Study on the morphology and mechanical properties of dissimilar Al/Al-Li alloy T-joints by friction stir welding

Friction stir welding is an emerging solid-state joining technology. With the advantages of small post-weld deformation and high connection performance, it is widely used in the aerospace field. In this paper, the FSW welding process of 7055-T61 Al and 2197-T8 Al-Li dissimilar T-shaped stiffened panel was investigated. The purpose of this paper is to analyze the influence of tool shoulder structure and welding parameters on the morphology and mechanical properties of T-joints. It is found that compared with the shoulder inner concave surface without spiral, the weld defects of shoulder inner concave surface with spiral are less. When the welding speed v is 60 mm/min, the rotation speed w is 350 r/min and the plunge depth h is 0.21 mm, the transverse tensile strength of T-joint is 408 MPa, which reaches respectively 68.0% and 71.6% of the base materials 7055-T61 and 2197-T8. It shows that the welding quality of T-joints is better when it is implemented under the optimal combination of welding process parameters.