Optimization of weld bead shape in double-sided arc welding of AA5182 aluminum sheet

The double-sided arc welding (DSAW) process has been shown to be one of the most effective arc welding techniques for producing aluminum tailor welded blanks. In a DSAW welding system, a plasma arc welding torch (PAW) is mounted above the aluminum sheet and a gas tungsten arc (GTAW) torch mounted below the sheet. The PAW torch is connected to the positive terminal of a square-wave variable polarity power supply and the GTAW torch to the negative terminal. The welding current flows from one torch through the sheet to the other torch. Thereby, simultaneously heating and melting both sides of the sheet and forming a full penetration weld. This unique and novel arc welding process can be used to produce high quality fusion welds between aluminum alloy sheets in butt joint configuration with sufficient cathodic cleaning on both sides at high-speed welding rates. The cost of the system is a fraction of traditional laser welding systems while the severity of welding defects such as undercut, underfill and drop-through can be decreased significantly when DSAW process is used. Complete elimination of these defects has not been reported yet. In this study, therefore, the effects of various DSAW process parameters on the weld bead shape in double-sided arc welding of 1mm thick AA5182 aluminum sheet in the butt joint configuration have been investigated with the goal of optimizing the final weld quality by decreasing the severity of welding defects and surface discontinuities. Specifically, the effects of total arc gap, torch type, and torch offset distance in the welding direction on both cathodic cleaning and final weld bead geometry were investigated. (Abstract shortened by UMI.)...