Effect of Interface Morphology on the Mechanical Properties of Friction Stir Welded T-lap Joints of 7075/5083 Aluminum Alloys

T-lap joints are widely utilized in connecting various structural elements owing to their efficient application. Typically, the mechanical properties of the joints are critical in maintaining an effective connection. In this study, we examined the role of the interface morphology in failure behavior of the dissimilar friction stir welded (FSWed) T-lap joints of 7075/5083 aluminum alloys. The experimental results verified that the morphology of interface of the joints was sensitive to the number of welding passes and tool offset. Additionally, the kissing bonds (KBs) were minimized significantly when the tool offset was combined with the double-pass welding. Furthermore, both the tensile and fatigue strengths of the joints were extremely sensitive to the interface geometry. We performed a quantitative analysis using a simplified fracture mechanics model and finite element method to clarify the failure behavior of the FSWed T-lap joints that must be optimized in terms of both the size and geometry of the KBs by altering the welding conditions.