Suppression of weld-bead defects and increase in the critical welding speed during high-speed arc welding

It is of great practical significance to improve welding production efficiency by modifying conventional gas metal arc welding (GMAW) and increasing welding speed. In this study, an experimental system was developed to implement double-electrode gas metal arc welding (DE-GMAW) and to conduct high-speed arc welding experiments. The geometric parameters for assembling two welding torches were optimized according to the weld-bead quality in DE-GMAW experiments. Based on the measured values of the wire current I, base metal current I _bm, and bypass current I_bp, their relationship, i.e. I is the sum of I_bm and I_bp, was validated, and the scheme of DE-GMAW was realized. By means of adjusting the relative levels of the three current components, weld-bead defects such as humping and/or undercut occurring in high-speed welding can be suppressed and good weld-bead formation can be achieved. Compared with conventional GMAW, DE-GMAW can be operated at much higher welding speed without weld-bead defects occurring. The critical welding speed in DE-GMAW is increased by 28.3-80.0 per cent under the conditions employed in the experiments.