Fluxcore

Flux-core welding, often referred to as flux-cored arc welding (FCAW), is a semi-automatic or automatic welding process that uses a continuous tubular electrode filled with flux. The flux inside the core provides shielding against atmospheric contamination and can contribute alloying elements to the weld metal. The process is typically powered by a constant-voltage power source and a wire-feed system that advances the consumable electrode into the weld pool.

Most FCAW processes are categorized into two broad families. FCAW-G uses an external shielding gas, such as carbon dioxide or a CO2/argon mixture, supplied through the welding torch or a dedicated gas nozzle. FCAW-S, or self-shielded FCAW, relies on the flux to generate shielding gas and slag, allowing welding without an external gas supply.

FCAW offers high deposition rates and deep penetration, making it well suited for thick sections and field fabrication. It performs well outdoors and in windy conditions, and is widely used for carbon and low-alloy steels, structural work, shipbuilding, and pipeline fabrication. Some FCAW wires can tolerate moderate surface contamination and require less pre-cleaning than other methods.

Limitations include the slag that must be chipped away in many applications, relatively high heat input that can cause distortion, and potential spatter. The quality and characteristics of the weld are strongly dependent on the flux composition and the control of the shielding gas in FCAW-G. Welding aluminum or dissimilar metals is not typical with standard FCAW wires.

Typical equipment includes a welding power source, a wire-feed mechanism, and a continuous spool of tubular flux-core electrode. Operators should follow safety practices for welding fume exposure, UV radiation, and fire risk, and ensure adequate ventilation, especially when using FCAW-G in enclosed spaces or when welding dirty or rusty plate.