Welding Level 3 GTAW Line F 2025 – 400 Free Practice Questions to Pass the Exam

Using alternating current (AC) for welding aluminum provides a significant advantage in terms of better cleaning action due to the unique characteristics of the AC waveform. In AC welding, the current alternates between positive and negative polarities, which helps to effectively clean the oxide layer that forms on the surface of aluminum.

Aluminum naturally develops a thin layer of aluminum oxide when exposed to air, which can affect the quality of the weld. The positive half of the AC cycle causes the electrode to act as anodes, which helps to break down and remove this oxide layer and expose the pure aluminum underneath. This cleaning action improves arc stability and creates a better bonding surface for successful welding.

The other options do not capture the specific advantages offered by AC for aluminum welding. While factors like heat input, travel speeds, and electrode wear are considerations in welding, they do not directly relate to the effectiveness of AC in cleaning aluminum surfaces. Therefore, the emphasis on cleaning action is what positions it as the main advantage of AC in the context of aluminum welding.