Joining of aluminum alloys to galvanized mild steel by the pulsed DE-GMAW with the alternation of droplet transfer

In this study, the welding-brazing process of pulsed double electrode gas metal arc welding (pulsed DE-GMAW) provides a potential method to join dissimilar metals (i.e., joining of aluminum alloys to galvanized mild steel). In order to evaluate the stability of welding process, a mathematical model of the alternation of droplet transfer for the pulsed DE-GMAW is established based on the spring-mass-damper model. The droplet alternative transfer is a free flight with short circuiting transfer mode, which is analyzed and detected during the welding process with double pulsed current. Meanwhile, the pulsed DE-GMAW technology is found to be feasible to join the aluminum alloys to the galvanized mild steel. The variable weldability process of aluminum-galvanized steel could be obtained with a wire by optimizing welding parameters. Microstructures of the intermetallic reaction layer and bonding mechanism of optimized weld-brazed specimens with aluminum ER4043 and ER5356 wires are analyzed and conducted by SEM and tensile test.