Influence of tool design and welding speed on AA6082 T6–Poly-ether-ether-ketone (PEEK) hybrid joints produced by friction stir welding

Abstract

The transport industry is aiming for a combination of lightweight and high-performance materials; however, their assembly presents certain challenges. In this context, this study explores AA6082 T6 aluminium and poly-ether-ether-ketone (PEEK) hybrid joints manufactured by friction stir welding in a lap configuration. The influence of process parameters, including welding speed (90, 100, and 110 mm/min) and pin characteristics such as diameter, length, and the presence of threads, was investigated through shear strength tests, macro and micro joint analyses, and failure evaluations. The heat input generated in all conditions caused the polymer to plasticize, and its upward flow led to expulsion from the weld bead, creating an irregular surface. The non-threaded pin with a 3 mm length at a welding speed of 110 mm/min generated joints with higher shear resistance (12.9 MPa - 24.6% joint efficiency), attributed to the mechanical interlocking developed by hook formations in the aluminium. In contrast, welding defects related to polymer softening were associated with a reduction in shear strength. Furthermore, a comparison with adhesive bonding indicated a 152% increase in strength when FSW was used.