Which gas is commonly used as a shielding gas in MIG welding?

Argon is commonly used as a shielding gas in MIG (Metal Inert Gas) welding because it is an inert gas that does not react with the molten metal during the welding process. Its inert properties help to protect the weld pool from atmospheric contamination, such as oxygen and moisture, which can lead to defects in the weld, including porosity and oxidation. Argon provides a stable arc and good penetration, making it ideal for welding a variety of materials, particularly aluminum and other non-ferrous metals.

In addition, argon can be mixed with other gases, such as carbon dioxide, to enhance the welding process further. This flexibility in shielding gas composition allows for improved control over the welding characteristics, such as the heat input and bead appearance.

To summarize, argon is favored in MIG welding for its ability to create a protective environment during the welding operation, ensuring high-quality welds and minimizing defects.