What are the most commonly used shielding gases in gas metal arc welding?

The most commonly used shielding gases in gas metal arc welding (GMAW), also known as MIG welding, are indeed carbon dioxide (CO2) and a mixture of argon and CO2. This combination is favored for its effectiveness in stabilizing the arc and producing high-quality welds.

Argon serves as an inert gas that ensures a clean welding environment by preventing oxidation and contamination of the weld pool. When mixed with CO2, it improves arc stability and control, particularly on varying materials and thicknesses. The addition of CO2 also results in deeper penetration and a flatter bead profile, making it a versatile choice for various applications, especially in structural welds and manufacturing.

The use of pure carbon dioxide can be advantageous for its cost-effectiveness and the favorable characteristics it brings to penetrate and fuse metals, particularly for materials like mild steel. This combination of gases provides a good balance between performance and cost, making it a standard in the industry.

In contrast, other options such as helium and oxygen, argon with nitrogen, and hydrogen with acetylene do not provide the same effectiveness and quality in MIG welding applications. For instance, helium is typically used for specific applications involving non-ferrous metals but is not a common choice in standard GMAW