Gas Tungsten Arc Welding (GTAW) WELD 250 Practice Test

Direct-current electrode-positive (DCEP) GTAW delivers more heat into the workpiece, increasing the heat input at the weld. Metals with very high melting points—refractory metals like tungsten, molybdenum, niobium, and tantalum—need that extra heat to melt and fuse properly, so DCEP GTAW is usually used for them. Other common welding metals (steel, stainless steel, chromium-containing steels, aluminum, etc.) are typically welded with DCEN or AC, where the heat distribution and arc characteristics suit those materials better. The trade-off with DCEP is quicker erosion of the tungsten electrode and more electrode wear, which is acceptable here because the goal is to achieve sufficient heat for these high-melting-point metals.