Effect of Tempering Temperature on Microstructure and Properties of GCr15 Bearing Steel

GCr15 steel is widely used in bearing. The tempering temperature has a significant effect on its properties. The effect of different tempering temperature on hardness, residual austenite and surface residual stress of GCr15 steel was investigated. The result shows that with the increasing of tempering temperature in the range of 165~300℃, the hardness HRC of the tested steel decreased from 61.7 to 56.2 , the residual austenite from 9.88% to 3.26% and the surface residual stress from 706.8 MPa to 382.2 MPa, accompanied with the gathering and growth of carbide. The microstructure is mainly composed of needle-type martensite, grain-type carbide and little residual austenite. This study provides reference for establishing low-temperature tempering process for GCr15 steel.