Which of these shielding gases are commonly used in GMAW?

In Gas Metal Arc Welding (GMAW), the commonly used shielding gases are argon and helium. These gases serve a vital role in protecting the weld pool from atmospheric contamination, which can lead to defects in the weld.

Argon is the primary gas utilized in GMAW due to its inert nature, which means it does not react with the molten metal or other elements in the welding process. This helps to achieve a smooth and stable arc, as well as good penetration and bead appearance. Helium, while also inert, contributes to increased heat and a fluid weld pool, which can be beneficial for certain materials and joint configurations. The combination of argon and helium can enhance the welding process, particularly when working with non-ferrous metals or when higher heat input is required.

The other combinations of gases do not provide the ideal properties for GMAW. For instance, argon and oxygen would introduce oxygen into the weld area, which can lead to oxidation and poor weld quality. Similarly, using helium with carbon dioxide can lead to an unstable arc and increased spatter, while carbon dioxide and nitrogen would not effectively protect the weld area and can lead to unwanted reactions that compromise weld integrity. Therefore, argon and helium are the most suitable shielding gases