Which polarity is used for welding stainless steel with GTAW?

• A. DCEP
• B. AC
• C. DCEN
• D. ACHF

Answer: (C)

When welding stainless steel with GTAW, the way the heat is distributed in the arc matters for penetration, bead quality, and electrode life. Using direct current with the electrode negative places most of the heat into the workpiece rather than the electrode. This gives deeper, more controllable penetration in stainless steel and helps keep the tungsten cooler, reducing erosion and contamination of the weld.

Alternatives are not ideal for typical stainless welding. AC is mainly used for aluminum and magnesium because it helps clean oxide layers, which stainless steel doesn’t require in the same way. Direct current with the electrode positive pushes more heat into the electrode, increasing tungsten wear and can make arc control harder, without providing a benefit for standard stainless welds.