Effects of bypass current on the stability of weld pool during double sided arc welding

•Proposed stabilising of the DSAW process with bypass current.•Pressure distribution of MIG arc and MIG–TIG coupling arc were measured.•The application of bypass current eliminates the weld depression in DSAW.•Force module of weld pool was established and forces on weld pool were analysed. The arc behaviour and flow patterns in the weld pool were monitored with a high speed camera and the pressure distribution of the MIG–TIG coupling arc was measured through a specially devised method involving a micro-orifice for quick ignition. The bypass current changed the geometry of the weld pool in such a way that the acting forces remained in equilibrium stabilising the pool, the weld depression was eliminated and the pressure at the arc centre decreased by a factor 4. The overall welding efficiency increased as much as the quality of the welds.