Why is aluminum particularly sensitive to cleanliness in the GTAW process?

Aluminum is particularly sensitive to cleanliness in the GTAW process because it oxidizes rapidly when exposed to air. This oxidation forms a thin layer of aluminum oxide on the surface, which has a much higher melting point than the aluminum itself. If the oxide layer is not adequately removed prior to welding, it can hinder the arc stability and prevent proper fusion between the weld metal and the base material.

Since the performance of the weld is critically dependent on the quality of the joint, any contaminants or oxide present can lead to porosity, weak welds, or improper bead appearance. Therefore, ensuring that the aluminum surface is clean and free of oxide is essential for achieving high-quality welds in the GTAW process.