PRODUCTION OF SMALL-SIZE CUTTING TOOLS FROM HIGH-SPEED STEEL Russian patent published in 2015 - IPC C21D9/22 

FIELD: process engineering.

SUBSTANCE: invention relates to metallurgy, particularly, to heat treatment of fast steel for surface hardening of cutting tool made, primarily, of forged or powder fast steel. To up the cutting tool life, tool made of fast steel is subjected to heat cycling in the internal of temperatures between martensite point and fusion point. Stepwise quenching is started from the temperature higher than that of polymorphic transformation with heating to this end combined with the last heating at heat cycling to allow tempering thereafter. Note here the tool hardening cooling is performed in two steps. First, cooling is performed in salt bath at 630-650°C held thereat for 0.5-1.5 min and cooled in oil. Heat treatment of fast steel causes developed disintegration of structure along with increase in amount of wear-proof MeC-type carbides and martensite alloying degree. Now, mosaic-discrete and functional-gradient structures are formed to increase tool life at cutting of hard-to-machine alloys.

EFFECT: longer service life.

2 cl, 1 tbl