Welding characteristics of AZ31B magnesium alloy using DC-PMIG welding
(Key Laboratory of Liaoning Advanced Welding and Joining Technology, School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024, China)
Abstract: Direct current pulsed metal inert-gas (DC-PMIG) welding was carried out on AZ31B magnesium alloy to obtain continuous welding joints of 3 mm and 8 mm thickness with 1.6 mm diameter of filler wire. The behavior and mechanism of metal transfer, the parameter ranges of stable welding process, the microstructure and mechanical properties of magnesium alloy were investigated. The results show that the metal transfer form of magnesium alloy using DC-PMIG welding is realized in modes of globular transfer, projected transfer and spray transfer. Welding spatter with a large size will be produced in the mode of globular transfer, and high-quality joints with few spatters can be obtained in the mode of projected transfer and spray transfer when the linear energy of filler wire is 242-271 J/cm, droplet diameter is 1.6-0.9 mm and transition frequency is 30-69 Hz. The average ultimate tensile strength of weld beads is 94.2% of that of base metals.
Key words: AZ31B magnesium alloy; DC-PMIG welding; metal transfer; welding spatter