Arc characteristic evaluation of the double-electrode GTAW process using high current values

This work presents new research results from double-electrode gas tungsten arc welding, a process variant that was developed with the aim of improving productivity and welding speed. A welding torch specially constructed for research was used with total current in the range of 200-600 A. Tests using a high-speed camera were conducted in order to characterize the arc morphology at different distances between the electrodes. It could be seen that the morphology of the arc and the voltage drop in each electrode change significantly with the increase in the welding speed, especially when there is a larger clearance distance between electrodes. The resulting arc presented bigger asymmetry as the welding speed was increased. Bead-on-plate tests were performed in order to evaluate their susceptibility to humping defects. The results showed that in comparison with the conventional GTAW, the double-electrode process enables a considerable increase in the maximum speed, without defects-taking into consideration the total applied current. This shows that this new process has great potential for expanding the range of gas tungsten arc welding in high-productivity welding applications.