Technical Note N-900 CORROSION OF MATERIALS IN HYDROSPACE - PART TI. IRONS, STEELS, CAST IRONS, AND STEEL PRODUCTS BY Fred M. Reinhart July 1967 Internal Working Paper "This document has been approved for public release and sale; its distribution is unlimited," NY f U. S. NAVAL CIVIL ENGINEERING LABORATORY Port Hueneme, California Tie Oe, VO. N GO , CORROSION OF MATERTALS IN HYDROSPACE - PART I. IRONS, STEELS, CAST IRONS, AND STEEL PRODUCTS Technical Note N-900 Y-F015=01-05-002A by Fred M. Reinhart ABSTRACT A total of 1300 specimens of 47 iron base alloys were exposed at depths of 2,340, 2,370, 5,300, 5,640 and 6,780 feet at two sites in the Pacific Ocean for 197, 402, 1064, 123, 751 and 403 days respectively to determine the effects of deep ocean environments on their corrosion behavior. Corrosion rates, pit depths, types of corrosion, changes in mechanical properties, effects of stress, and analyses of corrosion products are presented. The corrosion rates of all the alloys, both cast and wrought, decreased asymptotically with duration of exposure and became con- stant at rates varying between 0.5 and 1.0 mils per year after three years of exposure in sea water and partially embedded in the bottom sediments at a nominal depth of 5,500 feet. These corrosion rates are about one-third those at the surface in the Atlantic Ocean. At the 2,350 foot depth, the corrosion rates in sea water also decreased with duration of exposure but tended to increase sliehe ty with duration of exposure in the bottom sediments. The corrosion rates at the 2,350 foot depth were less than those at the 5,500 foot depth. The mechanical properties were unimpaired. Silicon and silicon-molybdenum cast irons were uncorroded. A sprayed 6 mil thick coating of aluminum protected steel for a minimum of three years and a hot dipped 4 mil thick coating of aluminum protected steel for a minimum of 13 months while a hot dipped 1.7 mil thick coating of zinc protected steel for about 4 months. The performance of metallic coated and uncoated wire ropes and cables is also discussed. Each transmittal of this document outside the agencies of the U. S. Government must have prior approval of the U. S. Naval Civil Engineering Laboratory. won une Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure 16. 70 18. LY) 3 FIGURES Area map showing STU sites off Pacific Coast; STU structure in inset. Oceanographic data at STU sites. Corrosion rates of low carbon steels at various locations. Corrosion rates of wrought iron and Armco iron. Corrosion rates of steels in sea water. Corrosion rates of steels in the bottom sediments. Statistical curves, 95 percent confidence limits, for steels in sea water. Statistical curves, 95 percent confidence limits, for steels in the bottom sediments. Median statistical curves for steels in sea water and in the bottom sediments. Effect of nickel on the corrosion rate of steel in sea water. Corrosion rates of cast irons in sea water. Corrosion rates of cast irons in the bottom sediments. Corrosion rates of austenitic cast irons in sea water. Corrosion rates of austenitic cast irons in the bottom sediment. Statistical curves, 95 percent confidence limits, of cast irons in sea water. Statistical curves, 95 percent confidence limits, of cast iroms in the bottom sediment. Statistical curves, 95 percent confidence limits, of austenitic cast irons in sea water. Statistical median curves for alloy steels, cast irons and austenitic cast irons in sea water. Statistical median curves for alloy steels, cast irons and austenitic cast irons in the bottom sediments. INTRODUCTION Recent interest in, and emphasis on the deep ocean as an operat- ing environment has created a need for information about the behavior of constructional materials in this environment. The Naval Facilities Engineering Command of the Office of Naval Materiel is charged with the responsibility for the construction of all fixed Naval facilities, including the construction and maintenance of Naval structures at depths in the oceans. Fundamental to the design, construction and operation of structures, and their related facilities, is information about the deterioration of materials in the deep ocean environments. This report is devoted to the effects of these environments on the corrosion of metals and alloys. A test site was considered to be suitable if the circulation, sedimentation, and bottom conditions were representative of open ocean conditions: (1) the bottom should be reasonably flat, (2) the site should be open and not located in an area of restricted circulation such as a silled basin, (3) the site should be reasonably close to Port Hueneme for ship operations, and (4) the site should be within the operating range cf the more precise navigation techniques. A site meeting these requirements was selected at a nominal depth of 6,000 feet. The location of this site in the Pacific Ocean in relation to Port Hueneme and the Channel Islands is shown in Figure 1 as Submersible Test Units (STUs) I-1, 1-2, 1-3, and 1-4. The environmental conditions at the bottom, a depth of 5,650 feet ata location about 5 miles northwest of STU I~l were reported to be as follows:* 1. Temperature 2 SINE 2. Salinity 34.58 ppt 3. Oxygen 1.29 m/l The com lete oceanographic data for Site I are shown graohically in Figure 2.°9" A portion of this data collected from 1961 to 1963 showed the presence of a minimum oxygen zone (as shown in Figure 2) at depths between 2,000 and 3,000 feet. Oceanographic data obtained at other Pacific Ocean sites also showed the presence of this minimum oxygen zone regardless of depth to the ocean floor. Corrosion rates are affected by the concentration of oxygen in the environment. Therefore, it was decided to establish a second expcesure site (STU Tl-! and TI-2) in the minimum oxygen zone at a nominal depth of 2,500 feet. nis site is aiso shown in Figure 1. A summary of the characteristics of the waters epproximately 1G feet above the bottom at the different exposure sites is giver i) Table: The NCEL oceanographic investigations aiso disclosed that the ocean floor at each of tnese sites was rather firm and was cnaracter- ized as sandy, green cohesive mud (partially glauconite) with some rocks. The biological cheracteristics of this sediment are described in References 4 through & The details of the construction, emplacement and retrieval of the STU structures are given in References 9 through 12. The procedures for the preparation of the specimens for exposure and for evaluating them after exposure are described in Reference 13. Previous reports pertaining to the performance of meterials in the deep ocean environments are given in References 13 through 17. This report presents and discusses the results obtained from ex- posure of irons, steels, Low alloy steels, alloy steels, unalloyed and alloyed cast irons, steel wire ropes, anchor chains ard me’ i coated products for six periods of time and at two nominal dep shown in Tebie i. 1 > rS RESULTS AND DISCUSSION The chemical composition of the irons, mild steels, high-strength low-alloy steels, alloy steels, high strength steels, nickel steels, alloy cast irons, austenitic cast irons, etc., are given in Table 2; their surface conditions ead heat treatments, if any, ere given in Table 3, Inciuded in Table 2 are the chemical compositions of the iron base alloys wnich were exposed on tne STU structures for che intex- national Nickel Company, Inc. Dr. T. P. May, Manager, Harbor Islend Corrosion Laboratory of the Internetional Nickel Company, Inc. has granted permission te incorporate his corcesicn deta (Reference 18), obtained from their specimens on the six STU structures, with tne NCEL data. Some additional data from another participant in the NcaL ex- posures, Aeronautical Materials Laboratory, are also included, (Refer- ences). Surface data of some alloys of chemicai compositions similar to those in Table 2 from the Atlantic Ocean (Reference 26} and similar to those from the Panama Cenai Zone, Pacific Ocean (Reference 21) are included for comparison purposes. Deep ocean data from the Atlantic Ocean is also included to permit comparison of the different deep ocean environments, References 22 - 24. The corresion rates and types of corrosion of all the metals are given in Table 4. In the column designated "Crevice"' an intentional crevice was created on one specimen of each alloy by bolting a i-inch square piece of the same alloy to the specimen with a nylon nut and bolt. The corrosion rates of some of the alloys are shown graphically in Figures 3 through 21. Water in the open sea is quite uniform in its composition through- out the oceans; therefore, the corrosion rates of steels exposed under similar conditions in clean sea water should be comparable. The results of many investigations on the corrosion of structural steels in surface sea water et many locations throughout the world show that after a short period of exposure the corrosion_rates are constant and amount to between 3 and 5 mils per year.