Which gas is used to protect welds from atmospheric contamination?

Shielding gas plays a critical role in the welding process by creating a protective atmosphere around the weld pool. This gas prevents atmospheric contamination from detrimental elements such as oxygen, nitrogen, and moisture, which can lead to defects in the weld such as porosity, oxidation, and cracking.

In various welding processes, specifically in Gas Metal Arc Welding (GMAW) and Gas Tungsten Arc Welding (GTAW), the use of shielding gas is essential for achieving a high-quality weld. The choice of shielding gas can vary depending on the material being welded and the specific requirements of the welding procedure. Common types of shielding gases include argon, helium, and mixtures of argon with CO2.

While other gases like carbon dioxide and acetylene serve specific purposes in welding, they do not function as shielding gases in the same way. Carbon dioxide can be used in some welding applications, but it does not provide the comprehensive protective qualities required for shielding, and acetylene is primarily used for oxy-fuel welding rather than protecting welds from contamination. Thus, shielding gas is the correct terminology and concept associated with protecting welds during the welding process.