. Transactions. er Treated above critical change 48 hr. in NH3 at 650° C. Etched 15 4 per cent, nitric acid. X 25. and polished and etched. The entire end is shown in Fig. 27, the hghtarea being the area opposite the slot during treatment. This area isshown in Fig. 28; this grades off into the structure shown in Fig. 29,then Fig. 30, then Fig. 31, which last is characteristic of all the restof the dark area. For brevit^^ from here on these and similar structureswill be referred to as austenitic. Fig. 28, martensitic, Figs. 29 and 30,Widmannstattian, Fig. 31. The martensitic a
. Transactions. er Treated above critical change 48 hr. in NH3 at 650° C. Etched 15 4 per cent, nitric acid. X 25. and polished and etched. The entire end is shown in Fig. 27, the hghtarea being the area opposite the slot during treatment. This area isshown in Fig. 28; this grades off into the structure shown in Fig. 29,then Fig. 30, then Fig. 31, which last is characteristic of all the restof the dark area. For brevit^^ from here on these and similar structureswill be referred to as austenitic. Fig. 28, martensitic, Figs. 29 and 30,Widmannstattian, Fig. 31. The martensitic area is rarely encounteredspread out, as here, but usually is a very narrow zone, if it is visible at always etches to a purplish color with nitric acid. A third sample of per cent, carbon and per cent, nickel wasused to make 60 Charpy bars. Of these, 15 were treated 20 hr. in NH3at 700° C, first heating to 850° C. The rest were given the same heat 278 NITROGEN IN STEEL AND THE EROSION OF GUNS. Fig. 28.—Within light area op Fig. _i ; uirusnE notch during treatmentAusTENiTic. Etched 15 sec. with 4 per cent, nitric acid. X 500.
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Keywords: ., bo, bookcentury1800, bookdecade1870, booksubjectmineralindustries
