04 Processes, positions, procedures · 16 min
The five processes on the paper
SMAW, GMAW, FCAW, GTAW, SAW — how they run, what they leave behind, what you look for.
| Process | Also called | Shielding | Inspector notes |
|---|---|---|---|
| SMAW | Stick / shielded metal arc | Flux on the electrode; slag + gas | Slag inclusions, undercut, starts/stops, low-H storage |
| GMAW | MIG / MAG, solid wire | External gas (Ar, CO₂, mixes) | Lack of fusion on short-circuit, spatter, porosity from draft |
| FCAW | Flux-cored | Flux in the tubular wire ± gas | T-1 gas-shielded vs T-11 self-shielded; slag; smoke |
| GTAW | TIG | Inert gas, usually Ar | Tungsten inclusions, oxidation from lost purge, autogenous roots |
| SAW | Submerged arc | Blanket of granular flux | Used on thick plate, often automatic; flux recovery, bead shape |
Polarity, in one paragraph
DCEP (electrode positive, reverse polarity) puts more heat in the workpiece for SMAW and is the usual home of E4918 / E7018. DCEN (electrode negative, straight polarity) puts more heat in the electrode — common for some GTAW and certain electrodes. AC swaps sixty times a second; some E4313 / E6013 and certain 7018-A1 / AC-rated 7018 run on it. GMAW spray transfer wants DCEP and enough voltage and argon-rich gas.
GMAW transfer modes
- Short-circuit (short-arc): wire touches the puddle. Low heat, thin material, out-of-position. Fusion at the toes is the inspection worry.
- Globular: large drops, messy, usually a transition you do not want to live in.
- Spray: fine droplets, high heat, flat and horizontal, argon-rich mix. Excellent fusion when the procedure is right.
- Pulsed spray: spray in a pulse, lower average heat, more positions.