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

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.