What is the function of flux in FCAW and SMAW?

• A. Flux creates shielding for the weld plume; in FCAW it can generate shielding gas or slag that protects the weld, and in SMAW it provides slag and shielding during welding.
• B. Flux is only used to clean the surface.
• C. Flux melts to add extra metal.
• D. Flux increases current.

Answer: (A)

Flux provides shielding for the weld and helps protect the molten metal as it cools. In SMAW, the flux coating on the electrode melts and forms a protective slag on the weld; it also releases gases that shield the weld pool from the surrounding air. In FCAW, the flux inside the welding wire can do one of two things: in gas-shielded FCAW it generates shielding gas, enveloping the weld, and in self-shielded FCAW it forms slag that blankets the weld as it solidifies. This shielding prevents oxidation and contamination and aids deoxidation, leading to a sound weld. Flux isn’t mainly used to clean the surface, to add significant extra metal, or to change the welding current.