Effect of ultrasonic surface rolling processing on wear properties of Cr12MoV steel

Ultrasonic surface rolling processing (USRP) with different rolling times (2, 6 and 10 times) was introduced to the Cr12MoV steel. The surface integrity and wear resistance after USRP were investigated. The microstructural features of the surface deformed layer were characterized by some microscopic analysis methods(scanning electron microscopy, X-ray diffraction, X-Ray residual stress analyzer and microhardness analysis). Multifunc-tional friction and wear testing machine was used to test the wear properties of different treated samples along the rolling direction. Results indicate that after two times of USRP, the grain of the plastic deformation layer of the material is significantly refined, moreover, the surface hardness, residual compressive stress and surface roughness were improved. However, the carbon pit produced by carbide exfoliation could not be filled in time, which becomes the source of the layered exfoliation crack and reduced the strengthening effect. With the in-crease of rolling times, the thickness of plastic deformation layer increased and the surface carbide decreased, which is helpful to inhibit the crack initiation and propagation, effectively improving the phenomenon of layered spalling and improve the wear resistance of material.