Impact of tool offset and friction stir welding speed on interface morphology of a dissimilar T-lap joints

The dissimilar aluminum alloys of 5083 and 6061 were friction stir welded via T-lap configuration. The impact of the tool offsets and the tool moving velocity on the interface geometry and the bonding strength of the joints was investigated. The experimental results showed that the interface morphology was sensitive to both the tool offsets and welding rates. The hook defects were easily formed at low welding rate of 150 mm/min. The kissing bonds were ineliminable by both the tool offset and the tool speed. The joint strength was improved due to the offsetting pin tool toward both the retreating side and advancing side with a distance of 0.3 mm. The effect of the tool offset on the joint tensile strength was more remarkable than that of welding rate. The interface formation and fracture behavior of the joints were also revealed to clarify these findings.