Effects of surface defects on rolling contact fatigue of M50 steel with consideration to both the transgranular and intergranular damage

Surface-initiated pitting and subsurface-initiated spalling of M50 bearing steel were investigated, considering transgranular and intergranular damage. The damage initiation and propagation for contact surface with defects produced by different size particles were analyzed using integrated model combined continuum damage method (CDM) and cohesive zone method (CZM). Pitting and spalling mechanism, and defect size effect on damage evolution were discussed. The results indicated both pitting and spalling include intergranular and transgranular damage evolution. As the defect size increases, the RCF mode change from spalling to pitting. Damage evolution mode of spalling and pitting is the plastic deformation and damage accumulation mode, respectively. Moreover, the prediction accuracy for the damage evolution of the integrated model is higher than single-CDM and single-CZM models.