Mild Annealing
Heating at 610-850 C, cooling slowly in the furnace. This will give a maximum Brinell hardness of 295.
Stress Relief
Slow heating to 650 C, holding for 1-2 hours at this temperature, followed by cooling in air. This operation is performed to reduce distortion during heat treatment.
Quenching
Heating to 880-910 C followed by quenching in air.
When quenching on oil with a temperature of - 180-220 C.
The hardness after quenching is 56 HRC.
Forging
Heating to 1100-900 C.
Hardness after quenching: 56 HRc
Hardness after annealing: 295HV