Evaluation of Weld Parameters on the Mechanical Properties of Friction Stir Welded AA7075-T6 Lap Joints

Friction stir welding (FSW) is a simple technique that can develop strong joints in aluminum alloys that are otherwise difficult to join by conventional arc welding processes. AA7075 is increasingly migrating from aerospace to automotive applications to meet new fuel efficiency requirements. There is a need to develop the FSW process to ensure joints are fabricated quickly at low cost. The geometry of the FSW tool is a parameter that plays a major role in both the quality of the weld and the speed at which it can be made. This study compares three tool designs for lap FSW of 2mm thick sheets of AA7075-T6. Travel speeds from 125 to 250 mm/min are compared in terms of joint mechanical properties, while tool rotation speeds are kept constant at 1120 rpm. Microstructures, hardness profiles, and tensile strengths were measured to derive suitable parameters for automotive applications.