TWI

Dissimilar lap joints were fabricated in various aluminium alloys by conventional friction stir welding (FSW) and a hybrid FSW process involving two adhesive systems, and the influence of thermal degradation of adhesive on the microstructure and mechanical properties of the joints was investigated. The grades studied were AA 6111-T4 (Al, 0.79%Mg, 0.67%Si, 0.81%Cu), AA 5083 SPF (Al, 4.72%Mg, 0.87%Mn) and AA 6061-T6 (Al, 0.81%Mg, 0.56%Si, 0.2%Cu). The adhesive systems comprised one part heat cured epoxy (Teroson 5089) and two part room temperature cured methacrylate (H8000). FSW was performed using an "MX Triflute" tool with a scroll-convex design feature. Microstructure was observed by optical microscopy and SEM. Mechanical properties were characterised by single lap shear tests and single lap shear fatigue testing. Issues discussed include the relationship between hooking height, joint mechanical strength and heat input and the influence of process parameters on adhesive thermal degradation.

12th International Symposium, 26-28 Jun 2018, Session 3A: Techniques I, Paper 01