirable to heat above the 
Accm line, as shown in Fig. 8. 

B. Spheroidizing. — Prolonged heating of iron base alloys at a temperature 
in the neighborhood of, but generally slightly below, the critical temperature 
range, usually followed by relatively slow cooling. 

Note: (a) In the case of small objects of high carbon steels, the spheroidizing 
result is achieved more rapidly by prolonged heating to temperatures alternately 
within and slightly below the critical temperature range. 

(b) The object of this heat treatment is to produce a globular condition of the 
carbide. 

C. Tempering (also termed Drawing). — Reheating, after hardening to 
some temperature below the critical temperature range followed by anj^ rate 
of cooling. 

Note: (a) Although the terms "tempering" and "drawing" are practically 
synonymous as used in commercial practice, the term "tempering" is preferred. 



APPENDIX E (c) 253 

(6) Tempering, meaning the operation of hardening followed by reheating, is a 
usage which is illogical and confusing in the present state of the art of heat treating 
and should be discouraged. 

D. Malleablizing. — Malleablizing is a type of annealing operation with 
slow cooling whereby combined carbon in white cast iron is transformed to 
temper carbon and in some cases the carbon is entirely removed from the 
iron. 

Note: Temper carbon is free carbon in the form of rounded nodules made up of 
an aggregate of minute crystals. 

E. Graphitizing. — Graphitizing is a type of annealing of cast iron whereby 
some or all of the combined carbon is transformed to free or uncombined carbon. 

5. Carburizing (Cementation). — Adding carbon to iron-base alloys by 
heating the metal below its melting point in contact with carbonaceous material. 

Note: The term "carbonizing" used in this sense is undesirable and its use 
should be discouraged. 

6. Case-Hardening. — Carburizing and subsequent hardening by suitable 
heat treatment, all or part of the surface portions of a piece of iron-base alloy. 

Case. — That portion of a carburized iron-base alloy article in which the 
carbon content has been substantially increased. 

Core. — That portion of a carburized iron-base alloy article in which the 
carbon content has not been substantially increased. 

Note: The terms "case " and " core " refer to both case-hardening and carburizing. 

7. Cyaniding. — Surface hardening of an iron-base alloy article or portion 
of it by heating at a suitable temperature in contact with a cyanide salt, fol- 
lowed by quenching. 



d 



p( 



DUE DATE 


DEC ^ ^ !i' 

7 "^ 








> t i it 


[JUJ 




































































































































Printed 

in USA L 




t 



/ELLS BINDERY INC. 
FEB. i9o8 



TN 693.I7R37 



3 9358 00014057 1 



TN6 93 

17 

R37 



Reedy Everett Lenox* 

Photomicrographs of iron and steely 
by Everett L. Reed ••• with a foreword 
by Dr. Albert Sauveur ••• New York, J. 
Wiley S sonsT i nc • ; London, Chapman i> 
Hall, limited [cl&29] 

2 p. I., lil-xx, 253 p. illus«, 
diagrs. 24 cm» 



14057 



MPMU 



18 MAY 7 7 



168S280 NEDDbp 



i9-2112