Flux-Cored Welding Guide — FCAW Settings & Technique

Complete flux-cored welding guide: self-shielded vs gas-shielded (dual-shield) FCAW, wire selection by application, voltage and wire speed settings, and all-position technique for structural and heavy fabrication.

Flux-cored arc welding (FCAW) uses a tubular wire electrode filled with flux compounds. It combines the high deposition rates of MIG with the shielding flexibility of stick welding, making it the dominant process for structural steel fabrication, heavy plate, shipbuilding, and outdoor construction welding.

Two Distinct Processes

FCAW splits into two categories that behave differently in practice:

Self-shielded (FCAW-S) runs without external gas. The flux core generates all the shielding. This makes it the go-to process for outdoor structural work, bridge construction, and field welding where wind would blow away MIG shielding gas. Common wires include E71T-11 (all-position) and E71T-8 (low hydrogen, all-position). Polarity is typically DCEN.

Gas-shielded (FCAW-G / dual-shield) adds external shielding gas, usually 75/25 argon/CO2 or 100% CO2. The dual shielding produces cleaner welds with less spatter and better mechanical properties. Standard for shop fabrication and heavy structural work. Common wires include E71T-1 (all-position) and E70T-1 (flat and horizontal). Polarity is DCEP.

Where Flux-Core Excels

Flux-cored welding puts down more metal per hour than any other semi-automatic process. Deposition rates of 12-25 lbs/hour are common with dual-shield on heavy plate, compared to 3-8 lbs/hour for solid MIG wire. That speed advantage makes FCAW the default choice for multi-pass welds on steel 3/8" and thicker.

The process also handles dirty, rusty, and mill-scaled steel better than MIG. The flux compounds contain deoxidizers and scavengers that tolerate surface contamination that would cause porosity with solid wire.

Settings Overview

FCAW runs at higher wire feed speeds and voltages than solid MIG wire for the same material thickness. Self-shielded wire typically runs at DCEN polarity, gas-shielded at DCEP. Stick-out (contact-tip-to-work distance) is longer than MIG, typically 3/4" to 1-1/4" depending on wire type. Getting stick-out right is critical since it directly affects amperage and penetration.

Articles in This Section

The guides below cover wire selection, settings charts, technique for vertical-up and overhead, slag management, and troubleshooting common FCAW problems like worm tracking and porosity.

All Articles