Influence of Galvanized Coatings on Abrasion Circle Friction Stir Spot Welding Aluminium to Steel for Automotive Applications

It has previously been shown that dissimilar Al-alloy and un-coated steel automotive sheets can be successfully welded with a cycle time of less < 1 s using a novel solid state joining approach; Abrasion Circle Friction Stir Spot Welding (ABC-FSSW). The ABC-FSSW technique provides an effective strategy for exposing a larger clean steel surface during welding than conventional FSSW, allowing high failure energy joints to be produced. In this study the influence of different steel zinc coatings on the viability of the ABC-FSSW process has been systematically investigated - focusing on the effect on the process window, weld temperatures, and joint performance. The effect of a galvanised coating on the weld formation, zinc dispersal in the joint, and interface intermetallic reaction behaviour are discussed.