Investigation of friction stir welded jonts of 1050 aluminum alloy by inserting Cu foils

Aluminum alloys are used in many industries because of its high strength to weight ratio. Due to many problems of fusion welding of aluminum alloys, in the past decade, much attention of scientists and craftsman has been directed towards friction stir welding (FSW) as a solid-state welding process. In this study, microstructural evolution and mechanical properties of butt friction stir welded wrought 1050 aluminium alloy by inserting pure copper foil has been studied. Friction stir welding was conducted at a tool traverse speed of 25 mmmin−1 and a rotational speed of 1200, 1600 and 2000 rpm. The mechanical properties in forms of tensile tests showed that the strength of base metal (initial = 137MPa) diminished about 45% to 73MPa during friction stir welding without Cu foil in the stir zone after friction stir welding. Formation of intermetallic compound particles such as Cu9Al4 and Al2Cu, between aluminium matrix and Cu foil, increased strength of the stir zone. Furthermore, fractography characterization revealed that, Fracture place of weld joints without foil and with foil occurred at advancing side and retreating side in the stir zone respectively. This is related to aggregation of intermetallic compound particles in retreating side. Finally, the maximum UTS of joint increased to 98MPa (about 25%) that achieved in specimen with Cu foil with rotational speed of 2000 rpm.

Keywords:

Friction Stir Welding , 1050 Aluminum Alloy , Copper Foil , intermetallic compound