When setting up to weld on low carbon steel with GTAW, how should the tungsten be prepared and what polarity should the machine be set to?

When setting up to weld on low carbon steel with GTAW, how should the tungsten be prepared and what polarity should the machine be set to?

• A. Pointed, DCEN
• B. Set 1in (25mm) out of the nozzle, DCEN
• C. Rounded, AC
• D. Even with the nozzle, DCEP

Answer: (A)

For GTAW on low carbon steel, use a pointed tungsten and set the polarity to DC with the electrode negative. A sharp tip concentrates the arc and gives you better control and penetration, which is ideal for steel welds. Running with the electrode negative (DCEN) puts more heat into the workpiece and reduces tungsten erosion, yielding a cleaner weld and longer electrode life. Using a rounded tungsten or alternating current would broaden the heat-affected zone or reduce arc stability on steel, and using electrode positive (DCEP) would overheat the electrode and wear the tungsten faster. Also, keep the tungsten protruding only a short distance from the nozzle, not a full inch, to maintain proper shielding.

For GTAW on low carbon steel, use a pointed tungsten and set the polarity to DC with the electrode negative. A sharp tip concentrates the arc and gives you better control and penetration, which is ideal for steel welds. Running with the electrode negative (DCEN) puts more heat into the workpiece and reduces tungsten erosion, yielding a cleaner weld and longer electrode life. Using a rounded tungsten or alternating current would broaden the heat-affected zone or reduce arc stability on steel, and using electrode positive (DCEP) would overheat the electrode and wear the tungsten faster. Also, keep the tungsten protruding only a short distance from the nozzle, not a full inch, to maintain proper shielding.