What is the purpose of using inert gas in MIG welding?

The purpose of using an inert gas in MIG welding is primarily to protect the weld from atmospheric contamination. Inert gases, such as argon or helium, form a shielding atmosphere around the weld pool. This shielding prevents oxygen, nitrogen, moisture, and other contaminants in the air from affecting the molten metal.

Contaminants can lead to issues like porosity—tiny holes in the weld caused by trapped gases—or even weld defects that weaken the joint. By filling the environment around the weld pool with inert gas, the risk of oxidation and other detrimental reactions is minimized, contributing to a stronger, more reliable weld.

While increasing the temperature of the weld, providing additional material for welding, or making the welding process faster may have other connections in welding practices, they do not accurately describe the primary function of inert gases in MIG welding. The shielding gas's main role is to ensure a clean, uncontaminated welding environment for high-quality results.