“ °°’? Factors which may cause differences in corrosion rates outside these limits are variations in marine fouling, contamination of the sea water near the shorelines, variations in sea water velocity, and differences in the surface water temperature. IRONS AND STEELS Corrosion The corrosion rates of low carbon steels in sea water at different locations as indicated below are compared in Figure 3: a. Surface waters of the Atlantic Ocean at Harbor Island, North Carolina; b. Surface waters of the Pacific Ocean at Fort Amador, 9 Panama Canal Zone;21 9 9 c. Deep Atlantic Ocean waters, Tongue-of-the-Ocean, Bahamas 322923524 d. Deep Pacific Ocean waters, Port Hueneme, California. The corrosion rates of the steels at the surface in both the Atlantic and Pacific Oceans decrease rather rapidiy with time and become relatively constant after about 2 to 3 years of uninterrupted exposure. The higher corrosion rates at Fort Amador are attributed to the difference in temperature between the two sites (27°C vs 21°C). The corresion rates of the steels exposed at nominal depths of 5,500 and 2,350 feet in the Facific Ocean also decreased with time of exposure and were consistently lower than the surface corrosion rates. These lower corrosion rates are attributed to the combined effects of the differences between the variables at the surface and at the two depths; temperature, pressure and oxygen concentration. Also, the corrosien rates at a depth of 2,350 feet were lower than those at a depth of 5,500 feet. In this case, the lower corro- sion rates at a depth of 2,250 feet are attributed to the combined effects of the differences between the variables at the two depths; temperature, pressure aud oxygen cancentration, Table 1. Because of the interdependence of one variable on another, the above differences in tne corrosion rates cannot be attributed chiefly to any one variable. For example, the solubility of oxygen in sea water is increased as the pressure is increased at constant temperature but at constant pressure the solubility of oxygen decreases as the temperature increases, In their discussion of the effect of temperature, the inter- dependence of the effect of temperature and other rate factors on corrosion is discussed by LaQue and Copson state: 9 11y general, the effect of temperature on the corrosion rate depends on its influence on the factors controlling the corrosion reaction. Temperature may affect the corrosion rate through its effect on oxygen solubility and availability. As the temperature rises the oxygen colubility in an aqueous solution decreases. Opposed to this is the fact that the diffusion rate of oxygen increases with température. The corrosion rate of steel in aqueous saluticns with free access of air reaches a maximum at about 175°F. On the ether hand, in a closed system where the pressure was allowed to increase, the corrosion rate in- creased linearly at ebout 3 percent per degree which suggests control by the diffusion rate of exygen te the steel. Temperature may affect eorrosion through its effect on pH. The dissociation ef water in- ereases with temperature with the result that the pH decreases with temperature (becomes more acid). Temperature may also affect corro- sion rate through its effect on films. [It may increase the solubility of corrosion products im seme cases in other cases cause the pre~ cipitation of protective films and in srill other situations change the characteristics of corrssion products to render them more imper- vious to oxygen diffusior.” According to H. H. Uhlig: 72 "When corrosion is controlled by diffusion of oxygen, the corrosion rate, at a given oxygen concentration, approximately doubles for every 30°C rise in temperature." However, jaQue3l has pointed out that in flowing sea water, when no fouling organisms become attached to smali, fully immersed specimens, corrosion of steel at 11,.1°C proceeded at 7 MPY compared with 14 MPY at 21.1°C. This increase (twofold) corresponds with what would be expected from chemical kinetics, where the rate of reaction is approximately doubled for a rise of 10°C. Uhlig-’ has shown that the corrosion rate of iron in air saturat- ed water is proportional to the oxygen concentration. He has also conducted experiments in the laboratory which show that at constant temperature the corrosion rate of steel in a calcium chloride solution increases in direct proportion to increase in oxygen concentration. When steel is in free contact with sea water its corrosion rate increases as the velocity of the water increases .2/ Within the range of about pH 4 to 10, the corrosion rate of steel in aerated water at room temperature is independent of pH, and depends only on how rapidly oxygen diffuses to the metal surface. ig “Ig SEiee@alte states; "It is a remarkable and important fact that except where there is gross dilution or contamination, the relative proportions of the major constituents of sea water are practically constant all over the world."' “In the major oceans the salinity of sea water does not vary widely, lying in general between 33 and 37 parts per thousand; 35 parts per thousand is comaonly taken as the average for "“open-sea" water.'' Nevertheless, the corro- sion rates at a depth of 5,500 feet in the Pacific Ocean were about one-third the rate of the steels at Harbor Island after about 3 years of exposure, Variables which were different between the surface in the Atlantic Ocean at Harbor island, North Carolina, and at a depth of 5,500 feet in the Pacific Ocean are given in Table 5. The current at the surface was variable in direction and magnitude, being due only to normal tidal action; at depth in the Pacific Ocean there was practically no current; hence, there was probably very little effect due to differences in current alone. As discussed above, the dif- ference in pH between the two sites would be expected to be ineffectual. Hence, the difference in corrosion rates is attributed to differences in pressure, temperature and oxygen concentration. The corrosion rates for a steel exposed by the Naval Research Laboratory at a depth of 5,600 feet in the Tongue-of-the-Ocean in the Atlantic were slightly higher than those in this investigation, Figure 3, Oceanographic data reported for the Tongue-of-the-Ocean are; depth, 4,967 feet; 4.18°C and 5.73 ml/1 oxygen. Since the differences between the depths, pressures and temperatures are small the higher corrosion rates in the Atlentic are attributed chiefly to the difference in the concentration of oxygen between the two 30 lecations (5.73 vs 1.4 ml/1} with the possibility that some of the corrosion might be due to the difference in the currents (unknown in the Atlantic but practically stagnant in the Pacific}. The difference between the corrosion rates on the surface at Harbor Isiand, N. C. and at 3 depth of 5,600 feet in TOTO is attributed to dif- ferences in depth (pressure, 0 vs 2520 psi) and temperature (19°C vs 4,22). Corrosion rates for steel at a depth ef about 4,500 feet23524 in TOTO were practically the same as those at the surface at Harbor Island for comparable periods of time. The corrosion rates of wrought iron and Armee iron at depths were comparable with those of ALS? 1010 steel 4s shown in Figure 4. The cerrosion rate of wrought iron at the surface at Fort Amador in the Pacific Ocean Panama Canal Zone*? after about 3 years of exposure was approximately 7 times greater than at a depth of 5,500 feet in the Pacific Ocean. The corrosion rates of ail the alloy steeis at depths of 5,500 and 2,350 feet in sea water are shown in Figure 5. These values are shown as shaded areas encompassing most of the vaiues. The corrosion rates for these steels decreased similarly to those for carbon steel with time of exposure at botn depths. Although the corrosion rates at a depth of 5,500 feet varied batween 1.9 and 6.0 MPY after 123 days of exposure they were all essentially the same 2frer 1,064 days of exposure (0.5 to 0.9 MPY). The performance of these same steels when partially embedded in the bottom sediments is shown in Figure 6. After 1,064 days of exposure at a depth of 5,500 feet, the corrosion rates were the same as those in the sea water above the bettom sedi- ments. However, the corrosion rates for many cf the steels after 403 days of exposure in the bottom sediment at a depth of 6,/80 feet were less than 0.5 MPY; this is attributed to the greater proportion of each specimen that was embedded in the bottom sediment. ‘The specimens of these particular steels were about 2 inch diameter discs and in all probability were nearly completely embedded in the bottom sediment. The data for all the steels was analyzed statistically. The mean curve of the corresien rates and 95 percent confiderce limits area shown in Figure 7 for the specimens exposed in the sea water and in Figure 8 for the specimens partially embedded in the bottom sediments. The corrosion rate curves for ATST 1010 steel end high-strength-low alloy steel #2 exposed at 3 depth ot 5,600 feet in TOTO ars also included to reveal that they are outside the 95 percent confidence limits. The fact that they are outside the 95 percent confidence limits of the corrosion rates of the steels exposed at a depth of 5,500 feet in the Pacific Ocean indicates that the environment in the Atlantic Ocean is somewhat different from the environment in the Pacific Ocean. The median curve of corrosion rates for the 2,350 foot depth is below that for the 5,500 foot depth indicating a dif- ference in environments even though the confidence limits overlap. In the case of the median corrosion rates curves for the specimens in the bottom sediments (Figure 8), the median vaiues are the same after 400 days of exposure indicating that the environments are nearly identical. The median corrosion rate curves for the 2,350 foot and 5,500 foot depths are shown in Figure 9. Between 200 and 400 days of exposure the corrosiveness of the bottom sediment at 5,500 feet was the same as the sea water at the 2,350 foot depth. After 400 days of exposure the bottom sediments at the 5,500 foot and 2,350 foot depths and the sea water at the 2,350 foot depth were of equal aggressiveness. After 751 days of exposure at the 5,500 foot depth, the sea water and bottom sediment environments were similar with regard to their effect on the corrosion of steels. Since no data are available for the 2,350 foot depth for periods of exposure beyond 400 days it is not possible to correlate the corrosion of steels at the two depths beyond this duration of exposure. Variations of from 1.5 to 9 percent in the nickel content of steel were ineffectual with respect to the corrosion rates as shown in Figure 10. The corrosion rates of AISI Type 502 steel (54 Cr=-0.5% Mo) were erratic and higher than for the other steels. This behavior is attri- buted to the broad shallow pitting and severe crevice corrosion at insulators and fasteners. The corrosion rate for a nickel=cobalt high strength (190 KSI) alloy steel was within the limits shown for other alloy steels in Figure 5 for 402 days of exposure at a depth of 2,370 feet. Specimens of two heats of 18% Ni maraging steels from NCEL and one heat from INCO were exposed for 402 days at a depth of 2,370 feet. The 0.08 inch thick material from one NCEL heat was aged at 900°F for three hours and air cooled, then a portion was welded. This material, both unwelded and welded corroded at twice the rate of the material from the other heats, 3.2 MPY vs 1.4 MPY. The material aged by NCEL had a yield strength of 315 KSI while the yield strengths of the heats aged by the producer were in the range of 235 to 265 KSI. The corrosion was uniform with tightly adhering films of black corrosion products. The data in the column labeled "Crevice" in Table 4 show that there were no significant changes in the corrosion rates of these alloys due to crevice corrosion. Although crevice corrosion is reported in some cases, the intensity and amount was not great enough to significantly change the corrosion rate of that particular alloy. Stress Corrosion Some of the steels were exposed in the stressed condition at values equivalent to 35, 50 and 75 percent of their respective yield strengths. The steels, stresses, depths, days of exposure and the susceptibility to stress corrosion cracking are given in Table 6. None of these steels were susceptible to stress corrosion cracking for the periods of time exposed at the various depths. Mechanical Properties The percent changes in the mechanical properties of the exposed steels are given in Table 7. There were no significant changes in the mechanical properties due to corrosion except for the AISI Type 502 steel, The decreases in elongation, 34-38 percent, of the AISI Type 502 steel were considered significant and were attributed to the pitting corrosion. Corrosion Products The corrosion products from some of the steels were analyzed by X-ray diffraction, spectrographic analysis, quantitative chemical analysis and infrared spectrophotometry. The constituents found were: Alpha iron oxide = Fe 03 ° H50 Iron hydroxide = Fe(0H)9 Beta iron (III) oxide hydroxide ~ Fe00OH Tony oxideshydrates = hcp 0 nn. H,0 Significant amounts of chloride, sulphate and phosphate ions. Anchor Chains Two types of 3/4 inch anchor chain, Dilok and welded stud link, were exposed at the depths and for the periods of time shown in Table 1. The chain links were covered with layers of loose, flaky rust after each exposure. The layers varied from thin to thick as the time of exposure increased. Destructive testing of the exposed chain links (Table 8) showed no decrease in the breaking loads of the links for periods of exposure of at least 1,064 days. Hence, there was no impairment of the strength of either of the chains. The Dilok links all failed at the bottoms of the sockets where the cross-sectional area of the steel was the smallest. Rust was present in all these broken sockets indicating that sea water had penetrated the joints. Stagnant sea water in these sockets for prolonged periods of time could result in destruction of the links due to the internal stresses created by the formation of corrosion products. Wire Rope A number of metallic wire ropes were exposed at various depths and for different periods of time as shown in Table 9. These were plow steel, galvanized steel, aluminized steel, stainless steel and 90 copper-10 nickel clad stainless steel ropes and cables of different types of construction. The first three ropes in Table 9 were for an evaluation of the effect of plastic tape on the corrosion and strength of a conventional wire rope. The breaking strengths were the same after exposure and were in agreement with published nominal values for this type of rope. There was more rust on the inside strands of the degreased rope than on the one in the "as received" (lubricated) condition. For a dis- tance of about 3 feet from the eyes