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. •Ultrafine grains surface layer with strong (110) and (211) texture is produced by ultrasonic surface rolling.•Surface roughness is reduced drastically and surface microhardness is improved by 20%.•Friction coefficient and wear rate are decreased up to 10–14.3% and 25% respectively.•The corrosion resistance is enhanced by ultrafine grains surface layer.