Achieving high property friction stir welded aluminium/copper lap joint at low heat input

Abstract

Aluminium and copper plates with 3 mm thickness were successfully friction stir lap welded at a lower rotation rate of 600 rev min⁻¹ using a larger pin 8 mm in diameter. Good metallurgical bonding on the Al/Cuinterface was achieved due to the formation of a thin, continuous and uniform Al–Cu intermetallic compound layer. Furthermore, many Cu particles consisting of pure Cu and intermetallic compound layers were generated at the lower part of the nugget zone, forming a composite structure with increased hardness. A lower rotation rate resulted in a decrease in annealing softening in the heat affected zone (HAZ), and a larger diameter pin increased the Al–Cu bonding area. These factors resulted in that the friction stir welded lap joint exhibited a high failure load of 2680 N with failure in the HAZ on the aluminium side.