Effects of Welding Current on Metal Transfer and Weld Pool Dynamics in Gas Metal Arc Welding

Abstract

In gas metal arc welding (GMAW), current is one of the most important factors affecting the mode of metal transfer and subsequently the weld quality. Recently, a new technology using pulsed currents has been employed to achieve the one droplet per pulse (ODPP) metal transfer mode with the advantages of low average currents, a stable and controllable droplet generation, and reduced spatter. In this paper, the comprehensive model recently developed by the authors was used to study the influences of different current profiles on the droplet formation, metal transfer, and weld pool dynamics in GMA, welding. Five types of welding currents were studied, including two constant currents and three waveform currents. In each type, the transient temperature and velocity distributions of the arc plasma and the molten metal, and the shapes of the droplet and the weld pool were calculated. The results showed that a higher electromagnetic force was generated at a higher current and becomes the dominant factor that detaches the droplet from the electrode tip. A smaller droplet size and a higher droplet frequency were obtained for a higher current. The model has demonstrated that a stable ODPP metal transfer mode can be achieved by choosing a current with proper waveform for given welding conditions.