Which materials are commonly welded with AC in GTAW?

Which materials are commonly welded with AC in GTAW?

• A. Aluminum and Magnesium alloys
• B. Carbon steel
• C. Copper alloys
• D. Titanium alloys

Answer: (A)

AC in GTAW is used to manage oxide layers on metals that form stubborn surface films. Aluminum and magnesium alloys develop a thick, insulating oxide quickly, which blocks current flow and prevents proper fusion if not addressed. By applying alternating polarity, the arc cleans the surface during the negative half-cycle and then maintains a stable weld with the positive half-cycle, effectively removing oxide and allowing good wetting and fusion of the filler metal. This cleaning action is why these alloys are commonly welded with AC in GTAW. Other materials can be welded with GTAW using different polarities depending on the desired penetration and heat control, but they are not as dependent on the oxide-cleaning capability of AC. Carbon steel, titanium, and copper alloys are often welded with DC in many GTAW applications, though AC can be used for specific cases where cleaning of oxide films is advantageous.

AC in GTAW is used to manage oxide layers on metals that form stubborn surface films. Aluminum and magnesium alloys develop a thick, insulating oxide quickly, which blocks current flow and prevents proper fusion if not addressed. By applying alternating polarity, the arc cleans the surface during the negative half-cycle and then maintains a stable weld with the positive half-cycle, effectively removing oxide and allowing good wetting and fusion of the filler metal. This cleaning action is why these alloys are commonly welded with AC in GTAW.

Other materials can be welded with GTAW using different polarities depending on the desired penetration and heat control, but they are not as dependent on the oxide-cleaning capability of AC. Carbon steel, titanium, and copper alloys are often welded with DC in many GTAW applications, though AC can be used for specific cases where cleaning of oxide films is advantageous.