Springer Online Journal Archives 1860-2000
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Conclusions 1. Additional alloying of the case on steels 25KhGT and 25KhGM with nitrogen increases the hardenability of the case only with low carbon concentrations—up to 0.65% C for steel 25KhGT and up to 0.5% C for steel 25KhGM. At higher carbon concentrations in the case (0.7–0.9%) nitrogen lowers the hardenability. 2. The hardenability of steel 25KhGM after carburizing and carbonitriding is higher than that of steel 25KhGT. 3. The lower hardenability of high-carbon sections of the case is due to impoverishment of the solid solution in chromium with formation of chromium nitrides and the development of various defects in the structure. 4. Two types of defects exist in the carbonitrided case-fine dark inclusions in the field of the microsection, apparently micropores formed due to dissociation of finely dispersed chromium nitrides, and a dark component, voids formed during dissociation of alloyed carbonitrides of the cementite type that are filled with graphite and secondary oxides.
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