What is classified as an "inert gas" in the context of GTAW?

In the context of Gas Tungsten Arc Welding (GTAW), an "inert gas" refers to a type of shielding gas that does not react with the molten weld pool or the base metals being welded. Argon and helium are the two primary gases utilized in GTAW for this purpose.

Argon is denser than air and provides excellent shielding properties, making it ideal for protecting the weld area from contamination and atmospheric gases. Helium, on the other hand, can be used to enhance heat input, which may be beneficial for specific materials or thicker sections of metal. Both gases are chemically inert, meaning they do not participate in chemical reactions during the welding process, which helps ensure the integrity and quality of the weld.

In contrast, options like oxygen, carbon dioxide, and nitrogen can chemically react with the molten metal. For instance, oxygen can cause oxidation, while carbon dioxide can lead to the formation of carbides or other detrimental effects on the weld. Therefore, using argon or helium as inert gases is critical in maintaining the purity and performance of the weld joint in GTAW applications.