Effects of Ultrasonic Surface Rolling Processing on the Surface Properties of 4Cr13 Stainless Steel

Ultrasonic surface rolling processing (USRP) was applied on 4Cr13 stainless steel. Microstructure observations of the USRP sample surface indicate that the processing can exhibit significant plastic deformation, with a maximum depth of about 253.4 μm, and refine the average surface grain to 0.5 μm. In contrast to the untreated sample, the USRP sample has a minimum surface roughness Ra of 80.1 nm, which is 93.1% lower. Tests of mechanical properties showed a 37.0% increase in the maximum surface microhardness for USRP samples. The residual compressive stress can be as high as-484.4 MPa. It has also been found that USRP can enhance tribological properties under different normal loads. Adhesion oxidation wear dominate in the process of dry-sliding friction based on the surface/interface analysis. The improvement in antifriction and wear resistance is mainly attributed to the reduction in surface roughness and the increase in mechanical properties after USRP treatment.