Which of the following is a common FCAW shielding gas option?

• A. Argon only
• B. Carbon dioxide (CO2) or argon/CO2 blends
• C. Helium only
• D. Oxygen/argon blends

Answer: (B)

In gas-shielded flux-cored arc welding, the shielding gas is chosen to balance arc stability, penetration, and cost. The most common options are carbon dioxide alone or blends of argon with CO2. CO2 provides strong arc energy and good penetration at a relatively low cost, while adding argon helps stabilize the arc and improves bead appearance without losing too much penetration. Argon alone isn’t typical for FCAW on carbon steels, and helium-only shielding is costly with different arc characteristics. Oxygen/argon blends aren’t used because oxygen can cause oxidation and porosity in the weld. Therefore, carbon dioxide or argon/CO2 blends are the standard shielding gas options.