What shielding gas is used for FCAW?

• A. CO2 used as auxiliary shielding gas, also can use 75% argon/25% CO2
• B. Pure Argon
• C. Helium
• D. No shielding gas used

Answer: (A)

Shielding gas protects the molten weld from air when using flux-cored wire. In FCAW, you can weld with a gas shield (FCAW-G) or without external gas (FCAW-S). For the gas-shielded method, CO2 is a common, economical choice and provides solid penetration on carbon steels. An argon–CO2 blend, such as around 75% argon with 25% CO2, is also widely used because it can improve arc stability and bead appearance. Pure argon is less typical for FCAW of carbon steels due to cost and because it changes heat and penetration characteristics. Helium is not a common shielding gas for FCAW in typical structural steels. The self-shielded variant, by contrast, does not use any shielding gas at all, which is why choosing “no shielding gas” wouldn’t apply to the gas-shielded FCAW option.