Dynamic Metal Transfer Behavior in Double-Wire DP-GMAW of Aluminum Alloy Under Different Pulse Phases

Abstract

The effects of pulse phase and pulse stage on the metal transfer characteristics in double-wire double pulse gas metal arc welding (DP-GMAW) of aluminum (Al) alloy were studied using high-speed camera images and current and voltage waveforms. In addition, the effects of various forces on dynamic metal transfer behavior were analyzed under different pulse phases and pulse stages. The results show that the spray transfer mode can be obtained in both the alternating pulse phase (APP) and synchronous pulse phase (SPP). The transfer pattern of the leading and trailing droplets is alternating in the APP, but changes to simultaneous metal transfer in the SPP, mainly owing to influence of the pulse phase on droplet growth. The transfer type is one drop double pulse (ODDP) during the strong pulse stage and one drop triple pulse (ODTP) during the weak pulse stage, regardless of the pulse phase. The pulse phase does, however, affect the Lorentz force between the leading and trailing droplets, causing droplet collision in the SPP, which results in a poorer weld bead appearance compared with in the APP. Finally, the droplet diameter was found to be similar during different pulse phases and pulse stages.