there was considerably more rust underneath the polyethylene tape, than on the degreased rope. About 50 percent of the inside strands were rusted at the break in the rope. This test indicates that no corrosion protection is afforded by taping when sea water has access to the interface between the rope and the tape. The zinc on the 0.125 inch diameter, 7 x 19 construction, lubri- cated galvanized aircraft cable was completely covered with red rust after 403 days of exposure at a depth of 6,780 feet. In addition, the breaking strength had decreased by 50 percent. The amount of zinc remaining on the other five galvanized ropes varied from none in the case of the 0.094 inch diameter, 7 x 7 cable which was 100 percent rusted on the outer surfaces to considerable remaining on the 0.25 inch diameter, 7 x 19 construction cable which was dark gray. There was no loss in the breaking strength of any of these five cables. After 403 days of exposure at a depth of 6,780 feet the smaller diameter (0.094, 0.125 and ©.187 inch diameter) stainless steel cables lost considerable strength, 90, 86, and 96 percent respectively. These decreases were all attributed to crevice corrosion of the internal wires. Many pits were also found on the individual wires away from the breaks and some broken ends were protruding from the cables prior to testing, There was no loss in breaking strength of the three larger diameter stainless steel cables, the inside strands were chiefly metallic color with only a few localized rust spots. Two types 304 stainless steel cables clad with a 90 percent copper-10 nickel alloy were exposed for 402 days at a depth of 2,370 feet. One cable, 1 x 37 x 7 construction with a 0.3 mil thick clad layer was covered with rust on the outside but the inside wires were uncorroded, The other cable, 7 x 7 construction with a clad layer 0.7 mil thick was covered with green corrosion products on the outside, uncorroded on the inside strands and had lost no strength. Three aluminized steel cables (7 x 7, 1 x 19 and 1 x 19 construc- tion) with 0.6, 0.6 and 0.7 mil thick coatings lost no strength during the 402 day exposure at a depth of 2,370 feet. The 7 x 7, 0.187 inch diameter cable was covered with white corrosion products and a few light rust stains but the inside strands were dull gray in color. The outside surfaces of the 1 x 19 construction wires (0.250 and 0.313 inch diameter) were gray in color with scattered white corrosion products covering about 50 percent of the surfaces. The inside strands were a dull gray color. Eight wire ropes were stressed in tension equivalent to approxi- mately 20 percent of their respective original breaking strengths as shown in Table 10. There were no stress corrosion failures after either 751 or 1,064 days of exposure. However, the breaking strength of the Type 316 wire rope lost 40 percent of its strength after 1,064 days of exposure at a depth of 5,300 feet because of crevice corro- sion of the internal wires. The breaking strength of the galvanized plow steel (0.83 oz Zn) was decreased by 17 percent. The breaking strengths of the other six wire ropes were unaffected. Although there was no loss in the breaking strength of the 18 percent chromium-14 percent manganese stainless steel rope there were quite a number of broken wires due to corrosion both on the outside and on the inside strands. 10 Metallic Coatings Zinc, aluminum, sprayed aluminum and titanium=cadmium coated steel specimens were exposed at depth. The galvanized steel (1.0 oz per sq ft) was covered with a layer of flaky red rust after 402 days of exposure at a depth of 2,370 feet. The corrosion rates were 0.9 MPY for the specimens exposed in the sea water and 0.4 MPY for the specimens partially embedded in the bottom sediment. The corrosion rate for bare steel (AISI 1010) in sea water under the same conditions was 1.2 MPY indicating that the zinc coat- ing was removed within a short period of time (3 to 4 months). The difference in corrosion rates in the bottom sediment was 0.7/7 MPY which shows that the zinc coating protected the steel in the bottom sediment for at least twice as long as it did in the sea water. There was no loss in the mechanical properties of the galvanized steel, The aluminized steel (1.03 oz per sq ft) was covered with white corrosion products, spotted with a few specks of red rust after 402 days of exposure at a depth of 2,370 feet. About 22 percent of the aluminum coating was corroded from the specimens exposed in the sea water and 40 percent was corroded from the specimens partially embedded in the bottom sediment; the underlying steel had not corroded. Therefore, it can be concluded, on a weight basis, that 1 oz per sq £t of aluminum will protect steel for a longer period of time than 1 oz per sq ft of zinc; about 4 times as long in sea water and about 2 times as long when partially embedded in the bottom sediment. A titanium=-cadmium coating on AISI 4130 steel was completely sacrificed and the steel was covered with a layer of red rust after 402 days of exposure at a depth of 2,370 feet. A 6 mil thick, sprayed aluminum coating which had been primed and sprayed with 2 coats of clear vinyl sealer protected the under- lying steel for 1,064 days of exposure at a depth of 5,300 feet. After removal from exposure the aluminum coating was dark gray in color, speckled with pin point size areas of white corrosion products. Cast Irons The chemical compositions of the cast irons are given in Table 1 and their corrosion rates in Table 4. The corrosion rates for the gray, nickel, nickel-chromium, silicon, silicon-molybdenum and ductile cast irons at the two nominal depths in the Pacific Ocean are shown graphically in Figure 11 for sea water and in Figure 12 for the bottom sediments. There was no measurable corrosion of the silicon and silicon- molybdenum cast irons at either depth. In sea water at both depths the other cast irons behaved similarly to the steels as is clearly shown by comparing the curves in Figure 5 with those in Figure 11. This similarity also obtains for the specimens partially embedded in the bottom sediment at the 5,500 foot depth; compare Figure 6 with Figure 12, At the 2,350 foot depth there is an anomaly in that the corrosion rates of the cast irons increase with time (Figure 12) whereas those of the steels tend to be constant with time. The reason for this increase is not apparent at this time. The corrosion rates of the austenitic cast irons in sea water are shown graphically in Figure 13 and in the bottom sediment in Figure 14. The corrosion rates of these alloys in sea water also decrease with time of exposure at both depths with the rates at 2,350 feet being lower than those at 5,500 feet. However, such was not the case in the bottom sediments. For some presently in- explainable reason the corrosion rates after 400 days of exposure at a depth of 6,780 feet were much lower than after 750 days of exposure at a depth of 5,640 feet as well as slightly lower than after 1,064 days of exposure at a depth of 5,300 feet. This is the only group of alloys which behaved in this manner. At a depth of 2,350 feet the average corrosion rates were about the same for both periods of exposure and, again, were lower than for the other groups of alloys except the cast irons after 200 days of exposure (Figure 12). The statistical curves and the 95 percent confidence limits for the two groups of cast irons both in the water and the bottom sediments are shown in Figures 15, 16 and 17. Very few values were outside the 95 percent confidence limits; one value after 1,064 days of exposure in the bottom sediment at 5,500 feet, one value after 197 days of exposure in the sea water at 2,350 feet, one after 400 days of exposure in the bottom sediment at 5,500 feet and ome after 400 days of exposure in the bottom sediment at 2,350 feet. Mechanical Properties The percent changes in the mechanical properties of the exposed cast irons are given in Table 7. The mechanical properties of Ni- Resist No. 4 were not affected but those of Ni-Resist D-2c were significantly lowered. 