Challenges and advances in laser welding of dissimilar light alloys: Al/Mg, Al/Ti, and Mg/Ti alloys

With the growing demand for vehicle weight reduction and the increased application of multimaterial design, it is imperative to address the challenges of welding dissimilar light alloys. This paper presents a review on laser welding of Al/Mg, Al/Ti, and Mg/Ti alloys, with focus on the techniques used to suppress the formation of brittle intermetallic compounds (IMCs) and improve joining mechanism. For Al/Mg joints, studies have shown that the use of structural adhesives, the use of interlayers such as Ce, Ni, Ti, and Fe foils and Zn-Al filler metals, and hybrid adhesive-interlayers could suppress the formation of brittle IMCs and improve joint strength. The formation of brittle IMCs during laser welding of Al/Ti alloys could be minimized by offsetting the laser beam at an appropriate distance towards either the Al or Ti alloy, the use of split-beam laser with appropriate joint design, the use of high welding speed, improving the laser energy distribution, and the use of V-groove with Al-Si filler metals. For Mg/Ti alloys, offsetting the laser beam at an appropriate distance towards the Mg alloy, the use of AZ series Mg alloy-based filler wires, and coating the Ti alloy with Ni were found to facilitate the joint formation and improve the joint strength.