In gas metal arc welding, what is the purpose of the shielding gas?

In gas metal arc welding (GMAW), the primary role of the shielding gas is to protect the weld puddle from atmospheric contamination. When the welding arc is generated, it produces a molten pool of metal that is susceptible to oxidation and other harmful reactions with elements present in the air, such as nitrogen and oxygen. The shielding gas creates a protective atmosphere around the weld, preventing those contaminants from compromising the quality of the weld by forming defects like porosity or inclusions.

The effectiveness of this shielding is crucial, as a clean weld is required for optimal strength and durability. Common shielding gases used in GMAW include argon, carbon dioxide, or a mix of both, which help to stabilize the arc and promote good wetting of the base metal. This focus on protection ensures that the integrity of the weld is maintained throughout the welding process.