Why is DC+ polarity not commonly used in GTAW?

Why is DC+ polarity not commonly used in GTAW?

• A. Overheating of tungsten can occur
• B. It increases shielding gas consumption
• C. It reduces arc stability
• D. It causes porosity

Answer: (A)

In GTAW, polarity changes where most of the arc heat goes. With the electrode positive, the arc concentrates heat into the tungsten electrode itself. The tungsten is non‑consumable and isn’t meant to absorb heavy heat, so using this polarity causes the electrode to overheat and wear quickly, and can even lead to tungsten contamination in the weld. Keeping the tungsten cool and the arc stable is essential in GTAW, so DC+ is not commonly used. Shielding gas flow, porosity, and arc stability are influenced by other factors like gas delivery and cleanliness, not primarily by polarity, which is why DC+ isn’t the preferred choice.

In GTAW, polarity changes where most of the arc heat goes. With the electrode positive, the arc concentrates heat into the tungsten electrode itself. The tungsten is non‑consumable and isn’t meant to absorb heavy heat, so using this polarity causes the electrode to overheat and wear quickly, and can even lead to tungsten contamination in the weld. Keeping the tungsten cool and the arc stable is essential in GTAW, so DC+ is not commonly used. Shielding gas flow, porosity, and arc stability are influenced by other factors like gas delivery and cleanliness, not primarily by polarity, which is why DC+ isn’t the preferred choice.