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

TIG welding is undoubtedly the most versatile process. With this method, it is possible to weld the widest variety of materials, even those that are difficult or reactive.

Inert gas TIG welding is also best for thin materials, thanks to its low heat input, which prevents material burn-through. It is therefore most commonly used in the welding of aluminum and its alloys.

How does TIG welding work? In this method, voltage is applied to the tungsten electrode via a current-carrying wire coming from the power supply. The tungsten electrode is heat resistant, so it does not burn during welding.

The biggest advantages of this welding method are the possibility to use alternating current, thigh joint quality, a stable welding arc between the electrode and the material to be welded, the possibility to weld in all positions and the welding of workpieces with different thickness ranges.

The disadvantages of TIG welding include a slower welding process, low productivity, a relatively expensive torch and the need for a highly skilled operator.

TIG welding – how does it work?

Starting with the basics, TIG welding is a method of welding with a non-consumable tungsten electrode in a shield of inert gases such as argon, helium or mixtures of these. In most cases, however, the shielding gas that welders use in this method is argon.

The resulting welding arc between the electrode and the material melts our base material. In addition, there is no need for additional material, but if we choose to feed it (the filler material is in the form of 1-meter long rods with a suitable diameter) it must be added manually.

The energy required for arc ignition and maintenance is supplied by a unidirectional (direct or pulsed) welding source – so-called DC TIG or alternating current – so-called AC TIG.

Direct current with negative polarity on the electrode is used for welding almost all metals except aluminum, magnesium and their alloys.

As far as positive polarity is concerned, in TIG welding it is not used in practice due to the fact that about 70% of the heat is released at the electrode, which may cause its premature melting.

Aluminium, magnesium and their alloys are welded with alternating current so as to remove any oxides from the metal surface that are difficult to fuse.

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

TIG welding is regarded as the most difficult manual welding method and is therefore not recommended for beginners. Unlike the shielded gas MIG MAG method, it requires a different technique and coordination.

The main difference between MIG and TIG welding is the electrode used to create the arc and the current source.

MIG welding uses solid welding wire, which is fed into the weld automatically by the wire feeder, while TIG welding uses a non-consumable electrode – the welding arc is generated at this electrode.

TIG welding sometimes also uses a manual filler rod.

TIG welding thus involves the generation of an electric arc using an electrode that, unlike MIG MAG welding, is not consumed during the process.

Tungsten electrode for TIG welding

TIG welding is otherwise known as welding with a tungsten electrode – that is, a rod placed in a ceramic nozzle in the welding gun. Around the electrode is a shielding gas nozzle.

It is the part of the holder that directly affects the quality of the whole process, so its proper selection is very important. The classification of welding electrodes depends on the composition and type of oxides present in the electrode. We can distinguish between :

• tungsten welding electrodes – made of pure tungsten
• torium welding electrodes – with the addition of thorium oxides
• lanthanum welding electrodes – with the addition of lanthanum
• cerium welding electrodes – with cerium added
• Zirconium welding electrodes – with the addition of zirconium

To make it easier for the welder to choose the right electrode, they are colour-coded. Below is an overview of the most popular electrodes with a description of their use.

Green tungsten electrodes

These are the only electrodes made of pure tungsten, designed for welding aluminum, magnesium and their alloys, used in AC welding.

Red tungsten electrodes

A thoriated electrode containing 98% tungsten and 2% thorium oxide. It is the most widely used electrode in TIG welding due to its long life, good ignition and stable arc during welding. It is also very versatile and can be used for DC welding (with negative polarity) of stainless steels, nickel, titanium, copper and AC welding of thin aluminum components.

Yellow tungsten electrodes

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

Purple tungsten electrodes

Tungsten electrode (98.5% tungsten, 1.75% lanthanum oxide, 0.095% cerium oxide). Recommended for low to medium welding current due to its excellent arc ignition, used for welding steel, stainless steel, copper and brass.

Grey tungsten electrodes

Cerium electrodes containing 98% tungsten and 2% cerium. Similar in application and properties to thoriated electrode. Can be welded with direct current DC and alternating current AC. Used for orbital welding of pipes, welding of thin sheets. They are a replacement for green electrodes. Suitable for welding high-alloyed steels, unalloyed steels, aluminum, titanium, nickel, copper, magnesium and its alloys.

White tungsten electrodes

Zirconium electrodes contain 99.10% tungsten and 0.15-0.40% zirconium. They are ideal for AC welding, retain the spherical shape of the tip, have high resistance to contamination, and form a very stable arc. Used for welding aluminum and magnesium alloys.

TIG welding – electrode diameter selection

In addition to the type of electrode itself, it is also important to select the to select the correct appropriate electrode diameter:

• 1.0 mm – DC (A) 5–80; AC (A) 10–80
• 1.6 mm – DC (A) 60–140; AC (A) 15–90
• 2,4 mm current DC (A) 130–220; AC (A) 20–140
• 3,2 mm current DC (A) 220–340; AC (A) 30–200
• 4,0 mm current DC (A) 330–350; AC (A) 40–350

TIG welding – how to set up the welder?

We perform the TIG welding process with DC using negative polarity on the electrode to prevent excessive heating of the base material and the torch.

We use AC for welding aluminium, magnesium and their alloys, this type of welding provides greater arc stability and process control.

A common modern TIG feature is pulse welding. This allows adjustment of power, frequency, and pulse duty cycle. This makes it possible to weld thin materials, avoiding overheating and enabling better control over weld shape and arc focus. Filler metal is optional in TIG welding.

The main parameter to set on the machine is current intensity. It should match material thickness, electrode size, and welding position. Amperage affects penetration depth and weld width. Note that higher current increases the electrode tip temperature.

What gas for TIG welding?

The most common gas is argon or an argon–helium mix. These inert gases prevent unwanted reactions with the molten pool and heated metal.

The shielding gases protect the weld pool and consumable electrode from atmospheric contamination. Typical flow rates range from 8 to 16 liters/min depending on current and gas type.

The final key step is to properly clean the workpiece edges to ensure process stability.

TIG welding delivers exceptionally clean, high-quality welds, often without filler metal. The minimal spatter and excellent process control allow welding in all positions, manually or mechanised. This is why it’s often referred to as “clean welding.”