Which gas is primarily used in GTAW welding for its inert properties?

In Gas Tungsten Arc Welding (GTAW), Argon is primarily used as the shielding gas due to its inert properties. This means that Argon does not react with molten metal or with the electric arc created during the welding process. The use of Argon helps to protect the weld area from atmospheric contamination, which is crucial for achieving high-quality welds, particularly with nonferrous metals like aluminum and magnesium, as well as stainless steel.

Argon is favored because it is not only inert but also denser than air, providing an effective shield that minimizes oxidation and other undesirable reactions. While helium can also be used in GTAW, particularly for its ability to produce a hotter arc and deeper penetration, Argon is more widely used due to its availability and cost-effectiveness.

The other gases listed, such as oxygen and nitrogen, are reactive and would alter the properties of the weld by promoting oxidation or nitriding, which can lead to defects in the welded joint. Therefore, their use as shielding gases in GTAW is not suitable, which reinforces the choice of Argon as the primary inert gas for this application.