Quenching of cold-heading dies of carbon tool steels

1. When cold-heading dies of carbon tool steel are quenched the depth of the hardened layer increases from 2.2 to 2.7 mm with an increase of the water pressure from 1 to 8 atm, and the hardness of the surface layer increases from HV 650 to HV 725. 2. The durability of the die increases with the hardness and the depth of the hardened layer. 3. Dies with a working diameter up to 6 mm should be quenched at water pressures of 4–5 atm, and with a working diameter over 6 mm at water pressures of 6–8 atm.