Which polarity is preferred for welding stainless steel with TIG?

• A. AC
• B. DCEN
• C. DCEP
• D. DCOP

Answer: (B)

Direct current with the electrode negative is preferred for TIG welding stainless steel. This setup concentrates heat into the workpiece, giving deeper penetration and better fusion with stainless, while keeping the tungsten electrode cooler and reducing wear. Stainless doesn’t need the oxide-cleaning action provided by alternating current the way aluminum does, so AC isn’t advantageous here. Using electrode positive would send more heat into the electrode and reduce penetration, and alternating current is generally unnecessary for stainless unless you have a very specific thin-section or cleaning requirement. So, DCEN gives stable arc, good control, and solid penetration for typical stainless TIG welds.