Effect of Laser Shock Peening on Stresses and Tensile Properties of 7075 Aluminum Alloy Welded Joint

Abstract

After laser shock peening, surface residual stress of welded specimens was acquired using X-ray diffraction (XRD) and the tensile properties were also tested, and the fracture morphology was analyzed by scanning electron microscopy (SEM). Results showed that the effect of laser shock peening on the surface residual stresses of welded joint perpendicular to the welding seam was higher than that parallel to it. The stress value of the crown surface was larger than that of the root surface. The yield strength, ultimate tensile strength, and breaking strength improved by 60%, 32%, and 50%, respectively. Fractography analysis demonstrated that the fracture modes of the peened specimens consisted of aggregated micropores and transgranular fracture. The strengthening mechanism of LSP on 7075 aluminum alloy welded joints is mainly fine-grain strengthening and dislocation strengthening.

Keywords: Laser shock peening, Mechanical properties, Residual stress, Fractography analysis