Evaluation of the influencing factors of combined surface modification on the rolling contact fatigue performance and crack growth of AISI 52100 steel

In this study, the combined treatment technology of shot peening (SP) and ultrasonic surface rolling (USR) were applied to the surface modification of AISI 52100 steel. The results revealed that SP, USR and combined treatment effectively improved the microhardness and residual stress of the alloy; however, SP and combined treatment were often accompanied by increased surface roughness. A nanocrystalline structure layer was prepared on the surface of the material through combined treatment, and the reason for the formation of the nanocrystalline structure layer was explained in detail. Compared with ceramic beads, the combined treatment of SP with steel beads was beneficial. The surface hardness and residual stress were improved while the minimum surface roughness was obtained. Under this process, the RCF life was significantly increased. Studies have shown that with the increased of RCF life, crack initiation transferred from the surface to the subsurface, and the crack depth increased significantly.