METHOD OF NITRIDE HARDENING OF STEEL WITH DOUBLE THERMOCHEMICAL TREATMENT Russian patent published in 2002 - IPC

FIELD: mechanical engineering; applicable in manufacture of steel machine parts and tools with surface hardening. SUBSTANCE: method includes preliminary treatment of steel for diffusion saturation of surface and building up of sublayer in the form of carbonitriding at temperature of 800-820 C with use of triethanolamine. After carbonitriding, nitriding is carried out through thickness less than that of carbonitriding sublayer. After nitriding, hardening, cold treatment and tempering are carried out. Control of thickness of diffusion layer is performed after carbonitriding and nitriding, and surface hardness is checked after hardening, cold treatment and tempering. Carbonitriding of articles made of steel 38X2MYuA is carried out at 800 C, and steel OChNZMa, at 820 C. Favorable properties of diffusion layer makes it possible to manufacture tools from structural steels instead of tool steels. EFFECT: higher hardness, heat resistance and cutting properties of diffusion layer of articles from alloyed steels, economical advantage in equipment preservation and power saving. 2 cl, 2 dwg, 3 tbl, 2 ex