With which material is cleanliness considered a critical factor in GTAW?

Cleanliness is particularly critical when welding aluminum using Gas Tungsten Arc Welding (GTAW) due to the material's reactive nature. Aluminum undergoes rapid oxidation when exposed to air, forming a thin layer of aluminum oxide on its surface. This oxide layer has a significantly higher melting point than the aluminum itself and can interfere with proper fusion if not removed.

For successful welding, the aluminum surface must be free of contaminants such as dirt, grease, oils, and the oxide layer. Proper cleaning techniques involve methods such as chemical cleaning or mechanical scrubbing with a stainless steel brush dedicated to aluminum to ensure that the surface is adequately prepared for welding.

In contrast, while cleanliness is also important for stainless steel, mild steel, and copper, the specific challenges that aluminum presents make cleanliness even more crucial in that context. Each of these other materials has its own welding considerations, but the rapid oxidation of aluminum and the impact it has on weld quality elevate the importance of cleanliness in its preparation for GTAW.