What must be done to the oxide layer when welding aluminum in GTAW?

When welding aluminum in Gas Tungsten Arc Welding (GTAW), it is crucial to address the oxide layer that forms on the surface of the metal. This oxide layer is primarily aluminum oxide, which has a much higher melting point than aluminum itself. If this layer is not removed prior to welding, it can impede the fusion of the metal and lead to poor weld quality, lack of penetration, or porosity in the weld.

Using a stainless steel wire brush is a common and effective method to effectively clean the oxide layer from the aluminum surface before welding. The stainless steel bristles are abrasive enough to remove the oxide, while also minimizing the risk of contamination since steel can introduce iron into aluminum, which can affect weld quality. Ensuring that the aluminum is clean and free from the oxide layer helps in achieving a strong, high-quality weld.

In contrast, other methods or choices do not adequately address the removal of this critical layer. For instance, using an acetylene torch could risk heating the aluminum improperly or causing distortion. Leaving the oxide layer as is will hinder the ability of the weld to penetrate and bond effectively. Finally, welding without any preparation would likely result in unsatisfactory welds due to the interference caused by the oxide layer.

Thus,