What type of shielding gas is used to protect steel welds?

The correct choice for the type of shielding gas used to protect steel welds is carbon dioxide. When welding steel, particularly with processes like MIG (Metal Inert Gas) or GMAW (Gas Metal Arc Welding), carbon dioxide serves as an effective shielding gas due to its ability to form a protective atmosphere around the weld pool. This helps to prevent contamination from factors such as oxygen and moisture, which can lead to issues like porosity and other weld defects.

In addition to being economical, carbon dioxide enhances the arc stability and provides good penetration during the welding process. It's important for welders to understand the properties of different shielding gases and their appropriate applications. While other gases, such as argon and helium, are utilized for welding non-ferrous metals or specific applications, carbon dioxide is predominantly recognized for its efficacy in protecting steel welds, making it the preferred choice in conventional mild steel welding.