What two gases are most commonly used for FCAW-GS welding?

• A. 100% CO2 and 75% AR/25% CO2
• B. 50% CO2/50% Argon
• C. 100% Argon and 0% CO2
• D. 25% CO2/75% Argon

Answer: (A)

Shielding gas choices for FCAW-GS welding revolve around using carbon dioxide and argon. CO2 provides good penetration and is cost-effective, while argon helps stabilize the arc and produces a smoother bead. In practice you’ll see two common gas options: pure CO2, and a CO2/argon mix (for example around 75% argon and 25% CO2) that balances penetration, bead shape, and spatter. Pure argon is not as typical for FCAW-GS because it doesn’t give the same penetration characteristics, so the standard approach highlights both CO2 and argon as the main shielding gases. That's why the option showing both a pure CO2 choice and a CO2/argon mixture is the best representation of what’s most commonly used.