Effects of parameters on friction stir welding process of AA 7075 aluminum alloy: mechanical and microstructural assessments

Abstract

The effect of tool rotation speed and welding speed on the microstructural and mechanical properties of AA 7075-T651 welded plates produced using friction stir welding is the research subject of this study. A basin-shaped stir zone characterized all friction stir welded joints' microstructures. The fracture location following the tensile test was found to be outside the stir zone for each welded joint. All welded joints were subjected to a 90°root bending test. The tests were terminated before each welded joint could reach the 90°bend angle in the stir zone. The stir zone of each welded joint was characterized by the fine and equiaxed grains with the effect of dynamic recrystallization. In addition, intermetallic particles were also detected to occur in the weld joint. Among the nine welded joints, the welded joint with the highest ultimate tensile strength of 382 MPa was produced with a tool rotation speed of 400 min À 1 and a welding speed of 80 mm min À 1 . The highest welding efficiency of 71 % was obtained with the welding process parameters of 400 min À 1 tool rotational speed and 80 mm min À 1 welding speed. Increasing tool rotation speed caused the grain size to be coarser.