TIG welding – how to set up your welder, choose the right electrode, and select the appropriate shielding gas

TIG welding is widely regarded as the most versatile welding process. It allows for welding a broad range of materials — including heavy and challenging alloys.

Thanks to its low heat input, TIG welding with inert gas is ideal for thin materials, minimising the risk of burn-through. This is why it is commonly used for welding aluminium.

How does TIG welding work? In TIG welding, voltage is applied to a tungsten electrode through a current-carrying lead from the power source. The tungsten electrode is heat-resistant and does not melt during the welding process.

Key advantages of TIG welding include the ability to use alternating current, superior joint quality, a stable arc between the electrode and the workpiece, welding in all positions, and suitability for materials of varying thicknesses.

Its disadvantages include relatively slow welding speed, lower productivity, the high cost of the welding torch, and the need for a skilled operator.

Table of contents

TIG welding – how does it work?

To start with the basics: TIG welding is a process that uses a non-consumable tungsten electrode within a shield of inert gases such as argon, helium, or their mixtures. Argon is the most commonly used shielding gas in this method.

The welding arc formed between the electrode and the workpiece melts the base material. No filler material is required, but if one is used (typically in the form of 1-metre rods of suitable diameter), it must be fed manually.

The arc energy is supplied by either a direct current (DC) or alternating current (AC) welding source — referred to as DC TIG or AC TIG, respectively.

DC with negative electrode polarity is used for welding most metals, except aluminium, magnesium, and their alloys.

Positive polarity is not used in TIG welding, as approximately 70% of the heat is concentrated at the electrode, causing it to melt.

Aluminium, magnesium, and their alloys are welded using alternating current to remove oxide layers that are difficult to fuse.

TIG welding vs. MIG MAG welding – which method is better?

TIG welding is considered the most difficult manual welding method and is generally not recommended for beginners. Unlike the MIG/MAG process, TIG welding follows a different welding pattern.

The primary difference between MIG and TIG welding lies in the type of electrode and the way the arc is created.

MIG welding uses a continuously fed solid wire, while TIG welding uses a non-consumable tungsten electrode to generate the arc.

In TIG welding, a filler rod may be added manually if needed.

TIG welding involves generating an arc using a non-consumable electrode — unlike MIG/MAG welding, where the electrode melts during the process.

Tungsten electrode for TIG welding

TIG welding is also known as tungsten electrode welding — the electrode is a tungsten rod housed in a ceramic nozzle, surrounded by a shielding gas outlet.

This part of the torch plays a crucial role in weld quality, so selecting the right electrode is essential.

Tungsten electrodes are classified based on their composition and the type of oxides they contain. The main types include:

pure tungsten electrodes — made of 100% tungsten
thoriated electrodes — containing thorium oxide
lanthanated electrodes — containing lanthanum oxide
ceriated electrodes — containing cerium oxide
zirconiated electrodes — containing zirconium oxide

To make electrode selection easier, each type is colour-coded. Below are the most popular types and their typical applications.

Green tungsten electrodes

These are pure tungsten electrodes, used primarily for AC welding of aluminium, magnesium, and their alloys.

Red tungsten electrodes

These thoriated electrodes contain 98% tungsten and 2% thorium oxide. They are the most widely used in TIG welding thanks to their long lifespan, easy arc ignition, and stable arc. They are suitable for DC welding (negative polarity) of stainless steel, nickel, titanium, and copper, as well as for AC welding of thin aluminium components.

Yellow tungsten electrodes

The lanthanum electrode contains 98.5% tungsten and 1.5% lanthanum oxide. A versatile electrode with high arc stability, good tacking properties and recommended for high current welding. Suitable for DC and AC welding. Suitable for welding of high alloyed and unalloyed steels, aluminium, titanium, copper and magnesium alloys.

Blue tungsten electrodes

Lanthanum electrode containing 98% tungsten and 2% lanthanum oxide. A versatile electrode for AC and DC welding processes and plasma welding, recommended for automated welding. Used for unalloyed steels, high-alloyed steels, aluminium, titanium, copper and magnesium alloys.

Purple tungsten electrodes

Tungsten electrode composed of 98.5% tungsten, 1.75% lanthanum oxide, and 0.095% cerium oxide. Recommended for low to medium current applications due to excellent arc ignition. Used for welding steel, stainless steel, copper, and brass.

Grey tungsten electrodes

Ceriated electrodes containing 98% tungsten and 2% cerium oxide. Similar in performance to thoriated electrodes. Suitable for both DC and AC welding. Commonly used for orbital pipe welding and thin sheet applications. Considered a replacement for green electrodes. Compatible with high-alloyed and unalloyed steels, aluminium, titanium, nickel, copper, magnesium, and their alloys.

White tungsten electrodes

Zirconiated electrodes consist of 99.10% tungsten and 0.15–0.40% zirconium. Ideal for AC welding, they retain a spherical tip, resist contamination, and provide a stable arc. Used for welding aluminium and magnesium alloys.

TIG welding – electrode diameter selection

In addition to the electrode type, selecting the correct electrode diameter is also essential:

1.0 mm – DC: 5–80 A; AC: 10–80 A
1.6 mm – DC: 60–140 A; AC: 15–90 A
2.4 mm – DC: 130–220 A; AC: 20–140 A
3.2 mm – DC: 220–340 A; AC: 30–200 A
4.0 mm – DC: 330–350 A; AC: 40–350 A

TIG welding – how to set up the welding machine?

TIG welding can be performed using DC current, with negative polarity on the electrode to avoid excessive heating of the base material and torch.

AC current is used for welding aluminium, magnesium, and their alloys, providing better arc stability and weld pool control.

Modern TIG welders often support pulse welding, a widely used feature today. This function allows the adjustment of power, frequency, and duty cycle, enabling effective welding of thin sheets by avoiding overheating, and providing greater control over arc focus and weld shape. TIG welding can be performed with or without filler material, depending on the application.

The primary setting on a TIG welding machine is the current. It must be selected based on material thickness, electrode diameter, and welding position. Amperage determines weld depth and width. Keep in mind: higher current increases the temperature at the tungsten tip.

What gas for TIG welding?

The most commonly used shielding gases in TIG welding are pure argon or argon-helium mixtures.

These inert (non-reactive) gases prevent chemical reactions with the weld pool and hot workpiece.

Shielding gases protect the weld pool and the electrode from atmospheric contamination. Typical shielding gas flow rates range from 8 to 16 litres per minute, depending on the current and gas type.

A crucial step before TIG welding is thoroughly cleaning the edges of the workpiece — essential for weld quality and stability.

TIG welding enables extremely clean, high-quality welds — often without the use of filler metal.

Minimal spatter and excellent process control make TIG welding suitable for all positions — both manual and automated. That’s why TIG is often referred to as “clean welding.”