Effects of bypass current on arc characteristics and metal transfer behaviour during MIG–TIG double sided arc welding

Abstract

Experiments were carried out on 2mm thick 304 stainless steel to verify the feasibility of Bypass Current Double Sided Arc Welding (BC-DSAW) for high-speed welding of thin plates. A high-speed camera was utilized to monitor the metal transfer process and the arc behaviour. The current density distribution of the MIG–TIG coupling arc was measured with the probe method. The bypass current increased the melting efficiency of the filler wire and reduced the heat input of the base metal; the current density at the arc centre was decreased by 30% with bypass current added. Owing to the preheating effect of the bypass arc on the filler wire, the metal transfer mode was altered from short circuiting transfer to globular transfer and the droplet growing time was shortened to increase the transfer frequency by 50%.