What is the main advantage of using alternating current for welding aluminum?

Using alternating current for welding aluminum primarily offers the advantage of cleaning the surface of the metal. Aluminum develops a natural oxide layer that can inhibit the proper formation of a weld. The alternating current (AC) in GTAW involves both a positive and negative cycle, which efficiently removes the oxide film during the positive phase. This cleaning action is crucial because it ensures good fusion between the base metal and the filler material, leading to a stronger and more reliable weld.

The alternating nature of AC helps in breaking the oxide barrier, allowing for better penetration and overall weld quality. This is particularly important in aluminum welding, where the removal of the oxide layer significantly improves adhesion and structural integrity of the joint. Therefore, the cleaning effect of AC is vital for achieving successful welds in aluminum applications.