Effect of Adding Tempering Process on Deformation of GCr15 Bearing Steel Ring

A tempering process (150 ℃×2 h tempering+superfinishing) was added after grinding of the original manufacturing process of GCr15 bearing steel ring (raw material forging→annealing→turning→quenching→tempering→grinding→assembly). The microstructure, residual stress and roundness of the bearing ring were studied and compared before and after adding tempering process, and the effect of adding tempering process on the deformation was analyzed. The results show that after adding tempering process, the microstructure of the bearing ring still mainly consisted of lath matensite, retained austenite and spherical carbide particles; comparing with those under the original process, the fine carbide particle amount increased and the retained austenite content decreased. After adding tempering process, the roundness of the inner and outer surfaces of the bearing ring was reduced by 80% and 60%, respectively, indicating the deformation was reduced significantly. After adding tempering process, residual stresses in the ring decreased and tended to be evenly distributed, and the further precipitation of fine carbides inhibited the strain-induced martensitic transformation, thereby the deformation of the bearing ring decreased and the dimensional stability increased.