Which gas is commonly used as a shielding gas in GMAW?

Argon is widely used as a shielding gas in Gas Metal Arc Welding (GMAW) due to its inert properties. This noble gas does not react with the molten weld pool, which helps to protect the weld from contamination by atmospheric elements such as oxygen and nitrogen. The use of argon ensures a stable arc and promotes a quality weld with good penetration and minimal spatter.

In GMAW processes, using an inert shielding gas like argon creates an ideal welding environment, particularly for aluminum and other non-ferrous metals. Its effectiveness is amplified when mixed with small percentages of other gases, such as carbon dioxide, to enhance the arc stability and improve overall weld characteristics.

In contrast, the other gases listed do not possess the same qualities for shielding. Oxygen, while useful in certain welding processes, can cause oxidation and compromise weld integrity. Hydrogen can lead to embrittlement in certain metals, and nitrogen, while it may appear inert under certain conditions, can also introduce undesirable effects. Therefore, argon remains the preferred choice for effective shielding in GMAW applications.