How does AC benefit the arc stability when welding aluminum?

Choosing the option that states AC helps to break up the oxide layer is accurate and reflects a key advantage of using alternating current (AC) when welding aluminum. Aluminum naturally forms a thin, tough oxide layer when exposed to air, which can hinder proper fusion between the base metal and the filler material. When the welder uses AC, the polarity alternates between positive and negative, which facilitates the removal of this oxide layer during the positive half-cycle of the AC waveform. This cleaning action is crucial as it exposes the fresh aluminum substrate beneath the oxide, allowing for better penetration and bonding of the weld.

The other options, while they address different aspects of welding, do not directly contribute to arc stability in the context of aluminum welding with AC. For example, increased arc length does not inherently improve stability and may actually lead to a less stable arc. Improved heat distribution is beneficial for thermal management, but it is not specifically enhanced by the use of AC. Lastly, while reducing energy consumption is a valid concern in various welding processes, it does not specifically pertain to the stability of the arc in aluminum welding with AC currents. Therefore, the breaking up of the oxide layer is a critical element that underscores the effectiveness of AC in maintaining a stable arc during aluminum welding