Thoriated tungsten electrodes, were designed for direct current electrode negative (DCEN) or straight polarity applications.
They maintain a sharpened tip configuration during welding which is desirable for the welding of steels, nickel alloys, and most alloys other than aluminum and magnesium.
Thoriated tungsten electrodes are not normally used with AC welding because it is difficult to maintain the balled end (which is necessary with AC welding) without splitting the electrode.
Thorium-Dioxide-Doped Tungsten Electrodes Containing 1.8% - 2.2% THO2.| The most common type of electrode used on carbon and stainless steel.The higher thoria content in the EWTh-2 electrode causes the operating characteristic improvements to be more pronounced than in the lower thoria content EWTh-1.To use Thoriated electrodes for alternating current welding, balling of the end can be accomplished by briefly, and carefully, welding with direct current electrode positive prior to welding with alternating current. During alternating current welding, the balled end does not melt and so emission is not as good as from a liquid ball on an EWP electrode.