Rolling contact fatigue resistance and damage evolution of carburized bearing steel treated by surface ultrasonic rolling process (SURP)

The impacts of the surface ultrasonic rolling process (SURP) on the surface morphology, surface microstructure, residual stress distribution, and rolling contact fatigue (RCF) properties of G20Cr2Ni4A carburized bearing steel were studied in this research. The results show that when the RCF rolling direction is perpendicular to the grinding direction, the fatigue peeling of the raceway surface is more serious. SURP not only reduces surface roughness but also enhances the residual compressive stress and hardness of the surface layer, allowing it to resist the initiation and propagation of surface cracks and enhancing RCF life. Fatigue cracks are easily formed between the ground layer and the matrix, according to microscopic analyses of fatigue crack initiation and propagation on the original sample surface. These cracks have the potential to spread down the ground layer, causing the shallow layer of approximately 1 mu m to spall off. They also promote crack propagation into the matrix and shorten fatigue life. SURP can cause the ground layer to peel off, making fatigue cracks on the surface more difficult to form and enhancing contact fatigue life.