Non-consumable tungsten electrode produces the arc; filler wire (if needed) is fed separately. Argon gas shields the electrode and molten pool from the nozzle.
Key advantages: stable arc (even at 5A), zero spatter, small heat affected zone, beautiful weld bead.
The tradeoff: TIG is slow — 1/3 to 1/5 the speed of CO₂ welding.
• Stainless steel sheet (0.5-3mm) — food equipment, medical devices
• Aluminum precision welding — bicycle frames, aircraft tubing
• Titanium — aerospace components
• Copper tube — refrigeration lines
• Root pass for thick plate multi-layer welding
DC (straight polarity) for steel. AC for aluminum — the reverse half-cycle uses argon ions to bombard and break up the Al₂O₃ oxide layer. This is why aluminum MUST use AC TIG.