Rolling contact fatigue properties of ultrasonic surface rolling treated 25CrNi2MoV steel under different lubricant viscosities

Ultrasonic surface rolling (USR) treatment was subjected to the 25CrNi2MoV shaft steel surface. The rolling contact fatigue (RCF) properties of treated samples under different lubricant viscosities were investigated. Results showed that the USR treatment significantly refined the surface grains, improved the surface hardness and generated a compressive residual stress (CRS) field in the subsurface layer. Reduced surface roughness changed the lubrication regime between contact pairs and relieved the local surface stress concentration. USR treatment is an effective way to improve the RCF life under high lubricant viscosity. Moreover, the dominant failure mode of USR treated sample was delamination.