Role of tool shoulder profile and tool rotational speed on the mechanical performance of friction stir welded Al5083 joints

Abstract In the current work, Al5083 weld joints have been produced by friction stir welding using three different tool shoulder profiles (flat, concave and convex) at three different tool rotational speeds (900 min −1 , 1120 min −1 and 1400 min −1 ) with an objective to investigate the role of tool shoulder profile and welding parameters on the joint quality. The cross sectional microstructural observations revealed the development of perfect weld joint at 900 min −1 and 1120 min −1 with flat and concave shoulder profiles due to the better material flow in the stir zone. Other weld joints revealed the presence of tunneling defect at the bottom of the nugget zone. Hardness measurements of the weld joints showed increased values at 1120 min −1 with concave shoulder. From the impact test data, all the weld joints exhibited similar impact energy compared with the base material except the weld joint produced with concave shoulder at 1120 min −1 . Tensile tests of the weld joints demonstrated better joint strength for the weld joints obtained with both the flat and concave shoulder profiles at 1120 min −1 without losing the ductility similar to that of the base alloy.