Friction Self Piercing Riveting of Aluminum Alloy AA6061 T6 to Magnesium Alloy AZ31B

Abstract

Implementation of lightweight lowductility materials such as aluminum alloys, magnesium alloys and composite materials has become urgently needed for automotive manufacturers to improve the competitiveness of their products. However, hybrid use of these materials poses big challenges to traditional joining process. Selfpiercing riveting (SPR) is currently the most popular technique for joining dissimilar materials and has been widely used in joining allaluminum and multimaterial vehicle bodies. However, in riveting magnesium alloys, cracks always occur for its low ductility. In this paper, a hybrid joining process named friction selfpiercing riveting (FSPR), which combines mechanical joining mechanism of SPR with solidstate joining mechanism of friction stir spot welding (FSSW) by making rivet rotating at high speed in riveting process, was proposed aiming at joining the lowductility materials. The effectiveness of the FSPR process was validated via riveting 1 mm thick AA6061T6 and 2 mm thick AZ31B. The results showed that the FSPR process could significantly improve the rivetability of magnesium alloys, and greatly increase the joint strength, comparing with the traditional SPR process.