CWEA Mechanical Technologist II Practice Test

In MIG welding, carbon dioxide is the primary gas used for welding steels. This gas is chosen because it effectively produces a stable arc and good penetration when welding ferrous metals. When CO2 is used, it creates a deoxidizing environment that helps in reducing oxidation during the welding process, which is crucial for achieving a strong weld.

Additionally, CO2 is cost-effective and contributes to a more fluid weld puddle, which helps in the overall quality of the weld. While other gases like argon can be used in MIG processes, particularly when welding non-ferrous materials or in mixtures for specific applications, carbon dioxide remains the favored choice for steel due to its favorable properties and effectiveness in providing strong, durable welds.

Using gases such as helium, argon, or neon would not provide the same benefits for welding steels, making carbon dioxide the go-to option for this material in MIG welding applications.