What is the primary function of shielding gas in GMAW?

The primary function of shielding gas in Gas Metal Arc Welding (GMAW) is to protect the molten weld pool from contamination. When welding, the heat generated can lead to the formation of a molten metal pool, which is vulnerable to atmospheric contaminants such as oxygen and nitrogen. These contaminants can result in defects like porosity and poor mechanical properties in the weld.

The shielding gas, which can be argon, carbon dioxide, or a mixture of both, creates a protective atmosphere around the weld zone. This barrier prevents these atmospheric gases from coming into contact with the molten weld metal, thereby ensuring a clean and sound weld. Proper shielding is vital for maintaining the quality of the weld and ensuring the integrity and strength of the finished joint.