Effect of Welding Current on Tensile Behaviour and Weld Morphology of Al/Mg Dissimilar Alloy Joint Using Cold Metal Transfer Welding

Cold metal transfer (CMT) welding is widely used to weld dissimilar metals. While joining dissimilar metal there is a chance of formation of intermetallic phase so it can reduce the strength of weldment. CMT welding has the potential to control heat input and thereby minimizes the intermetallic compound formation which improves the quality of the weld. There is a requirement to weld dissimilar alloys, such as steel, aluminium and magnesium, in numerous applications, such as the automotive and aerospace industries. In CMT welding, the motion of wire controls the overall process in which retraction mechanism during short circuit helps to detach droplet from molten weld pool so that the metal can transfer into the weld pool without electromagnetic force. In this way, the heat input and spatter can be controlled thereby improving the joint strength. This paper investigates the impact of welding current on tensile behaviour and weld morphology. The maximum value of tensile strength is 36 MPa obtained at a welding current of 140 A. As the current exceeds 140 A there is the formation of an intermetallic compound which is responsible for poor fusion, while a low welding current results in incomplete penetration.