Abstract: A method for high efficiency and low heat input, pulsed double-electrode gas metal arc welding(DE-GMAW), joining of aluminium to steel is presented. In order to achieve the droplet steadily transfer at the process of welding, analyzing the bypass arc influence factors of the current density. The electromagnetic force action mechanism of the Pulsed DE-GMAW droplet transfer is established. Under the circumstance of the base metal is pulse current, studying on designing three forms of the bypass waveform and the base metal matching forms for constant current, alternate pulse current and synchronous pulse current, respectively. Use a high speed camera to capture the droplet transfer image for experiment comparison and verification. The results show that the different welding current waveform and the matching form would lead to the change of the forces exerted on the welding droplet, thus the welding process stability and weld quality is found changing. The pulsed DE-GMAW welding process is stability, the droplet transfer is uniform and the weld shape is smooth and beautiful by using of synchronous pulse current.

Key words: current waveform, droplet forces analysis, pulsed double-electrode gas metal arc welding, welding-brazing joint between aluminum and steel