Effect of the tool penetration depth in Friction Stir Spot Welding (FSSW) of dissimilar aluminum alloys

In the last years Friction Stir Welding has produced a big impact on several industries due to its advantages. Particularly, automotive industry has developed a variant of the original process named Friction Stir Spot Welding (FSSW), having a strong influence on welding of thin sheets of aluminum alloys and dissimilar materials. Nevertheless, the knowledge about the influence of welding procedure on joint characteristics is scarce, mainly for dissimilar materials. The aim of this work was to study the effect of the tool penetration depth during welding, as well as, the relative position of the materials used in the superimposed joints, when AA5052-AA6063 sheets samples were welded. Tool penetration depths between 0.05 and 1.25 mm were analyzed, for both materials positions. Macrostructural and dimension characterization, microhardness profiles and Peel tests (PT) were done for different conditions. The fracture loads in PT increased with the tool penetration depth for both material positions, being higher when AA6063 was the upper material. However, the tool penetration depth has a limit in the increasing of fracture load, for which the fracture mechanism changes from interfacial to circumferential. (C) 2015 The Authors. Published by Elsevier Ltd.