12 About 80 percent of the surfaces of fracture of each broken tensile specimen was black in color and the other 20 percent was gray, in contrast to entirely gray surfaces of fracture for unex- posed specimens. Metallographic examinations of surfaces normal to and at the edge of fracture showed that selective corrosion of an intermetallic constituent had occurred which caused the reduction in the mechanical properties. The median curves for the two groups of cast irons and the alloy steels are shown in Figure 18 for sea water and in Figure 19 for bottom sediments. These curves (Figure 18) show that in sea water at a depth of 5,500 feet corrosion behavicr of these three groups of alleys was the same after 750 days of exposure. There was a slight decrease in the corrosion rates of the three groups of alloys with time at a depth of 2,350 feet and the corrosion rate of each group was lower than that of its companion group at a depth of 5,500 feet. In the bottom sediments the behavior of the alloys was somewhat erratic. The lower corrosion rates after 400 days at a depth of 6,780 feet is attributed to the fact that a greater pro- portion of each specimen was embedded in the bottom sediment than during the other three exposure periods at the nominal depth of 5,500 feet. The corrosion rates at 2,350 feet tended to increase slightly with time for the steels and austenitic cast irons while those for the cast irons increased sharply. The type of behavior for the cast and wrought alloys can only be attributed to their proximity to the water-sediment interface or the percent embedment in the bottom sedi- ment. SUMMARY AND CONCLUSIONS The purpose of this investigation was to determine the effects of deep ocean environments on the corrosion of irons, steels and cast irons. To accomplish this, specimens of 47 different alloys were exposed at nominal depths of 2,350 and 5,500 feet for periods of time varying from 123 to 1,064 days. The corrosion rates of all the alloys, both cast and wrought, decreased asymptotically with time and became constant at rates vary- ing between 0.5 and 1.0 MPY after three years of exposure at a nominal depth of 5,500 feet in sea water. These corrosion rates are about one-third those of wrought steels at the surface in the Atlantic Ocean at Harbor Island, North Carolina. The corrosion rates of these same alloys in sea water at a depth of 2,350 feet were lower than those at the 5,500 foot depth and decreased with time. 13 In general, the corrosion rates of all the alloys exposed either adjacent to or partially embedded in the bottom sediments at the 5,500 foot depth decreased asymptotically with time and became constant at rates between 0.5 and 1.0 MPY after three years of exposure. The corrosion rates of the alloys in the bottom sediments at the 2,350 feet depth tended to increase with time. The corrosion rate of steel was not affected by nickel additions to 9 percent at either depth. Silicon and silicon-molybdenum cast irons were immune to corrosion in deep ocean environments, Type 502 steel was selectively attacked resulting in broad shallow pits and crevice corrosion, and its mechanical properties were impaired. The mechanical properties of the other alloys were not impaired. None of the steels were susceptible to stress corrosion crack- ing at stresses equivalent to 75 percent of their respective yield strengths. The corrosion products of the alloys were composed chiefly of alpha iron oxide, ferric oxide hydrate, ferrous hydroxide and Beta iron (III) oxide-hydroxide. Zinc (hot-dipped) (1.7 mils) and titanium-cadmium coatings failed to protect sheet steel for one year of exposure. A hot-dipped aluminum coating (4 mils) protected sheet steel for a minimum of one year whereas a sprayed aluminum coating (6 mils, sealed) protected sheet steel for three years. The mechanical properties of anchor chains were unimpaired. However, sea water penetrated the forged sockets of one type of chain as evidenced by corrosion at the bottoms of the sockets. The mechanical properties of Type 304 stainless steel cables in sizes 0.094, 0.125 and 0.187 inch diameter were decreased by a minimum of 85 percent due to corrosion of the internal wires while those of the larger diameter wires were unaffected. The breaking strength of a Type 304 stainless steel cable coated with 90 percent copper=10 percent nickel was not effected. The breaking strengths of the aluminum coated steel wire ropes were unaffected. The bare steel, zinc and aluminum coated steel and stainless steel wire ropes were not susceptible to stress corrosion cracking when stressed at 20 percent of their respective breaking loads. However, the Type 316 stainless steel wire rope lost 40 percent of its breaking strength due to corrosion of the internai wires. The breaking strengths of bare steel, zinc and aluminum coated 14 steel wire ropes, both stressed and unstressed, were umimpaired by exposure to deep ocean environments for periods of time as long as 1,064 days. However, based on visual observations zinc coatings corroded at faster rates than aluminum coatings on the wire ropes. ACKNOWLEDGMENTS The author wishes to acknowledge the generosity of Dr. T. P. May, Manager, Harbor Island (Kure Beach) Corrosion Laboratory, International Nickel Company, Inc. for granting permission to include his deep ocean corrosion data in this report. 15 90°0 90°0 €0°0O €0°0O SOO €0°0O STqPTien “Ay *sqouy ‘jueraing T 7°0 7°0 al! 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ST9FL ZO'O | S3uTseITeW-IN ZT /zi* VISH da ‘/8€V-WLSV 9EV-WLSV 9EV-WLSV yeeqs sraddog OTOL ISIV O101 ISIV O101 ISIV uory 34y3n0I1M 7 1 panuijuos ase9 ‘7Z-a adAj, ‘9T}TUSIZSNy ase9 ‘Sy adh ‘ITA TUaISsNy ase9 -‘y adAZ, SOTA JUaISNY 3se89 addy, ‘91, TUueQsny 3889 Z odAy SOTA TUaISNYy a € adAy, ‘oT TUAaASNy sep ‘uojyT ow + TS | yse9 ‘uojzy Is qseo “C# “UOIT eT TIONG ase9 “T# “UorT aTzIoONgG 3se®9 “@# ‘UOIT I0-IN 358) €2°0 “T# “UOTT 40-IN 89°0 sep ‘uojy IN paeprosey Jon | 3aseg ‘Suoazy Aeazy z0°0 - uot] OOWUV SL°O | CWO ISIV Ppspsjz0d 94 JON 4.6 pep rods 9y JON 40°S papiosey 2ON %O°€ Pepszod9oy JON LG S SuUTSeIEW-IN YT 80°0-1V 9€°O-TL | €1°8 (penutquos) *Z eTqeL 8 1 1203s AoT]V-MoT YyI3ueaIS-y3TH /Z QT aouetezey /T alte ee /TOONt - = = G*O Gas 70 | = =» 3 = S°O | GO°O zZos¢ adAL ISIV THON - = - GS°0 cL°4 = | 86°@ |@1O°® | Odo°o 87°0 | 90°0 zos ed4y ISIV ! (zo €0°1) z adAz THON ‘peztutwnty | | xeW xe | 99°09 | xeul THON ! | a8e8 gt ‘1y9-92¢v “o9ds wasv |oso’c ‘070°0 | =s2"0 | SLO P2COo “perpen es) —OONT | | Peproo0y ION qse9 ‘oa,qeus HM | -paey ‘oTZTUAIsNy —OONI ols - = OL? S66 |) Seu = 2 2 ase ‘¢-d /\ ! adAj, ‘oT, TUSISHY | H O ‘ THON = = 2 = 80°0 WS G6 || SE°% = | 2IO°O G77 asep ‘97-d | adkj, ‘2TRTUaISny | | + 3se9 ‘qz-d jFOONT | aes - =P 6rG GO | O¢ ea 8/9 - | addy ‘ot; tueasny | H i eoanog | 43430 | 09 n9 ow z9 IN is eee uy J |) earn | sa (penutquos) *Z7 oTqeL 19 Table 3. Condition of the Steels, As Received Wrought Iron As fabricated pipe AISI C1010 Hot rolled (mill) and pickled (laboratory) ASTM A36 Hot rolled (mill) and pickled (laboratory) ASTM A387, D Hot rolled (mill) and pickled (laboratory) HSLA Water quenched from 1650° to 1750°F and tempered at 1100° to 1275°F (mill), blast cleaned (laboratory) Hot rolled and pickled Water quenched from 1650°F and tempered at 1150° to 1200°F (mill), blast cleaned (laboratory) Hot rolled (mill) and pickled (laboratory) Water quenched from 1650° to 1750°F and tempered at 1150° to 1275°F (mill), blast cleaned (laboratory) Consumable electrode vacuum melt, hot rolled, annealed, cleaned and oiled Consumable electrode vacuum melt, hot rolled, annealed, cleaned and oiled AISI 4340 (200 KSI) Oil quenched from 1550°F, tempered for 1 hour at 750 oR blast bileened (laboratory) AISI 4340 (150 KST) Oil quenched | from 1550 OEE tempered for 1 hour at 1050° F, blast loaned (Laboratory) AISI Type 502 Annealed