Microstructure and surface properties of 17-4PH stainless steel by ultrasonic surface rolling technology

Ultrasonic surface rolling (USR) is a surface modification method to generate a nanostructured surface layer with highly improved mechanical behaviors. In this paper, the USR technology was used to improve the surface performance of 17-4PH stainless steel and the microstructure and mechanical properties of USR-treated17-4PH stainless steel were investigated in detail. The microstructural features were investigated by X-ray diffraction and scanning electron microscopy. A certain thickness deformation layer consisted of the nanoscaled metal grains was obtained on the surface of 17-4PH stainless steel by the USR technology. And the surface properties of USR-treated 17-4PH stainless steel were improved significantly, such as the surface roughness, microhardness and the residual compressive stress. In addition, the friction-wear performance test and potentiodynamic polarization experiment were conducted for USR-treated 17-4PH steel. Based on the experimental results, the wear and corrosion resistance of the USR-treated specimens were both improved markedly.