High-Speed Welding of Steel Sheets by the Tandem Pulsed Gas Metal Arc Welding System †

Abstract

In tandem gas metal arc (GMA) welding, it is important to prevent adverse effects caused by electromagnetic interference between the two adjacent arcs to create good metal transfer. In the tandem pulsed GMA welding system, newly developed by the authors, pulse peak currents are fed simultaneously to the leading and trailing electrodes in principle and a unique pulse timing control is employed in which the end of a pulse peak current for the trailing wire is delayed by 0.5 ms from that for the leading wire to prevent the arc extinguishing By using the tandem pulsed GMA welding system, the effects of the inter-wire distance, inclination angle and welding current (wire feed rate) ratio between the two wires have been investigated to study the essential requirements for the welding torch configuration and the allocation of welding currents to obtain sound weld beads with the absence of undercut and humping in the high speed welding of steel sheets. When the welding speed was 3 m/min, a sound weld bead with uniform width was obtained with the trailing wire set at 9-degree push angle regardless of the inclination angle of the leading wire. The inter-wire distance greatly affected the weld bead formation in high speed welding. That is, the maximum welding speed was improved with the proper inter-wire distance in the range 9 to 12 mm. In the proper range of welding current ratio, IT/IL=0.31 to 0.5, the maximum welding speed achieved was 4 to 4.5 m/min, which is 275% higher at the maximum when compared with single wire pulsed GMA welding (at a maximum welding speed of 1.2 m/min).