Study on Fretting Wear Properties of GCr15 Steel Via Ultrasonic Surface Rolling Process

Abstract Ultrasonic surface rolling (USR) was applied to GCr15 steel with different static loads and passes to improve the friction and wear properties, and then the fretting wear mechanism of GCr15 steel after USR treatment was systematically investigated. The results showed that the specimens treated by the USR had lower surface roughness and significantly increased compressive residual stress and microhardness. Furthermore, severe plastic deformation occurred in the surface layer of the specimen, which refined the grains and increased the density of high- and low-angle grain boundaries. Besides, the results of the fretting test showed that the USR treated specimens had lower wear volume, dissipated energy, and steady-state friction coefficient. The fretting wear resistance increased with the static load and the number of passes. The fretting wear mechanism changed from abrasive wear and severe adhesive wear to slight fatigue wear and abrasive wear owing to the use of the USR treatment. Surface smoothing and hardening are responsible for the improvement in the fretting wear properties of GCr15 steel for USR treatment.