Heat treatment specifications and hardness requirements of various spring steels

Steel hardening temperature Hardening medium hardness requirements tempering temperature cooling medium hardness requirements application range

65 780-830 Water or oil 400-600 coil springs and spring washers with wire diameters less than 12-15mm

65Mn 810-830 Oil or water >60 370-400 water 42-50 5-10mm plate spring and 7-10mm coil spring

50CrV 850-870 Oil >58 400-55 Water 45-50 Large and important leaf springs and coil springs

50CrV 850-870 oil >58 370-420 45-52 High temperature springs operating below 300C

60Si2MnA 860-880 oil >60 500-520 water HB363-444 Plate spring with thickness of 8-12mm