What is the function of shielding gas in welding?

The function of shielding gas in welding is primarily to protect the weld pool from contamination and oxidation. When welding occurs, the high temperatures cause the base metals and filler materials to melt, creating a molten weld pool. This weld pool is vulnerable to oxidation and contamination from the surrounding atmosphere, which can lead to defects in the weld, such as porosity or lack of fusion.

Shielding gases, typically inert gases such as argon or helium, or active gases like carbon dioxide, surround the weld area and create a protective barrier. This barrier prevents atmospheric gases, particularly oxygen and nitrogen, from interacting with the hot metal. By maintaining a clean environment around the weld pool, shielding gas ensures a higher quality weld with improved structural integrity and appearance.

In contrast, while factors such as speed of the welding process and cooling of the weld pool are important considerations in welding, they are not the primary roles of shielding gas. Providing an electric charge is also not a function of shielding gas, as the welding arc is created by the electrical current passing through the electrode and workpieces, independent of the shielding gas.