METHOD OF HARDENING DIE STEELS Russian patent published in 2002 - IPC

FIELD: metallurgy, more particularly chemical heat treatment of semi and heat resistant die steels. SUBSTANCE: method comprises preparation of base by mixing powders containing wt %: (40B₄C+60Na₂B₄O₇), 40-60; B₂O₃, 25-35 and Na₂S, 15-25 and filled with carbamide filler, applying paste followed by boration and carbonitration for hardening purposes. During heating operation, isothermal maintenance is carried out at 540- 580 C. After isothermal maintenance cooling in oil and tempering may be accomplished at 560-580 C. EFFECT: higher resistance of die is attained due to lower microhardness and microspalling of diffusion layers and lower friction coefficient. 1 tbl