On the Residual Stress Field in the Aluminium Alloy FSW Joints

In this study, we evaluated the residual stress field which arose because of a new welding process named 'friction stir welding'. We analysed aluminium alloy butt-welded joints. Both similar and dissimilar joints were considered in 2024-T3 and 6082-T6 aluminium alloys of 0.8 and 3 mm thick. For each joint, the longitudinal and transversal residual stress distributions were obtained in a direction perpendicular to the weld cord. In the thicker dissimilar joints, the longitudinal residual stress distribution present is very similar to the distribution present in traditional welded joints. It presents, in fact, a tensile region near the weld cord, which is balanced by compressive regions away from weld line. On the contrary, other joints present a low compressive stress at the weld toe and a tensile stress state elsewhere. Moreover, the effect of the shoulder geometry on the residual stress field was evaluated on 1.5-mm-thick joints.