Microstructure and mechanical properties of joints of friction stir welding 7055 Al alloys by spray formation

An industrial large-scale 7055 Al alloy billet was prepared by fully automatic controlled reciprocating spray formation technology, and the as-deposited aluminum alloy was joined by friction stir welding (FSW). The appearance, microstructure and mechanical properties of the joints were investigated by many kinds of experimental means. The results show that, the FSW joint which is 4 mm in thickness presents excellent appearance, defect-free, less distortion. The characteristics of the three distinct zones can be clearly identified, the joint tensile strength of 475 MPa reaches up to 77% of the base material's and that is much higher than that of the conventional fusion welding joints. Fracture region locates at the heat-affected zone. After the T6 heat treatment, the tensile strength decreases, but the elongation increases from 2.58% to 6.42%.