Dissimilar Cu/Al welding by high power blue laser for E-mobility

The interest in the joining of Cu and Al alloys for some industrial sectors, such as the electrical mobility one, has been growing in recent years, despite their difficulties in laser based processing. Welding by means of lasers operating in the near-infrared (n-IR) field (typically 1060 nm) suffers from the low absorption coefficient of highly reflective materials, making joining these alloys difficult and inefficient. Recently, new laser sources have appeared on the market, with emission at 450 nm (indicated as blue radiation). Absorptivity coefficient of blue laser is significantly higher than n-IR laser in the case of Cu. The present work explores the use of a high-power blue laser source, lasers having enough power to be adopted in real industrial environments, for dissimilar welding of thin Cu and Al sheets. The evolution of the shape and size of the welded beads obtained by employing different combinations of laser power (2-3 KW) and welding speed (10-100 mm/s) values was evaluated. Thereafter, compositional and microstructural investigation, as well as mechanical tests, were performed to evaluate the quality of the joints. The selected process conditions promoted the generation of satisfactory welded beads, exhibiting good strength thanks to the efficient mixing of Cu and Al.