Study on pulsed laser welding of AZ31B Mg and 6061 Al alloys using Cu interlayer

Abstract

This study aims to investigate Nd:YAG laser welding of dissimilarMg/Al joints using Cu interlayer. Welding processing, microstructure and the corrosion properties of laser-weldedMg/Al joints with Cu interlayer were discussed. According to the results, the pulse width is the most important influence on weld formation of dissimilarMg/Al joints, followed by laser power and welding speed. Selected optimization process parameters of 1mmAZ31B/6061 lap welding are: Laser power is 6 KW, laser pulse width is 7.5 ms, velocity is 1.2mms-1. There is no obvious pore and cracks in theMg/Al joint with Cu interlayer. The Mg-Al-Cu compounds are introduced to the Mg-Al binary system and then the microstructure of the fusion zone is optimized and improved. The IMCs are mainly consisted of Mg17Al12, Al3Mg2 and Al6CuMg4. The plastic of (Al6Cu)Mg4 is better than that ofMg17Al12, Al3Mg2 according to the calculation. Model of mechanism of interfacial reaction layer is established. Because of the existence of Cu, the reaction of Mg, Al was depressed and the generation of MgAl compounds was decreased. The corrosion resistance of alloys in different conditions decreased in the following order: 6061 Al>the weld beam>AZ31B Mg.