METHOD FOR HARDENING TOOLS MADE FROM CARBON STEELS Russian patent published in 1998 - IPC

FIELD: heat treatment; may be used in hardening the parts complicated in shape, made of carbon steel, for instance, threading and knurling tools for hardness over 61 HRCe. SUBSTANCE: method includes heating up to 780-820 C, holding and cooling. In this case cooling down to 400-200 C is carried out in 5-15-% aqueous solution of common salt at temperature of 15-30 C, and further cooling in the martensite interval of temperatures is carried out in 5-15-% aqueous solution of common salt at temperature of 90-100 C with further cooling in the air. EFFECT: higher efficiency. 1 tbl