High-Speed Friction Stir Lap Welding of Al Alloys

Abstract

Friction stir lap welding (FSLW) with linear speed of 1 m/min or higher can open up opportunities for industrial implementation. This paper will provide an overview of several challenges and mitigation strategies to produce effective joints between several Al alloys. FSLW of Al alloys at high speed presents challenges including interface hook features and defects at the interface. 5xxx, 6xxx, and 7xxx Al alloys were joined and characterized. Load-bearing capacity in excess of 80% of base material strength has been demonstrated at the welding speed of 2 m/min for 6xxx and 5xxx similar lap joints. The effects of parameters like welding speed, RPM, tool geometry in material flow features, void volume, and hook geometry is investigated and this knowledge base is applied to improve the joint strength of 7xxx lap welds.