TIG/GTAW Welding Process (141) — Complete Guide
Introduction
TIG (Tungsten Inert Gas) or GTAW (Gas Tungsten Arc Welding), process number 141 (ISO 4063), uses an arc between a non-consumable tungsten electrode and the workpiece, shielded by inert gas (argon or helium). It produces the highest quality welds of any arc welding process.
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Equipment
- Power source — Inverter, DC and/or AC, with HF or Lift-Arc
- TIG torch — Air-cooled (up to ~200A) or water-cooled (>200A)
- Gas bottle — Argon (most common), helium or mixtures
- Flowmeter — Typically 6-15 l/min
- Foot pedal or remote — Current control during welding
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Tungsten Electrodes
| Colour | Composition | Application |
|---|---|---|
| Green | Pure tungsten (WP) | AC — aluminium |
| Red | 2% Thorium (WT20) | DC — steels (being phased out) |
| Gold | 1.5% Lanthanum (WL15) | DC and AC — universal replacement |
| Blue | 2% Lanthanum (WL20) | DC and AC — excellent striking |
| Grey | 2% Cerium (WC20) | DC — low currents |
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Shielding Gases
| Gas | Application |
|---|---|
| Argon | Universal — steel, stainless, aluminium, copper, titanium |
| Helium | Copper, thick aluminium — higher heat input |
| Ar + He | Thick aluminium |
| Ar + H₂ (2-5%) | Austenitic stainless (NEVER on carbon steel!) |
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Current Selection
| Type | Application |
|---|---|
| DC− (DCEN) | Steel, stainless, copper, titanium — 70% heat on workpiece |
| AC | Aluminium and magnesium — cathodic cleaning removes oxides |
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Typical Parameters (Stainless Steel, DC−, Argon)
| Thickness (mm) | Tungsten Ø (mm) | Current (A) | Filler Ø (mm) |
|---|---|---|---|
| 1.0 | 1.6 | 40-60 | 1.6 |
| 2.0 | 2.4 | 80-120 | 2.4 |
| 3.0 | 2.4 | 100-150 | 2.4 |
| 5.0 | 3.2 | 150-200 | 3.2 |
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Advantages and Disadvantages
Advantages: Highest quality, precise heat control, no slag or spatter, all positions, all metals.
Disadvantages: Low deposition rate, high equipment cost, requires high skill, sensitive to draughts.
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Reference Manufacturers
For TIG welding, reference manufacturers include Fronius (MagicWave, TransTIG series), Lincoln Electric (Aspect, Precision TIG series), ESAB (Rebel, Caddy TIG series), Kemppi (MasterTig series) and Miller (Dynasty, Syncrowave series). For TIG rods and consumables, voestalpine Böhler Welding and ESAB are key suppliers.
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*Article based on AWS Welding Handbook materials and ISO 4063. Published on WeldFC Academy.*