and pickled, No. 1 sheet finish (mill). continued 20 Table 3. (continued) Ni, Maraging (0.202) Electric furnace air melt, air cast, annealed, desealed and oiled Ni, Maraging (0.082) Electric furnace air melt, air cast, annealed, desealed and oiled (mill); NCEL unwelded, aged at 900°F for 3 hours, air cooled , then welded. Ni, Maraging Electric furnace air melt, air cast, annealed, aged at 950°F for 3 hours, air cooled, as rolled surfaces Ni, Maraging Electric furnace air melt, air cast, annealed, aged at 950 F for 3 hours, air cooled, surfaces ground to RMS-125 Austenitic, Type 4 As cast Cast Iron Nodular austenitic, As cast Type D-2C, Cast Iron Galvanized 18 gage 1.0 on BE Aluminized Type 2 Commercial quality, 1.03 ee sta 21 panuljuos THON —TIN / SboNI THON ~OONT / 97g 9N — SVN /TLISWN SONI THON —TYN /ZpONt sw —TSWN /Uosyn vii THON THON THON THON THON THON aoinos 1S) PPrMPPSPPSPPODVDD PrPrrTPAY PPUPOCO —uoTsoii09 1% jo ody, aed —ddTAeAD ° e e e e e ONArOTFTARANIMNA GO GO O otrsteMNNONONNnrAANOOHSO ortrnDOdN NTA OON mmo rm OD +t NH OOF 4 a}eY UOTSOIIOD) qo0q ‘yadaq S[9e7S pue suOAI JO SsazeY UOTSOIIOD “4 aTGeL sheq *aansodxq “0101 ISIV 69101 IstV jZOl0l ISTV 0101 ISIV jqOl0l ISI¥ O10 ISIV (2stda) O101 ISIV (228Td) O01 ISIV jer. ISIV OTOT ISIV OTOT ISIV COTOI ISIV S (estas O1OT ISIV (9381Td) O01 ISIV 243no0 1M 2u3N0IM qyZn0Iy 243nN01M 3Yysno0IM aysno4ry oow1y oowly oowly oowry oowly ooully 22 penuljuos T# WISH I# WISH hie os d-Z8€V WLSV a-L8€V WLSV d-L8€V WLSV d-Z8€V WLSV ad-L8€V WLSV PPPypaye 9€V WLISV 9€V WLSV Joo WLSV WISV n n ia n Nn n 1) 5>OOD0 5 PPYPono —Uo0TSo1109 skeg aoinos 1% yo adéy ‘ainsodxq (penutquos) “4 oT gel, 23 panuljuos /3a30N (3 30N (37 0N THON (Sago (7o30N (3 g0N ‘THON THON THON THON —TUN / et oON THON THON —TIUN /€T THON THON THON THON ao inos ! | | | sTqw 6‘O ‘ =oITADI anoncoa) |_| /*7 PPPVoUFoDD,DDVVY i=) Au opnPOnRAaD i] n n n n jo odAy OMNMANAMNAOSTNAN AM MFMNNTFOCH OANA GS tsenononea DAm~AHDOAN SNM e ooee4 woot oO ae ee a —hkdW ‘e384 uotsoiit0g /T 39004 ‘yadeq sXkeq (penutjuod) ‘aansodxq "y eTqeL AOTILV 24 panuljuoo _OONT /OONT JOonT ! 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Environmental Variables Variable Harbor Island, N. C. Pacific Ocean Surface 5,500 Feet variable, low 0.03 knot pH 7.6 Pressure 2475 psi Temperature DG hAG Oxygen eee vy a 34 Table 6. Stress Corrosion Tests Stress,| % Y.S. | Exposure,| Depth, |Number of | Number KSI Days Haters Specimens | Failed AISI 4340 (150 KSI) OWUMOUWOUWOUOUOUMO UO ORF FF OWWNWWWWNY WWW DY Ww SLOTS TOLOIS LOLOL LOEOVOR@ AISI 4340 (200 KSI) ./ of od ol 2) oD) oD ) 2) od off od od of WWWNWWWWMWWWND Ww SIOLOLOLOVOLORONOTOROtOrOorS HSLA No. 1 bwoowrf WWWW SOTO VOrS lo WW WH Ww OOeo © continued 35 Table 6. Stress Corrosion Tests (Cont'd) Stress,|% Y.S. | Exposure, Depth, |Number of | Number KSI Days Ft. Specimens | Failed AISI Type 502 ASTM A387, Grade D ASTM A36 18% Ni Maraging 18% Ni Maraging Welded 36 panuljuoo a-/8€V WLSV OLOL ISIV uorzy 2Yy8no0r i ee ee Ce Laad OS€°c Hldaa LHad 006°¢ “Hldad SHL Ladd Odd HONVHO LNGOddd ‘IVNIOTAO UOTSOTLIODN OF ang ST90e7S pue suUOAT FO Sat AAedorg TeotTueYydeW UT eSueyD JUSsoTeg ‘“/ OTqGePL 37 penuljuos ii Q°ESl WSS ¢ Iswa Si (ISM OST) Ove ISIV 6 Passel QUST IU (ISM OST) US Sih Ove” ISIV pail 9°681 ISN‘SA (ISM 002) TSS Ove ISIV 4 STF BOIL WEIS, ISM “SL (ISX 00Z) Ove? ISILV Bate QOL UHI ISM ‘SL “ON WISH Patel BEE UVES ISu ‘SL patel dS — ISSR TSU Sip e207 [Oe TTT LHI OSE*7Z “HLdad Laa4 00S‘S “HLdad HONVHO LNaXOddd uOTSOIIOD OJ Ong S{2x07S pue suOorT Fo SsaTAAedoAg TeoTUeydaW! 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Oceanographic data at STU sites. Corrosion Rate, MPY il | \7 7\ 0C0D0QPDPeEe0B Surface, Atlantic 22/ Surface, Pacific, Panama Canal— 5,500 2,350 5,500 2,350 4,500 4,500 4,250 5,600 Feet, Feet, Feet, eet, Feet, Feet, Feet, eet, 20/ Pacific, NCEL Racaskiies NOB ey) = Pacitic.. INCOa Pacific, tncoZ8/ 23/ Atlantic, Bae, MST Atlantic, Disc, MTA Atlantic, GI eS Atlantic, —— 200 Figure 3. 4 0 et Exposure, Days Corrosion rates of low carbon steels at various locations. Corrosion Rate, MPY Figure 4. 600 Depth, Feet 5,500 2,350 Armco Iron Wrought Iron AISI 1010 Wrought iron, surface, Panama Gana 129/ Mild steel, surface, Atlantic Exposure, Days Corrosion rates of wrought iron and Armco iron in sea water. >{- Mild Steel, Surface, At lantic20/ o - AISI 1010, NCEL 4 - A387, NCEL QO - HSLA No. VY - HSLA No. WV - HSLA No. O- HSLA No. @ - HSLA No. O - HSLA No. NCEL NCEL 5,600 Feet, Atlantic22/ NCEL tnco28/ NCEL INCO+E! tcoL8 © - HSLA No. Q-HSLA No. @ - HSLA No. tncoL8/ 9 -HSLA No. 9, incol8/ @- HSLA No. 10, tncol8/ ve ee ye ee we OON UU KEY NH SK a, ©-HSLA No. 11, rNncoL8/ << ! @ - A36, NCEL z ® - AISI 4340, NCEL BS a@- AISI 4130, NAECLL/ N74 YWi,-5,500 Feet ep aN WW - 2,350 Feet es SS : lites 25 Corrosion Rate, MPY lS Z = “ Upp, NS MET rr, me Mf 200 400 600 800 1000 1200 1400 Exposure, Days Figure 5. Corrosion rates of steels in sea water. *sqUdUlTpas WO2}I0q |Yyi UT S[aaqIS JO SazeI UOTSOIIOD *9g |ain3Ty : sKeq ‘ainsodxq 0021 OOOT 008 009 0047 002 0 THON ‘OCW - @ THON ‘OVE ISIV - 8 ONI ‘II °ON VISH - & ¢ ° (3 ° ¢ ° THON ‘/8EV - 9 % 7 THON “OTOT ISIV - 0 , 0 wee | “Up a KkdW ‘99BY uotsoisz09 *s] Tu I 0 T Q00T el] = NX Tp TweLIW - 309K 009°S - Z ‘ON VISH -™ DTIUe - G = ite Pee teeta - 3924 009°S au ISIV @ *1a9eM Bas aodUepTyUuOD Quedied cg ‘sanz i TI be Ui, WY, Sl no [eOF;9sTIeIS sodxq 9 00” : 002 (0) | ; VD». POT TW NG ate 0 ee Bea / LN ww me 7/7, 72207 OSEe‘z7-V 2907 006°6¢-O AVX a LLY YY pue 10384 Bas UDdUIT pes *sjUaUTpas WO30q ay UT U} 819998 DY AOJ SA2AAND [BOTISTISIS UPTpaW sXeq ‘ainsodxqg 6 e1n3TWq ee N RAW ‘22BY UOTsO1I09 JaqeM PIS UT [9aqS FO 2ReA UOFsSOAIOD dy} UO TeHITU Jo AIazFTY quesdiag ‘TeX IN °O[ ean3tq qe0q OLESZ ‘shea zon) 6 qeeq Oog's ‘shed 7901 VV 3007 OVO‘G ‘skeq IGL O /RTOONt N AdW ‘92eyY uotsorI09 *1928M B8S UT SUOIT SED JO saqzeI UOTSOIIOD “JI 21iN3Tq sXeq ‘oinsodxq @ “ON eTTIONG T “ON eTTI9NG “ON WNTWOTYD-TOYOTN “ON UNTUWOTYD-TeXOTN TOXOIN Aory (gp ié yj AdW 6238Y uotsor109 *sqUudUlTpas wW0320q ay. UT SUOIT JSBD JO sazeI UOTSOIIOD “°7Z{ aansty sXeq ‘ainsodxq 0 ee I, LMLALLLLEEL LITT T Z “ON eTTIONG T ‘ON eTFIONG Z “ON wnTWIOIYD-T2xOIN T °ON wnTwo1y9-TexOTN T2%OTN Aoay Ose‘z 00S*S ioe qeeq ‘“yqdeq dW ‘938yY uotsoi109 sXeq ‘aansodxq 0) 0 eee ae I | gp | KS, “€1 oan3ty v7] 00 N segvage vr @dd S) HW GA) N 7 a Q fe} ~m 6 4 - *s}uauTpes woz 0qG ay} UT suOIT JSeO DTAJTUaQSNe Jo saqei uoTsoOIIO) skeq OSGuCOOG aS qeog ‘yqdeq “71 ean3tg ~ AdW ‘a7eY uotso110) Biter: isi 00cT *SqUuaUitpes wWozIOq |Yy UF SUOIT 3SBD JO *“s}}WI]T edUapTyuo. quaoirzed ¢¢6 ‘SsaAaind [B9198T2eIS sMeq ‘ainsodxq 000T 008 009 00” Wega VD a y ZL S ~ 2004 oce‘z -V 3297 006°¢ -O “QT ean3ya ‘9qB8yY uo; s0I1I09 Adu sXKeq ‘ainsodxq 0 00 002 WTO | 3 Corrosion Rate, MPY Depth, Feet 55500) + A5550) Steels Cast Irons Austenitic Cast Irons Exposure, Days Figure 18. Statistical median curves for steels, cast irons and austenitic cast irons in sea water. Corrosion Rate, MPY 200 Figure 19. Depth, Feet 5,500 D0) Steels O @) Cast Irons A A Austenitic Cast 0 @ Irons 400 600 800 1000 Exposure, Days Statistical median curves for steels, cast irons and austenitic cast irons in the bottom sediments. APPENDIX MATHEMATICAL TREATMENT OF CORROSION DATA 65 The statistical median corrosion rate data for the steels after 400 days of exposure were treated by linear regression analysis to determine whether a mathematical expression could be obtained for calculating corrosion rates from oxygen concentration, temperature, and oxygen and temperature combined. The surface data were obtained from Figure 5 and the depth data from Figure 9. A linear expression, MPY = 0.5176°09 + 1.127, was obtained for the effect of oxygen. MPY 02 mils penetration per year concentration of oxygen in milliliters per liter of sea water. Corrosion rates calculated using this expression agreed very well with those calculated from weight loss determinations after 400 days of exposure as shown in Figure 