Which types of current are used with GTAW?

• A. AC; DCEN; DCEP
• B. DCEN; DCEP; AC
• C. DCEN; AC
• D. DCEP; AC

Answer: (B)

GTAW can be run on both alternating current and direct current in either polarity, giving three practical current modes to choose from. Alternating current is used especially for metals with oxide layers, like aluminum, because the current reversals help clean the surface and keep the arc stable. When using direct current, you have electrode negative (DCEN) and electrode positive (DCEP). DCEN focuses more heat into the workpiece, producing deeper penetration and a strong weld on steels and stainless. DCEP puts more heat into the electrode, which can be useful for controlling heat input on certain metals or thin sections and can affect arc behavior and tungsten wear. Since GTAW supports all three modes, the best answer lists AC, DCEN, and DCEP.