Synergistic effects of a combined surface modification technology on rolling contact fatigue behaviors of 20CrMoH steel under different contact stresses

Ultrasonic surface rolling (USR), carburizing and the combined (Carburizing + USR) strengthening method were applied on the 20CrMoH steel, and the rolling contact fatigue (RCF) mechanisms of 20CrMoH steel subjected to different strengthening methods are analyzed. Results indicated that the combined strengthening method effectively increased the surface hardness value from 370 HV0.2 to 900 HV0.2, produced the highest residual compressive stress (RCS) value of −920 MPa and markedly reduced the surface roughness value to 0.48 μm. Under the Hertz contact stress of 2.02 GPa, the RCF life of the combined treated samples increased by 100% compared to the carburized samples, and the delamination mainly occurred. Surface roughness and RCS are important factors for anti-RCF failure.