1. The corrosion rates of the steels increased linearly with oxygen concentration. However, this expression is not applicable to other exposure time periods; for example, after 200 or 300 days of exposure. Curves of experimental corrosion rates for 200 and 300 days of exposure are not straight lines as shown in Figure 1. For these time periods, the corrosion rates of steels do not increase linearly with oxygen concentration; they more closely approach a hyperbolic relationship. Uncorroded steels corrode at high rates when first immersed in sea water or any oxygenated electrolyte because of the free access of the dissolved oxygen to the surface of the steel. As the time of exposure increases and the film of corrosion products forms, the corrosion rate decreases because the access of oxygen to the un- corroded surface is impeded by the corrosion product film. When the film of corrosion products becomes of such a thickness and per- meability that oxygen diffuses to the surface at a constant rate, the corrosion of the steel becomes constant with time and is known as being under diffusion control. This explains the non-linear increase in corrosion rates of steels with increase in oxygen con- centration after only 200 or 300 days of exposure; i.e., they were not completely under diffusion control. Corrosion rates calculated from exponential expressions for temperature and temperature and oxygen combined did not agree with experimental corrosion rates. 66 "S$]@O4S JO UOISOAIOD B44 UO UBBAXO jo 49a}4 *|-\V a41NbI4 (|/|w) ueBAxE skoq gop ‘404ndwo7> skvq QOp ‘|OsUeWIIedx y skoq QO€ ‘|Djuawtiadx skoqg 007% ‘|P}uaewisadxy 1SO1107 (Adw) aypy uo REFERENCES 1. 3g U. S. Naval Civil Engineering Laboratory Technical Note N-446: "Effects of the Deep Ocean Environment on Materials - A Progress Report" by K. 0. Gray, Port Hueneme, Calif., July 1962. U. S. Naval Civil Engineering Laboratory Technical Note N-657: "Environment of the Deep Ocean Test Sites (Nominal Depth 6,000 feet) Latitude 33946'N, Longitude 120°37'W"' by K. O. Gray, Port Hueneme, Calif., Feb 1965. U. S. Naval Civil Engineering Laboratory, Unpublished Oceano- graphic Data Reports, by K. O. Gray, Port Hueneme, Calif. U. S. Naval Civil Engineering Laboratory Technical Report R-182: "The Effects of Marine Organisms on Engineering Materials for Deep Ocean Use" by J. S. Muraoka, Port Hueneme, Calif., Mar 1962. U. S. Naval Civil Engineering Laboratory Technical Report R-329: "Deep Ocean Biodeterioration of Materials - Part I. Four Months at 5,640 feet" by J. S. Muraoka, Port Hueneme, Calif., Nov 1964. U. S. Naval Civil Engineering Laboratory Technical Report R-358; "Deterioration of Rubber and Plastic Insulation by Deep-Ocean Organisms'' by J. S. Muraoka, Port Hueneme, Calif., Mar 1965. U. S. Naval Civil Engineering Laboratory Technical Report R-428: "Deep Ocean Biodeterioration of Materials - Part III. Three Years at 5,300 Feet" by J. S. Muraoka, Port Hueneme, Calif., Feb 1966. U. $. Naval Civil Engineering Laboratory Technical Report R-456: "Deep Ocean Biodeterioration of Materials - Part IV. One Year at 6,800 Feet" by J. S. Muraoka, Port Hueneme, Calif., Jun 1966. U. S. Naval Civil Engineering Laboratory Technical Note N-458: "Emplacement of the First Submersible Test Unit on the Sea Floor - One Mile Deep'' by R. E. Jones, Port Hueneme, Calif., Feb 1963. 68 10. 11. WA 13} 14. IL3)o 16. 17. 18. 19. U. S. Naval Civil Engineering Laboratory Technical Report R-369: "Design, Placement and Retrieval of Submersible Test Units at Deep Ocean Test Sites" by R. E. Jones, Port Hueneme, Calif., May 1965. U. S. Naval Civil Engineering Laboratory Technical Note N-705: "Retrieval of STU II-1 by Acoustical Method Beacon" by R. E. Jones and R. Krutenat, Port Hueneme, Calif., Nov 1966. U. S. Naval Civil Engineering Laboratory Technical Note N-782: "Recovery of Submersible Test Unit I-1" by C. K. Paul, Port Hueneme, Calif., Oct 1965. U. S. Naval Civil Engineering Laboratory Technical Report R-504: "Corrosion of Materials in Hydrospace'' by Fred M. Reinhart, Port Hueneme, Calif., Dec 1966. U. S. Naval Civil Engineering Laboratory Technical Note N-605: "Preliminary Examination of Materials Exposed on STU I-3 in the Deep Ocean - (5,640 Feet of Depth for 123 Days)," by Fred M. Reinhart, Port Hueneme, Calif., Jun 1964. U. S. Naval Civil Engineering Laboratory Technical Note N-695; "Examples of Corrosion of Materials Exposed on STU II-1 in the Deep Ocean (2,340 Feet of Depth for 197 Days)" by Fred M. Reinhart, Port Hueneme, Calif., Feb 1965. U. S. Naval Civil Engineering Laboratory Technical Note N-781: "Effect of Deep Ocean Environments on the Corrosion of Selected Alloys" by Fred M. Reinhart, Port Hueneme, Calif., Oct 1965. U. S. Naval Civil Engineering Laboratory Technical Note N-793: "Visual Observations of Corrosion of Materials on STU I-1 After 1,064 Days of Exposure at a Depth of 5,300 Feet in the Pacific Ocean" by Fred M. Reinhart, Port Hueneme, Calif., Nov 1965. Dr. T. P. May, unpublished data. Naval Air Engineering Center, Aeronautical Materials Laboratory Report No. NAEC-AML-2132 "Evaluation of Metallic Materials Exposed to the Deep Ocean Environment at 5,640 Feet for 123 Days" by John J. De Luccia and Edward Taylor, Philadelphia, Pa., 22 Jun 1965. 69 20. Zlke ed 6 Dre 24. 23) 0 26. Dalle AS 23) Dr. T. P. May, personal correspondence. Naval Research Laboratory Report 5153, "Corrosion of Metals in Tropical Environments, Part 3 - Underwater Corrosion of Ten Structural Steels" by B. W. Forgeson, C. R. Southwell and A. L. Alexander, Washington, D. C., 8 Aug 1958. Naval Research Laboratory Memorandum Report 1634, "Marine Corrosion Studies - Third Interim Report of Progress" by B. F. Brown and others, Washington, D. C., Jul 1965. Naval Applied Science Laboratory Report, "Corrosion at 4,500 Foot Depth in Tongue-of-the-Ocean" SRO04-03-01, Task 0589, Lab. Project 9400-72, Technical Memorandum 3, by E. Fischer and S. Finger, Brooklyn, New York, Mar 1966. Naval Applied Science Laboratory Report "Retrieval, Examination and Evaluation of Materials Exposed for 102 Days on NASL Deep Sea Materials Exposure Mooring No. 1", SF 0099-03-01, Task 1481 and (SF-02-030-06 Task 1003) Lab. Project 9300-6, Technical Memorandum 4 (and Lab. Project 9300-7), A. Anaustasio, Brooklyn, New York, Nov 1965. Naval Research Laboratory Report 5370, "Corrosion of Metals in Tropical Environments, Part 4 - Wrought Iron” by C. R. Southwell, B. W. Forgeson and A. L. Alexander, Washington, D. C., Oct 1959. A. C. Redfield. "Characteristics of Sea Water", in Corrosion Handbook, edited by H. H. Uhlig. New York, Wiley, 1948, p. 1111. F. L. LaQue. "Behavior of Metals and Alloys in Sea Water," in Corrosion Handbook, edited by H. H. Uhlig. New York, Wiley, 1948, p. 390. C. P. Larrabee. '"'Corrosion Resistance of High-strength-low-= alloy Steels as Influenced by Composition and Environment ," Corrosion, Vol. 9, No. 8, Aug 1953, pp. 259-271. F. L. LaQue and H. R. Copson, "Corrosion Resistance of Metals and Alloys" Second Edition, ACS Monograph No. 158, Reinhold Publishing Corp., New York, New York, 1963, pp. 74-76. 70 30. 31. 326 33} 34. H. H. Uhlig ''Corrosion and Corrosion Control" John Wiley and Sons, Inc., New York, 1963, p. 80-85. L. L. Sehreir "Corrosion", Vol. 1, John Wiley and Sons, New York, 1963, p. 232. L. L. Schreir "Corrosion", Vol. 1, John Wiley and Sons, New York, 1963, p. 227. U. S. Naval Research Laboratory. NRL Memorandum Report 1383, "Abyssal Corrosion and Its Mitigation - Part II. Results of A Pilot Exposure Test" by B. W. Forgeson, et al, Washington, D. C., Dec 1962. U. S. Naval Civil Engineering Laboratory Technical Note N-859: "Corrosion Rates of Selected Alloys in the Deep Ocean" by W. S. Haynes, Ph.D. and J. B. Crilly, Port Hueneme, Calif., 17 Nov 1966. 7\ ; - ae itl ee Lae ae tctars 1 3.5 Sale Cee i ag le STGP Y Ses LT ph aK, ce 5 0 Gat 7 i ql , ae ian ie. Ve bana eres, Ae woth: Pai: itn 4 catia! "Sit spies Oe Wits Mab cme aglt's Fife) a Thee P > Hr) 2 Wad ‘ ot. Pe ala Y aoe fa i PS rae a font y r a , vie Bi l ¥ athe a ‘ap me eA a Oe wat i it Chey i “ee: May ht ’ 1 iw ; > h : y + i Pp . ‘ - cay A ee Se vowel ‘Tahal be eae faa | iby tach bus Pas .