Effects of phase difference on the behavior of arc and weld pool in tandem P-GMAW

摘要

Three modes of arc interruption, i.e., background arc interruption, pulse rise arc interruption, and short-circuiting arc interruption are observed during high speed tandem pulsed GMAW of mild steel. The reason for arc interruption is considered to be the over-elongation of background arc caused by the electromagnetic attraction from the peak arc at the other wire. When welding at a phase difference of 0 degrees, no arc interruption occurs because the electromagnetic interaction always takes place between two arcs of identical stiffness. The arc interruption frequency of the leading arc is always higher than that of the trailing one, and increases rapidly with increasing the phase difference. The horizontal components of the arc pressures of the two arcs drive the molten metal to flow towards the middle between the-two wires, resulting in a local bulge there. With increasing the phase difference, the height of the bulged molten metal between the two wires decreases, the weld appearance becomes worse with decreased weld width and increased weld penetration and reinforcement. (C) 2015 Elsevier B.V. All rights reserved.