Mechanical and Bending Characteristics of Dissimilar Friction Stir Welded AA 2024 T6 - AA 7075 T6 Butt Joints

Abstract

Friction stir welding has proved as one of the best solid state joining method for materials such as aluminium and magnesium. Some of the aluminium alloys which are not weldable (Al-Cu, Al-Zn-Mg alloys) by fusion welding techniques, and or produce defects and reduce the mechanical properties, could be welded using friction stir welding (FSW) successfully with excellent joint efficiencies. However, the process parameters exert significantly on the properties of weldment and therefore needs to be investigated thoroughly.

In this study, friction stir welding of dissimilar aluminium alloys AA2024&AA7075 are selected. The welding process were conducted on varying the welding process parameters such as Tool rotation speed (rpm), Welding speed (mm/min), Downward force (kN) and Tool pin profiles. The mechanical properties and bending behavior on welded plates were studied and compared with the base metal. Experiments were performed with rotational speeds 600, 700, 800 and 900 rpm at six welding speeds i.e. 20, 30, 40, 50, 60 and 70mm/min keeping constant axial load 2.5kN and tool tilt angle 0°. It was found that there is no defect concentration for the tool speed rotation of 600 rpm, welding speed 30 mm/min and 2.5 kN downward force. Tensile and bend test values were also reported.