Friction Stir Welding Process of Aluminum-lithium Alloy 2195

Abstract

Friction stir welding is solid state welding and involves heating the metal with a suitable amount of pressure so that homogeneous and complete microstructural welding is possible without melting of the parts to be joined. The process uses a rotating tool with a profiled pin that penetrates the parts to be joined; the tool then starts to travel along the join line. By keeping the tool rotating and moving it along the join line to be welded, the softened material due to the frictional heat is stirred and mixed together by the rotating pin forming a weld in solid state without melting. Frictional heat generated by rotation of the tool due to the high compressive pressure and shearing action of the shoulder along the joint line causes a softened zone of material without melting. Localized severe deformation around the tool results in refinement of the microstructure and the material flow produces coalescence and formation of a weld. FSW provides superior welding over conventional fusion welding and is preferred for joining of Al-Li alloys. The present work is to investigate was to study the effect of friction stir welding parameters on mechanical and microstructural properties of AA2195-T0 and T8. Since FSW is both a deformation and a thermal process, temperature distribution during FSW is measured. The microstructure and mechanical properties of welded joint were investigated for different friction stir welding conditions. This paper describes the results of an experimental study to investigate the mechanical and microstructure evolution of AA2195 friction stir welded joint. The optimum welding condition is also provided for different heat treated AA2195 alloys.