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Full text of "Metallurgy Of Cast Iron"

CHAPTER LXV.
DISCOVERY OF EVILS IN CASTING TEST BARS FLAT.
At the meeting of the American Society of Mechanical Engineers held in New York City the week of December 3, 1894, the author, in a discussion on testing, briefly called attention to the series of tests seen on page 493. Before asking the reader to review the tests, the author wishes to comment on principles involved and what they demonstrate to us in emphatically proving that certain practices some follow are not correct. It is A\rell known that the past practice in moulding test bars has been upon the principle of casting them flat, and also that the form generally used has been square or rectangular in preference to the round form cast on end which, the author is pleased to note, has attracted much attention and is now (1901) adopted by many as the only correct method to test the physical properties of cast iron. The author will now advance more proofs to show that the round test bar cast on end is the best method which we can adopt to reduce erratic results in testing to the minimum.
Early in 1894, the author discovered that in testing a bar cast flat for its transverse strength, by applying the load on the upper cast surface a much greatermously passim; ivsuhit ions recommending the round bar cast on end as the most suitable for test in;,; cast iron. This n-NoJnli«»n also recommends that bars should not In* smaller titan one and one-half inches diameter. The somitT all coiiu* to ivcoj^ni/f the advisability of adopt in^1 tlir abovr ret'oin* nu'ndutions, though many may «lt*sin% to use as small as i 'ij-itu'h cliami'trf bars, which may oft«*n bt* juTinis-sibli- with soft grades, th«' brttrr for all hjtnvstrd in or making tise of test rcH,'ords, An aeeount of the.* A, F. A.'s work in brin^'iuv,' about the abo\c- rei'nm-iiH/iidatioiis is found in Chapter I,XX,, par,*-*; :;y.| in r,.s.j. and attacked the usual formulae for loaded beams asound burs..........................*fi$7 "