Effect of composition of Al-Si welding wires on welded joint characteristics of copper and aluminum by CMT welding

Abstract

Cold metal transfer (CMT) welding was employed to weld the dissimilar metallic sheets of T2 and 1060 aluminum. S301,ER4043 and ER4047 welding wires were used as filler materials, respectively. The effects of composition of Al-Si welding wires on the characteristics of Cu-Al welded joints obtained by using suitable CMT welding parameters were studied. The results show that the three welded joints are composed of weld zone, bonding zone, fusion zone, and the thick interface compounds are generated at the bonding zone near the copper sheets. The microstructure of the three bonding zones is mainly (α-Al+CuAl2) eutectic and CuAl2 intermetallics. Moreover, the massive Si phases are found at the bonding zones of the welded joint that produced by using ER4047 welding wire with 12.0% Si. These results indicate that Si element in the welding wires can restrain the growth of the interface compounds in the weld near the copper sheet, and the morphology of the compounds also can be changed by Si element as changing their contents in welding wires. The microhardness peak zones are formed in the copper side of the joint interface because of these interface compounds.