< akties | " ; , Poh WetMe a. fiber) OL r te vy uw aa © g 49 , » i of I 7 ¥ Moths? eve eyo al Geen sea be) Be) Se my 1S Gael. st. ck avo TA henna, les 3 ee aes ae ron Sea, 4 RR AA ; nee Pad y i eee \y os ] i a. y i . > i . ¥ > we { cA i A Rake { ey 4 x d , j } 0 ee ee : c Wy ny +e ‘ i he : : i i 1 j J 1 Wk ‘ Y y 4 t ‘ Ay : Day : : t a4 er 4 i i i ¥ “ee u , \ + i = , = { 4 y 4 }, ¥ j at i % : \ ; f j ‘ , , ty - i i 3 Ye Be m La ' if \ ' oN 4 i . Unclassified Security Classification DOCUMENT CONTROL DATA - R&D (Security classification of title, body of abstract and indexing annotation must be entered when the overall report ia classified) 1. ORIGINATING ACTIVITY (Corporate author) 2a. REPORT SECURITY CLASSIFICATION U. S. Naval Civil Engineering Laboratory Unclassified 3. REPORT TITLE CORROSION OF MATERIALS IN HYDROSPACE - PART I. IRONS, STEELS, CAST IRONS, AND STEEL PRODUCTS 4. DESCRIPTIVE NOTES (Type of report and inclusive dates) 5. AUTHOR(S) (Last name, first name, initial) Reinhart, Fred M. 6. REPORT DATE 7a. TOTAL NO. OF PAGES 7b. NO. OF REFS July 1967 7\ 34 Ba. CONTRACT OR GRANT NO. 94. ORIGINATOR'S REPORT NUMBER(S) b. PRosEcT NO. Y-FO15-01-05-002A 9b. OTHER REPORT NO(S) (Any other numbers that may be assigned this report) el LPN ILITY/LIMITATION NOTICES 12. SPONSORING MILITARY ACTIVITY Naval Facilities Engineering Command Internal Working Paper Washington, D. C. 20390 13. ABSTRACT 3 A total of 1300 specimens of 47 iron base alloys were exposed at depths of 2,340, 2,370, 5,300, 5,640 and 6,780 feet at two sites in the Pacific Ocean for 197, 402, 1064, 123, 751 and 403 days respectively to determine the effects of deep ocean environments on their corrosion behavior. Corrosion rates, pit depths, types of corrosion, changes in mechanical properties, effects of stress, and analyses of corrosion products are presented. The corrosion rates of all the alloys, both cast and wrought, decreased asymptotically with duration of exposure and became constant at rates varying between 0.5 and 1.0 mils per year after three years ef exposure in sea water and partially embedded in the bottom sediments at a nominal depth of 5,500 feet. These corrosion rates are about one-third those at the surface in the Atlantic Ocean. At the 2,350 foot depth, the corrosion rates in sea water also decreased with duration of exposure but tended to increase slightly with duration of exposure in the bottom sediments. The corrosion rates at the 2,350 foot depth were less than those at the 5,500 foot depth. The mechanical properties were unimpaired. Silicon and silicon-molybdenum cast irons were uncorroded. A sprayed 6 mil thick coating of aluminum protected steel for a minimum of three years and a hot dipped 4 mil thick coating of aluminum protected steel for a minimum of 13 months while a hot dipped 1.7 mil thick coating of zinc protected steel for about 4 months. DD inetd 1473 0101-807-6800 lncilassiicied Security Classification Unclassified Security Classification KEY WORDS Corrosion materials irons steels iron alloys hydrospace ocean environment INSTRUCTIONS 1. ORIGINATING ACTIVITY: Enter the name and address of the contractor, subcontractor, grantee, Department of De- fense activity or other organization (corporate author) issuing the report. 2a. REPORT SECURITY CLASSIFICATION: Enter the over- all security classification of the report. Indicate whether “Restricted Data’ is included. Marking is to be in accord ance with appropriate security regulations. 2b. GROUP: Automatic downgrading is specified in DoD Di- rective 5200.10 and Armed Forces Industrial Manual. Enter the group number. Also, when applicable, show that optional markings have been used for Group 3 and Group 4 as author- ized. 3. REPORT TITLE: Enter the complete report title in all capital letters. Titles in all cases should be unclassified. If a meaningful title cannot be selected without classifica- tion, show title classification in all capitals in parenthesis immediately following the title. 4. DESCRIPTIVE NOTES: If appropriate, enter the type of report, e.g., interim, progress, summary, annual, or final. Give the inclusive dates when a specific reporting period is covered. 5. AUTHOR(S): Enter the name(s) of author(s) as shown on or inthe report. Enter last name, first name, middle initial. If military, show rank and branch of service. The name of the principal author is an ahsolute minimum requirement. 6. REPORT DATE: Enter the date of the report as day, month, year; or month, year. If more than one date appears on the report, use date of publication. 7a. TOTAL NUMBER OF PAGES: The total page count should follow normal pagination procedures, i.e., enter the number of pages containing information. 7b. NUMBER OF REFERENCES: Enter the total number of references cited in the report. 8a. CONTRACT OR GRANT NUMBER: If appropriate, enter the applicable number of the contract or grant under which the report was written 8b, 8c, & 8d. PROJECT NUMBER: Enter the appropriate military department identification, such as project number, subproject number, system numbers, task number, etc. 9a. ORIGINATOR’S REPORT NUMBER(S): Enter the offi- cial report number by which the document will be identified and controlled by the originating activity. This number must be unique to this report. 9b. OTHER REPORT NUMBER(S): If the report has been assigned any other report numbers (either by the originator or by the sponsor), also enter this number(s). 10. AVAILABILITY/LIMITATION NOTICES: Enter any lim itations on further dissemination of the report, other than those’ imposed by security classification, using standard statements such as: (1) ‘Qualified requesters may obtain copies of this report from DDC.’’ (2) ‘‘Foreign announcement and dissemination of this report by DDC is not authorized ’’ (3) ‘‘U. S. Government agencies may obtain copies of this report directly from DDC. Other qualified DDC users shall request through e “‘U. S. military agencies may obtain copies of this report directly from DDC. Other qualified users shall request through (5) ‘All distribution of this report is controlled. Qual- ified DDC users shall request through If the report has been furnished to the Office of Technical Services, Department of Commerce, for sale to the public, indi- cate this fact and enter the price, if known 11, SUPPLEMENTARY NOTES: Use for additional explana- tory notes. 12. SPONSORING MILITARY ACTIVITY: Enter the name of the departmental project office or laboratory sponsoring (pay ing for) the research and development. Include address. 13. ABSTRACT: Enter an abstract giving a brief and factual summary of the document indicative of the report, even though it may also appear elsewhere in the body of the technical re- port. If additional space is required, a continuation sheet shall be attached. It is highly desirable that the abstract of classified reports be unclassified. Each paragraph of the abstract shall end with an indication of the military security classification of the in- formation in the paragraph, represented as (TS), (S), (C), or (U). There is no limitation on the length of the abstract. How- ever, the suggested length is from 150 to 225 words. 14. KEY WORDS: Key words are technically meaningful terms or short phrases that characterize a report and may be used as index entries for cataloging the report. Key words must be selected so that no security classification is required. Identi- fiers, such as equipment model! designation, trade name, military project code name, geographic location, may be used as key words but will be followed by an indication of technical con- text. The assignment of links, rales, and weights is optional. Unclassified Security Classification eu m3 fv ne ti hen a1} sree ipa ee) ve ya i of Li ) { Ue a Ry SO { Sh) i ‘s ; ' PA ’ di rx