In GTAW on non-ferrous metal, which polarity is used?

In GTAW on non-ferrous metal, which polarity is used?

• A. Alternating current
• B. Direct current electrode negative
• C. Direct current electrode positive
• D. Direct current with balanced polarity

Answer: (A)

Alternating current is used in GTAW on non-ferrous metals because these materials often have oxide surfaces and require both oxide removal and controlled heat delivery. The arc with alternating polarity provides a cleaning action that helps break up and remove the oxide film, while the opposite polarity portion concentrates heat in the weld zone to promote proper fusion and penetration. This balance is essential for metals like aluminum and other non-ferrous alloys, where a stable arc and clean surface lead to a solid weld joint. Direct current with a single polarity tends to heat mainly in one area and doesn’t provide the same oxide-cleaning effect, while a purely balanced DC setup isn’t the standard practice for these materials.

Alternating current is used in GTAW on non-ferrous metals because these materials often have oxide surfaces and require both oxide removal and controlled heat delivery. The arc with alternating polarity provides a cleaning action that helps break up and remove the oxide film, while the opposite polarity portion concentrates heat in the weld zone to promote proper fusion and penetration. This balance is essential for metals like aluminum and other non-ferrous alloys, where a stable arc and clean surface lead to a solid weld joint. Direct current with a single polarity tends to heat mainly in one area and doesn’t provide the same oxide-cleaning effect, while a purely balanced DC setup isn’t the standard practice for these materials.