Joining of aluminum alloy and polymer via friction stir lap welding

Sound hybrid joint was achieved with a sufficient mixture of 6061-T6 aluminum (Al) alloy and polyether ether ketone (PEEK) via friction stir lap welding (FSLW) by a tapered thread pin with the triple facets. The larger length ratio between the Al anchor and the rotating pin reached approximately 0.8 at low welding speeds due to the dynamic flow induced by the triple facets. The mechanical interlocking and adhesive bonding attributed to the high-quality joining. Increasing welding speed resulted in the reduction of the adhesion area and the decrease in the size of the Al anchor, deteriorating the mechanical interlocking. A high-quality with the maximum shear bond strength of 20 MPa was achieved through the big Al anchor with a high hardness value. The tapered thread pin with the triple facets has feasible and potential to FSLW of metal and polymer in terms of enhancing mechanical interlocking.