Influence of shielding gas nozzle design on power density distribution in low-current TIG welding arcs

Shielding gas nozzle diameter variation and its impact on the anodic power distribution of low-current tungsten inert gas arcs were investigated, while maintaining either shielding gas flow rate or flow velocity constant. In addition, the effects of anode surface condition and flow behaviour type (laminar or turbulent) caused by the shielding gas nozzle applied were studied. It was found that arcs of 50 amperes (A) welding current were highly unstable deploying the conditions used, while increasing the arc electrical current to 100 A led to improved arc stability. As found in previous investigations, non-Gaussian distribution profiles occurred at 50 A, even with improved shielding. The power density maxima were found shifted away from the arc axis.