Surface Residual Stress in Aluminum-Lithium Alloy Shot-Peened at Different Shot Peening Intensities

The aluminum-lithium alloy was surface hardened at different shot peening intensities, and then the residual stresses in the surface and near-surface layers were analyzed by X-ray diffraction and the hole-drilling strain-gage method respectively. The results show that the surface residual stresses in 90° direction (parallel to moving direction of the nozzle) of the specimens treated at different shot peening intensities were higher than those in 0° direction (perpendicular to moving direction of the nozzle), and the integral breadth of the diffraction peak in 90° direction was larger than that in 0° direction, indicating that more micro-strains were generated in 90° direction of the specimen after shot peening. With the increase of the depth, the residual compressive stress in the near-surface layer of the specimen first increased then decreased, and finally approached zero. The residual stresses induced after treated at a relatively strong shot peening intensity at the surface and within 0.15 mm below the surface of the specimen were lower than those induced at a relatively weak intensity, while the maximum residual compressive stresses and the depth of the maximum residual compressive stress and the residual compressive stress field were larger than those at a relatively weak intensity.