What gas is commonly used for purging stainless steel during GTAW?

Argon is commonly used for purging stainless steel during Gas Tungsten Arc Welding (GTAW) because it is an inert gas. Inert gases do not react with the molten metal, which helps to prevent contamination and oxidation. When stainless steel is welded, it is crucial to maintain a purified environment around the weld area to ensure that the weld maintains its integrity and does not become brittle or weakened by reactions with oxygen or moisture in the air.

Using argon for purging allows for effective shielding of the weld area from the atmosphere, thereby protecting it and ensuring that the final weld is strong and free of defects. Furthermore, argon is readily available and economical, making it a popular choice in many welding applications.

When considering other options, oxygen and carbon dioxide are reactive gases that can lead to oxidation and compromise the quality of the weld. Helium is also an inert gas and can be used for purging, but it is generally less common than argon due to its higher cost and different thermal properties.