A Comparison of Resistance Spot Welding with Refill Friction Stir Spot Welding for Automotive Assembly

As the automotive industry increases aluminum us for body panels, traditional welding paradigms are being challenged. Improvements in solid-state joining technologies challenge traditional fusion welding techniques for aluminum assembly. Refill Friction Stir Spot Welding (RFSSW) is spot joining technology that is well-suited for automotive joints in AA6061-T4. A comprehensive analysis was made of eight spot joint configurations of two and three sheet stacks ranging from 2.0 mm to 5.7 mm in thickness. These material thickness combinations are sourced directly from Toyota’s current manufacturing processes, where resistance spot welding (RSW) is used for primary assembly. A comparison of microstructure and mechanical performance of welds from both RSW and RFSSW are evaluated. The microstructure is analyzed via optical microscopy, CT scanning, and microhardness testing. The mechanical properties are quantified through quasi-static tensile and fatigue testing. Surface topography is also quantified.