Surface mechanical property and residual stress stability of shot-peened Mg-8Gd-3Y alloy by in-situ X-ray diffraction

Abstract

Shot peening (SP) treatment is a common surface treatment used to enhance the mechanical properties and stress corrosion resistance of components. However, accurately measuring the mechanical properties of the thin surface deformation layer using conventional techniques is challenging. This study addresses this limitation using an in-situ X-ray diffraction (XRD) test technique in combination with a micro-tensile tester to determine the thin surface layer mechanical properties of the shot-peened Mg-8Gd-8Y (GW83) alloy. The results demonstrated that SP developed a gradient-strengthened layer with ultrafine grains near the surface layer. The minimum domain size was 51 nm using the modified Williamson–Hall method. The yield strength of the strengthened layer was 24% higher than that of the matrix material. The relaxation rule of the surface compressive residual stress (CRS) was explored under tensile–tensile cyclic loading. It was found that the CRS relaxed within five cycles and tended to be relatively stable there after. The relaxation rule was greatly affected by the initial CRS state, external stress amplitude, and cycle numbers.

Keywords

• Mg alloy
• Shot peening
• Mechanical property
• In situ x-ray diffraction
• Residual stress stability