What is the current used for welding stainless steel with GTAW?

• A. DCEP
• B. AC
• C. DCEN
• D. ACHF

Answer: (C)

Direct current electrode negative (DCEN) is used for welding stainless steel with GTAW because it concentrates heat in the workpiece, giving better penetration and reducing tungsten contamination in the weld. With the electrode negative, electrons flow from the electrode to the work, so the work piece heats more than the electrode, making it easier to control weld geometry on stainless steel.

Using electrode positive (DCEP) would heat the electrode more and erode the tungsten faster, increasing the risk of tungsten inclusions in the weld and making control more difficult. Alternating current (AC) is mainly used for cleaning oxide layers on materials like aluminum; for stainless steel, DCEN is the standard approach for most situations.