Microstructures and Properties of Aluminum-Copper Lap-Welded Joints by Cold Metal Transfer Technology

In this paper, 1 mm thick 1060 aluminum sheet and pure copper were joined using AlCu5 filler wire by cold metal transfer (CMT). It was found that it is feasible to join aluminum to copper by this method, and a good wettability and weld appearance was usually obtained. The effect of heat input on the microstructure and tensile shear strength of joints was investigated. The results indicated that a continuous layer of intermetallic compounds (IMCs), i.e., Al4Cu9 (gamma), Al2Cu3 (epsilon), and Al2Cu (theta) was produced in the Cu/weld interface, and the weld metal was composed of alpha-Al solid solutions and Al-Cu eutectic in the grain boundary. Additional heat input promoted the growth of the Al-Cu IMC layer, especially the Al2Cu layer. However, appropriate weld parameters resulted in a thinner IMC layer and improved the joint strength. The maximum load force reached 0.983 kN, and the joint fractured in the heat-affected zone of Al sheet with a ductile fracture mode.