Effect of laser welding strategy for reducing intermetallic compound formation and residual stress

Abstract

Reductions in automobile weight and carbon dioxide emission are critical for the further development of the automobile industry. Aluminum is a lightweight material that can replace copper in automobile electronic equipment; therefore, laser welding of aluminum and copper is a subject of extensive research. This study investigates the influence of the laser strategy on the laser welding of aluminum and copper while preventing the formation of brittle Al–Cu intermetallic compounds. Aluminum and copper plates with a length of 20 mm and thickness of 0.3 and 1 mm, respectively, are used for the experiment. A continuous-wave laser with a power of 500 W and a spot beam radius of 150 μm is employed to irradiate the aluminum surface at different scan speeds. An electroless-plated nickel layer is used as a buffer between aluminum and copper, and the experimental results show that it can prevent copper surface damage and the formation of Al–Cu compounds during laser welding. In addition, the simulation and experimental results reveal that the residual thermal stress after laser welding can be reduced by heat treatment at different temperatures prior to laser irradiation.