Friction Stir Welding of Cast Aluminum Alloys

The mechanical properties and structure of the joints of cast aluminum alloys made by friction stir welding (FSW) are studied. The processes of intense plastic deformation during FSW influence the formation of the weld microstructure, on which its strength properties depend; however, the determining factor is represented by the specific temperature–time FSW conditions. The study of the structure of the weld core revealed a special layered metal structure consisting of recrystallized grains separated by high-angle boundaries. The average grain size in the stir zone is shown not to depend on the average grain size in the initial casting: it is determined by the FSW parameters. A fully recrystallized structure with an average grain size of 3.9–5.3 μm is found to form in the weld core during FSW of cast aluminum alloys. The strength coefficients of the FSW welded joints of VAL10, AL19, and VAL16 alloys are 79.2, 81.3, and 96.7%, respectively.