Argon is the most used welding gas, particularly for gas tungsten arc welding (GTAW) and gas metal arc welding (GMAW). It is used for welding non-ferrous metals, such as aluminum, magnesium, and titanium, and provides good arc stability and penetration.
Carbon dioxide is often used in combination with other gases, such as argon or helium, for welding steel and other ferrous metals. It provides good penetration and is particularly useful for welding thicker materials.
Helium is commonly used in GTAW and is often used in combination with argon for welding aluminum and other non-ferrous metals. It provides a higher heat input than argon and is particularly useful for welding thicker materials.
Oxygen can be used as a welding gas for cutting, brazing, and welding applications. It can provide better penetration than other gases, but also increases the risk of oxidization and porosity in the weld.
Nitrogen is sometimes used as a welding gas for welding stainless steel and other non-ferrous metals. It provides good penetration and can help prevent oxidation but can also increase the risk of porosity in the weld.