Influence of probe length on the formation of an interface in friction stir welded T-lap joints

The dissimilar aluminum alloy of the T-lap joints between 7075 and 5083 was Friction Stir Welded (FSW). The attention was focused on the influence of probe length on the formation of a bonding interface between skin and stringer. The bonding interface of the joints was clarified by using skin and stringer tensile tests. Both the morphology and bonding strength of the interface were significantly influenced by the pin length. The hook defects could be eliminated by applying the short probe length but led to enhance the bonding line defect. The kissing bond defects at the two corner fillets seemed to be uneliminable and unaffected by the probe lengths. A suitable pin length was proposed to maximize joint efficiency for both the skin and stringer tests.