Droplet Transfer Characteristics of Aluminum Alloy Double‐Wire Variable‐Polarity Single‐ and Double‐Pulsed Gas Metal Arc Welding

ABSTRACT

The aluminum (Al) alloy double‐wire variable‐polarity double‐pulsed gas metal arc welding (DW‐VP‐DP‐GMAW) process integrates the advantages of VP and DP welding based on the DW‐GMAW process, thereby increasing the welding deposition rate and efficiency while controlling the heat input. Droplet transfer is a critical process that determines the weld formation quality. To elucidate the influences of the electrode negative (EN) ratio and DP on droplet transfer, a droplet force model was established based on the static force balance model (SFBM). The droplet transfer process was observed using high‐speed photography, and characteristic parameters, including droplet detachment time, transfer time, droplet size, and the probability of two droplets per pulse (TDPP), were systematically analyzed. The results showed that the introduction of direct current electrode negative (DCEN) polarity could eliminate explosive transfer and significantly reduce the probability of TDPP. With the increase in the EN ratio, the droplet diameter increased from 1.2 to 2.0 mm, the detachment time prolonged from 4 to 7 ms, and the transfer time increased from approximately 5 to 10.5 ms. DP reduced the amount of molten metal by decreasing the wire feed speed (15%–20% lower than that of a single pulse (SP)), which further optimized the stability of droplet transfer and reduced the probability of TDPP by more than 30%.