METHOD OF THERMOCYCLIC TREATMENT OF HIGHCHROMIUM TOOL STEEL FOR SECONDARY HARDNESS Russian patent published in 2002 - IPC

FIELD: metallurgy; heat treatment of high-chromium tool steels for manufacture of tools and machine elements. SUBSTANCE: proposed method consists in repeated heating above Ac₁ by 250 to 300 C and delay of 8 to 10 s per millimeter of section, cyclic cooling in melt of salts to temperature of 680 to 750 C at holding at this temperature for 15 to 20 s per millimeter of section and cooling in oil after heating in last cycle followed by tempering performed at temperature of 520 to 540 C in three stages each continued for an hour. Hardness HRC is equal to 62. EFFECT: enhanced resistance of tools due to increased secondary hardness and wear resistance. 1 tbl, 2 ex