. Transactions. FiQ. 42.—In same area as Fig. 31 after a 24-hr. draw at 200° C Etched 10 SEC. with 4 PER CENT. NITRIC ACIV. X 500. 286 NITROGEN IN STEEL AND THE EROSION OF GUNS Other Alloy Steels.—The object of treating a large number of alloysteels 20 hr. in NH 3 at 650° C. and, in some cases, at 750° C. was to observethe depth of the case formed and gather an idea of the effect of the addedelement in retarding or accelerating this reaction. The method is farfrom quantitative. For instance, two steels, each of per cent,carbon, per cent, chromium, one of per cent, vanadium, andt
. Transactions. FiQ. 42.—In same area as Fig. 31 after a 24-hr. draw at 200° C Etched 10 SEC. with 4 PER CENT. NITRIC ACIV. X 500. 286 NITROGEN IN STEEL AND THE EROSION OF GUNS Other Alloy Steels.—The object of treating a large number of alloysteels 20 hr. in NH 3 at 650° C. and, in some cases, at 750° C. was to observethe depth of the case formed and gather an idea of the effect of the addedelement in retarding or accelerating this reaction. The method is farfrom quantitative. For instance, two steels, each of per cent,carbon, per cent, chromium, one of per cent, vanadium, andthe other of per cent, vanadium, would not give in a half-dozen experi-ments consistent results as regards the depth of penetration. Such finedistinctions are beyond the scope of this method. It does, however, givea broad general idea of the effect of different families of elements. The. Fig. 43.—cjame as Fig. 28 after drawing 24 hr. at 200° C. Extreme outside EDGE SHOWS NEW INTERCRYSTALLINE CONSTITUENT. EtCHED 10 SEC. WITH 4 PERCENT. NITRIC ACID. X 500. writer does not feel that an elaborate exposition of the 300 or 400 experi-ments, each taking 20 hr. and many of them repeated several times,would be interesting. He will therefore briefly give only his nickel and manganese, the case formed etches lighter than thenormal metal and shows an austenitic appearance. With chromium,tungsten, molybdenum, uranium (and to a less extent with silicon,aluminum, and titanium), the case is darker after etching than the un-affected metal and the original structure remains visible. Silicon, up to4 per cent., seems to have no effect on the depth of the case; and withlow-carbon content, the piece is affected clear through showing no moreresistance than a corresponding low-carbon steel low in silicon. Exam-ples of light and dark cases are shown in Figs. 44 and 45. Th
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Keywords: ., bo, bookcentury1800, bookdecade1870, booksubjectmineralindustries
