Abstract: Rolling contact fatigue performance is among the most important issues for applications of bearing steels. In this work, a recently developed surface modification technique, surface mechanical rolling treatment, was applied on a rare-earth addition bearing steel. And rolling contact fatigue behavior of treated samples was compared with that of as-received counterparts at different contacting stresses. The results demonstrated that a 700 µm-thick gradient nanostructured surface layer is produced on samples by surface mechanical rolling treatment. The grain size decreases while the microhardness increases gradually with decreasing depth, reaching ∼23 nm and ∼10.2 GPa, respectively, at the top surface. Consequently, the rolling contact fatigue property is significantly enhanced. The characteristic life of treated samples is ∼3.2 times that of untreated counterparts according to Weibull curves at 5.6 GPa. Analyses of fatigue mechanisms demonstrated that the gradient nanostructured surface layer might not only retard material degradation and microcrack formation, but also prolong the steady-state elastic response stage under rolling contact fatigue.

Key words: Rare earth addition bearing steel, Surface mechanical rolling treatment, Rolling contact fatigue, Gradient nanostructured, Microcrack