Steel fabrication shops and job sites around the world tend to rely on four “workhorse” arc-welding processes:
- GMAW (Gas Metal Arc Welding) — commonly called MIG/MAG
- SMAW (Shielded Metal Arc Welding) — commonly called Stick
- FCAW (Flux-Cored Arc Welding) — self-shielded or gas-shielded (“Dual Shield”)
- SAW (Submerged Arc Welding) — high-deposition, mechanized/automatic production welding
Quick Comparison: Which Process Fits Your Job?
| Process | Shielding method | Best for | Where it shines | Common limitations |
|---|---|---|---|---|
| GMAW (MIG/MAG) | External shielding gas + solid wire | General fabrication, sheet to medium plate | Fast, clean, easy to automate, low slag cleanup | Wind-sensitive outdoors, gas supply needed |
| SMAW (Stick) | Flux-coated electrode creates shielding + slag | Field welding, repairs, construction | Portable, tolerant of rust/scale, works in wind | Slower, more skill-dependent, electrode changes, more cleanup |
| FCAW (Flux-cored) | Flux core (may also use gas) | Structural steel, heavy fillets, high deposition | Very productive, good penetration, outdoor option (self-shielded) | More fumes/spatter than GMAW, slag removal |
| SAW (Submerged) | Flux blanket covers arc/weld pool | Long seams, thick plate, vessels, pipes | Extremely high deposition, consistent quality, easy mechanization | Mostly flat/horizontal, equipment/fixtures required |
Standard Process Names (ISO 4063) — Helpful for Drawings & WPS Documents
If you work globally, you’ll often see ISO process numbers on drawings, work instructions, and WPS packages. Examples include: 111 (manual metal arc / SMAW), 131 (MIG), 135 (MAG), 136 (tubular cored with active gas shield), 114 (self-shielded tubular cored), 121 (submerged arc with one wire).
1) GMAW (MIG/MAG): Gas Metal Arc Welding
What it is
GMAW uses a continuously fed wire electrode and an externally supplied shielding gas to protect the molten weld pool from the atmosphere. It’s one of the most common production processes because it’s fast and versatile.
Typical steel applications
General fabrication: frames, brackets, light-to-medium structural components
Manufacturing lines where speed + repeatability matter
Thin materials where you want controlled heat input and minimal cleanup (depending on transfer mode)
Why fabricators choose it
High travel speed and relatively clean welds (little slag)
Easy to learn compared with some manual processes (though quality still depends on fit-up and settings)
Excellent for semi-automatic and robotic welding cells
Watch-outs (common real-world issues)
Wind and drafts can disrupt shielding gas, causing porosity—so outdoor use needs wind blocks or process changes.
Surface contamination (oil, paint, heavy rust) can quickly degrade quality.
2) SMAW (Stick): Shielded Metal Arc Welding
What it is
SMAW uses a flux-coated, fixed-length consumable electrode. The flux breaks down in the arc to provide shielding and forms slag that protects the weld as it cools. It remains a core “field” process and a foundational skill for welders.
Typical steel applications
Construction and field erection (stair/handrail installation, joists, site welding)
Maintenance, repair, and “dirty” conditions where perfect prep isn’t realistic
Remote jobs where shielding gas logistics are difficult
Why fabricators choose it
Portability (simple equipment, no gas bottles required)
Works well outdoors and in less controlled environments
Huge electrode variety for different steels and positions
Watch-outs
Lower productivity (electrode changes, slower deposition)
More operator skill needed to keep arc length, travel angle, and heat input consistent
Slag removal between passes is required for multi-pass welds
3) FCAW: Flux-Cored Arc Welding (Self-Shielded vs Gas-Shielded)
What it is
FCAW is similar to GMAW in equipment style (wire feeder, gun), but the electrode is a tubular wire filled with flux. Some variants use external shielding gas (often called “dual shield”), while others are self-shielded and rely on the flux system alone.
Two common variants (and when they win)
FCAW-G (Gas-shielded / “Dual Shield”)
Great for shop fabrication where you want high deposition and strong welds
Often chosen for structural steel fillets and multi-pass work
FCAW-S (Self-shielded)
A strong option for outdoor structural welding because it does not rely on external shielding gas
Particularly useful when wind would disrupt GMAW gas coverage
Typical steel applications
Structural fabrication, bridge components, heavy frames
Multi-pass fillet welds where productivity matters
Job-site structural welding (especially FCAW-S)
Watch-outs
Slag removal is still part of the workflow
Typically more fume and spatter than clean GMAW setups (plan ventilation and cleanup)
4) SAW: Submerged Arc Welding (High-Deposition Production)
What it is
SAW forms an arc under a blanket of powdered/granular flux, which generates protection and slag. Shielding gas is not normally required, and the arc is typically not visible because it’s submerged under flux.
Where SAW dominates
SAW is widely used for thick steel sections and long, straight seams, including shipbuilding, structural steel fabrication, pressure vessels, and pipe/pipeline-type production—especially where mechanization improves repeatability and throughput.
Why fabricators choose it
Very high deposition rate and high productivity
Excellent consistency for validated procedures
Highly compatible with mechanized/automatic systems
Watch-outs
Usually limited to flat/horizontal welding positions because the flux blanket must stay in place
Requires more equipment, fixtures, flux handling/recovery—best for repetitive production, not small one-off jobs
How to Choose
If you’re welding outdoors (windy site conditions)
Start with SMAW or FCAW-S
Use GMAW only if you can reliably control drafts with screens/tents
If you’re in a fabrication shop optimizing throughput
GMAW for clean, fast general welding and automation cells
FCAW-G for heavy structural fillets and high-deposition multi-pass welds
SAW for long seams on thick plate where mechanization pays back quickly
If your welds are long, straight, and repetitive on thick plate
- SAW is often the first process to evaluate
Quality & Safety Notes You Shouldn’t Skip
Ventilation and fume control matter for every arc process—position airflow to move fumes away from the breathing zone and use appropriate controls (local exhaust, extraction, work practices).
Regardless of process, high-performing shops standardize: joint prep, fit-up control, WPS parameters, interpass cleaning, and inspection routines.
Codes & Documentation: WPS/PQR Still Drive Real-World Acceptance
If you ship steel into global projects, customers may require welding to recognized codes and documented procedures. For example:
AWS D1.1 is a major structural steel welding code used in many steel construction projects, covering areas like fabrication, inspection, and qualification.
ASME BPVC Section IX is widely referenced for qualification rules for welding/brazing/fusing procedures and personnel when required by other ASME code sections.
WPS/PQR concepts are central to procedure control and qualification workflows.
FAQ
Is MIG the same as GMAW?
“MIG” is commonly used as a shop term, but the formal process name is GMAW (Gas Metal Arc Welding).
Which is best for structural steel: GMAW or FCAW?
Both can be used successfully. Many fabricators choose FCAW (especially FCAW-G) for high-deposition fillets and multi-pass structural work, while GMAW is popular for clean, fast general welding and automation—your joint type, position, and production goals usually decide.
Why is stick welding still so common?
Because SMAW is portable and field-friendly, tolerates harsher conditions, and doesn’t rely on shielding gas logistics—making it reliable for site erection and repairs.
When does SAW make the most sense?
When you have long seams, thick steel, repetitive production, and the ability to use mechanized/automatic setups—common in vessels, pipe production, shipbuilding, and heavy fabrication.
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