TIG (Tungsten Inert Gas) welding, officially known as Gas Tungsten Arc Welding (GTAW), is a precision welding process that uses a non-consumable tungsten electrode to create an arc, while a separate filler rod is added manually when required. An inert shielding gas — usually pure Argon — protects the weld pool from contamination. The result is a clean, high-quality weld with excellent appearance, which is why TIG is the process of choice for stainless steel, aluminium, titanium and specialist alloys.
This hub guide brings together everything Weldability SIF’s technical team is asked about TIG welding — how the process works, how to choose tungsten, filler rods and shielding gas, when to use AC or DC, how to diagnose defects, and where TIG is used in industry. Each section links to a detailed sub-topic page so you can go as deep as you need.
What is TIG welding and how does it work?
TIG welding forms an electric arc between a tungsten electrode and the workpiece. The tungsten does not melt; instead, it creates the heat needed to melt the parent material, while filler metal is added separately if required. Because the operator controls the torch and the filler rod independently, TIG offers exceptional precision and produces clean welds with excellent control of heat input.
It is slower than MIG welding, but it offers far greater control, making it ideal for applications where weld quality is critical. For a full walk-through of the process — including pulse TIG, walking the cup, torch set-up and the consumables involved — see our guide to how TIG welding works and setting up your torch. If you are choosing the machine itself — weighing up AC/DC, HF start, pulse and other features — our guide to choosing and buying a TIG welder walks through what matters.
AC or DC — choosing the right current
Choosing the correct current type is essential for good penetration, arc stability and weld quality. In short:
- AC (Alternating Current) is used primarily for aluminium and magnesium, because it helps remove the oxide layer during welding.
- DC (Direct Current) is used for steels, stainless steel, copper, titanium and most other metals.
Our AC vs DC TIG welding guide explains the difference in full and covers how to set your amperage for the material and thickness in front of you.
Choosing the right tungsten electrode
The correct tungsten depends on the material and the current type. Blue (2% Lanthanated) tungsten is widely regarded as the best all-round choice because it performs well on both AC and DC. Grey (Ceriated) tungsten suits lower-current welding, and White (Zirconiated) tungsten is often used for AC aluminium work. Correct preparation — including how you sharpen the tip — has a direct effect on arc stability.
Our TIG tungsten electrode guide covers every colour code, how to sharpen tungsten correctly, and how to solve common problems such as contamination, balling and arc wander.
Choosing the right TIG filler rod
The correct TIG rod depends on the material being welded. As a starting point: 308L for 304 stainless steel, 316L for 316 stainless steel, 309L for joining stainless to mild steel, and ER70S-2 for mild steel. Aluminium, cast iron, titanium, copper and nickel alloys each need their own filler metals.
Selecting the right rod ensures compatible mechanical properties, corrosion resistance and weld quality. See our complete TIG filler rod selection guide for a material-by-material breakdown and rod storage advice.
Shielding gas
Pure Argon is the standard shielding gas for most TIG applications because it provides excellent arc stability and clean welds. Helium or Argon/Helium mixtures may be used for thicker materials where additional heat is needed. Typical Argon flow rates and how to avoid both turbulence and contamination are covered in our TIG shielding gas and flow rate guide.
Welding stainless steel with TIG
Stainless steel is one of the most common materials welded with TIG, and it brings its own requirements — particularly back purging to prevent oxidation (known as “sugaring”) on the rear of the weld. Food-grade, pharmaceutical and duplex stainless steels each demand careful preparation, the correct filler and controlled heat input. Our dedicated guide to TIG welding stainless steel covers purging, sugaring, heat tint and hygienic applications.
Welding aluminium and thin sheet
Aluminium requires AC TIG, thorough cleaning and oxide removal, and the correct filler rod. Thin sheet metal, meanwhile, benefits from TIG’s precise control of heat input. See TIG welding aluminium and thin sheet metal for the technique on each.
Diagnosing TIG welding defects
Even with the right kit, problems happen. Porosity, cracking and arc wander all have specific, identifiable causes — most of which come back to cleanliness, gas coverage and consumable preparation. Our TIG welding defects and troubleshooting guide explains what causes each and how to fix it.
Where TIG welding is used
TIG produces exceptionally clean, precise welds, which makes it the preferred process across demanding industries — aerospace, food manufacturing and marine among them. Our guide to TIG welding applications and standards explains why, and which BS EN ISO and AWS standards apply.
Buying TIG equipment and consumables
When it comes to choosing a TIG welder, the right consumables, or a supplier you can rely on, the decision affects weld quality and production downtime. Our guide to buying TIG welders and consumables covers what to look for in a machine and in a supplier.
Related welding processes
TIG is one of several arc welding processes. Compare it with the alternatives via our MIG welding and MMA welding hubs, or — if you are still deciding which process and machine suit the job — see our guide on how to choose a welding machine. You can also browse the full welding consumables range, or review the welding standards and compliance that govern weld quality.