What is the main purpose of shielding gas in MIG welding?

The primary purpose of shielding gas in MIG welding is to prevent oxidation of the weld pool. When the molten metal is exposed to atmospheric air, it can react with oxygen and moisture, leading to defects in the weld, such as porosity and weak structural integrity. Shielding gas creates a protective environment around the weld zone, effectively displacing air and providing a barrier that maintains the purity and quality of the molten weld pool. This is crucial for ensuring that the weld finishes strong and free from contamination, which can otherwise compromise its strength and resistance to corrosion.

While options like creating a stronger weld or stabilizing the arc may touch on some aspects of the overall welding process, they do not directly address the fundamental protective role that shielding gas plays in safeguarding the weld from oxidation and atmospheric interference. Cooling the welding area is also not a primary function of the shielding gas; the heat management during welding is mainly handled by the welding parameters and the thermal characteristics of the materials rather than by the gas itself.