Friction Stir Welding of Aluminum for Automotive Closure Panel Applications

Friction stir welding (FSW) shows advantages for joining lightweight alloys for automotive applications. In this research, the feasibility of friction stir welding aluminum for an automotive component application was studied. The objective of this research was to improve the Friction Stir Spot Welding (FSSW) technique used to weld an aluminum closure panel (CP). The spot welds were made using the newly designed swing-FSSW technique. In a previous study (unpublished), the panel was welded from the thin to thick side using both an 8 mm and a 10 mm diameter tool. The 10 mm tool passed various fatigue tests; however, the target was to improve performance of the 8 mm tool, especially to increase the number of cycle before the first crack appearance during fatigue testing. In this study fatigue tests and static strength was recorded for weld specimens that were welded from thick-to-thin with an 8 mm diameter tool. Coach peel coupons were welded to help optimize weld parameters and determine weld failure type (failure mode). Panels were welded using a multi-articulate robot and were fatigue tested, using a previously developed technique to 100,000 cycles. Fatigue tests showed improved fatigue life than had been previously achieved with 8 mm tool for thin-to-thick panel welding. Energy consumption for swing-FSSW panels was less than 700 J/weld, thus swing-FSSW can help reduce energy consumption and help contribute to Green Manufacturing.