Which statement about GTAW using alternating current is not true?

Which statement about GTAW using alternating current is not true?

• A. High frequency is for arc starts only
• B. High frequency is for arc starts and arc stabilization
• C. AC welding Magnesium does not require shielding gas
• D. Alternating current cannot be used for welding some materials

Answer: (A)

In GTAW with alternating current, high frequency does more than just start the arc. It also helps keep the arc stable during the AC cycle by ionizing the area around the tungsten and workpiece, which reduces arc wander and improves control. That’s why saying high frequency is for arc starts only isn’t accurate—the stabilization effect is a real and important part of using AC TIG. For magnesium, shielding gas is essential to prevent rapid oxidation and to produce a clean weld surface, so the idea that shielding gas isn’t required is not correct. Shielding gas protects the weld zone throughout the process. AC welding is particularly useful for nonferrous metals like aluminum and magnesium, and while some materials weld more easily with direct current, AC can be used on others as well. So the notion that AC cannot be used for welding some materials isn’t accurate in general.

In GTAW with alternating current, high frequency does more than just start the arc. It also helps keep the arc stable during the AC cycle by ionizing the area around the tungsten and workpiece, which reduces arc wander and improves control. That’s why saying high frequency is for arc starts only isn’t accurate—the stabilization effect is a real and important part of using AC TIG.

For magnesium, shielding gas is essential to prevent rapid oxidation and to produce a clean weld surface, so the idea that shielding gas isn’t required is not correct. Shielding gas protects the weld zone throughout the process.

AC welding is particularly useful for nonferrous metals like aluminum and magnesium, and while some materials weld more easily with direct current, AC can be used on others as well. So the notion that AC cannot be used for welding some materials isn’t accurate in general.