What is TIG (GTAW) Welding, it Applications & How it Works?

Tungsten inert gas welding (TIG), also known as gas tungsten arc welding, uses an electric arc struck between a non-consumable tungsten alloy electrode and the metal workpiece to be welded. The non-consumable tungsten electrode delivers the current to the welding arc.

An inert gas such as argon protects and cools the tungsten and weld puddle. This welding process is precise and versatile and is used to produce high-quality welds and protect the welding area from atmospheric contamination with an inert gas, such as argon.

Well, in this reading, we’ll explore what TIG welding is, its applications, parts, equipment, diagram, and how it works. We’ll also explore the advantages and disadvantages of TIG welding.

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Table of Contents

What is TIG Welding?

GTAW, or tungsten inert gas (TIG) welding, is a welding process that uses a non-consumable tungsten electrode to produce welds. An inert shielding gas (argon or helium) protects it from oxidation or atmospheric contamination. We commonly use TIG welding to join thin sections of stainless steel and non-ferrous metals such as aluminum, magnesium, and copper alloys.

GTAW allows greater control over the weld than competing processes but is more complex and slower than other welding techniques. Plasma arc welding, a related process, uses a different torch for a more focused welding arc.

TIG welding is a precision process used for creating high-quality welds on thin materials. It uses a non-consumable tungsten electrode for arc stability and allows for the addition of filler material.

TIG welding is versatile and requires skill in controlling heat and filler material, resulting in clean, aesthetically pleasing welds.

Applications of TIG Welding

TIG welding is a widely used process in various industries, particularly in aerospace, automotive, repair, and art fields. It is particularly effective in welding thin workpieces, especially nonferrous metals, and it is suitable for small-diameter, thin-wall tubing.

TIG welding is particularly useful in repairing tools and dies made of aluminum and magnesium. The process is particularly useful in welding refractory, sheet, and reactive materials.

Aerospace, which constructs aircraft and spacecraft, and the automotive industry, which prioritizes safe and secure construction, find TIG welding particularly useful. Various repair applications, like repairing children’s toys and aluminum tools, also utilize TIG welding.

TIG Welding Parts and Equipment

The major components in GTAW or TIG welding include a power source, a non-consumable tungsten electrode, an inert gas supply, and a welding Torch.

Power Source

TIG welding requires a constant, drooping power source for stable heat input. Alternating current (AC) and direct current (DC) power sources are available for different material types and weld outputs. AC welding maintains heat without overheating base materials like aluminum and magnesium.

DC power electrode negative pinpoints energy flow to targeted areas, appealing to all metals except aluminum and magnesium. TIG welding rarely uses DC power electrode positives due to their rapid heat input. Shiny oxides on the weld pool’s surface can reveal cleaning action.

Non-Consumable Tungsten Electrode

Due to their high melting temperature, tungsten electrodes play a crucial role in welding, providing excellent electrical conductivity without consuming energy. These electrodes can be alloyed to improve their properties, depending on the weld type.

Pure tungsten electrodes (green) provide stable arcs when using AC, while thoriated electrodes (1% thorium, yellow; 2%, red; 3%, purple) can handle more current and keep their tip shape for a longer time.

Lanthanized electrodes (1% lanthanum black, 1.5% gold, 2% blue) are safe metal mixtures that include lanthanum oxide, known for their great ability to maintain an arc and low wear over time.

Cerium lanthanum electrodes (2% cerium gray) have great arc starting but less current capacity. Zirconiated electrodes (0.7-0.9% zirconium white, 0.15-0.5% brown) combine tungsten with zirconium oxide, offering high resistance to contamination and longer electrode life.

Cerium lanthanum electrodes (pink) combine ceriated and lanthanated electrodes, offering simplified arc ignition and a long life span.

Inert Gas Supply

The welding process involves the use of a TIG torch and an inert gas, such as argon, to protect the weld pool from contamination and impurities.

As the metals melt and fuse, this gas flow plays a crucial role in preventing oxidation and impurities from the atmosphere. Other combinations of hydrogen and argon or helium and argon are also used depending on factors like metals to be welded and welding speed.

Welding Torch

A welding torch is a mechanical tool used for melting and fusing metals. There are two types: air-cooled TIG torches, which have only one gas input and are prone to overheating, and water-cooled TIG torches, which have a gas input and output for water lines, ideal for larger projects requiring rapid cooling. However, these torches require a water cooler system to be installed.

Diagram of TIG welding

How Does TIG Welding Work?

The working of tungsten inert gas welding is less complex and can be easily understood. The principle of operation is similar to MIG welding; an electrical current generates heat that melts the base metal and bonding materials. It then cools down and forms a solid joint. Despite the similarities, there is still a significant difference between the welding processes.

The TIG welding process involves adjusting the machine to the right settings, such as current and voltage, and setting the correct pressure for inert gas in the supply tank.

Modify the TIG torch in accordance with the project requirements, selecting an electrode with the correct diameter and a TIG collet. Clean protective gear is crucial for clear vision during welds.

After preparing, welding the metals together is essential, considering factors like arc length, travel speed, and torch angle. We can run TIG welds without filler material, melting the base metals, but if necessary, we can use filler rods or metal coils. TIG cold welding, despite its popularity, lacks fusion due to reduced heat input and is ineffective in creating strong, permanent joints.

Differences between MIG and TIG welding

TIG welding is a unique welding process that uses a non-consumable electrode and separate filler material, unlike MIG welding, which uses a continuous, consumable wire electrode. Due to its low heat input, TIG welding commonly joins pipes and thin materials, preserving the microstructure of metals.

We prefer it for thicker materials due to its lower cost and high weld speeds. TIG welding rarely creates spatter and requires light polishing to remove discoloration. It is preferred when the workpiece is not coated or painted, such as in welding stainless steel and aluminum.

The use of filler metal is optional for TIG welding, but it requires both hands and controlling the heat input with the pedal simultaneously. Most welders start out as MIG operators and transition later into TIG welding. TIG welding is not a plug-and-play process, but it is highly versatile due to its adjustable features, such as amperage flow, pulse amount, AC/DC output, and inert gas flow.

The table below shows the difference between TIG and MIG welding:

MIG Welding	TIG Welding
Metal inert gas (MIG) welding utilizes a consumable electrode that is continuously fed into the welding zone from a wire pool.	Tungsten inert gas (TIG) welding utilizes a non-consumable electrode (so it remains static and intact during welding).
The electrode itself melts down to supply the necessary filler metal required to fill the root gap between base metals. So the electrode acts as filler metal (no additional filler is required).	If necessary, we additionally supply the filler metal by feeding a small-diameter filler rod into the arc. Therefore, we supply the filler metal separately.
The composition of electrode metal is selected based on the parent metal. Usually, the metallurgical composition of electrode metal is similar to that of base metal.	An electrode is always made of tungsten with a small proportion of other alloying elements (like thorium).
It is suitable for homogeneous welding. It cannot be carried out in autogenous mode welding, as filler is applied inherently.	It is particularly suitable for autogenous mode welding. However, you can also use it for homogeneous or heterogeneous modes by adding additional filler.
The electrode-cum-filler for MIG welding comes in the form of a small-diameter (0.5–2 mm) and very long (several hundred meters) wire that is wound in a wire pool.	TIG welding filler typically comes in the form of a small-diameter (1–3 mm) and short-length (60–180 mm) rod.
The filler electrode’s very large length allows for extended feeding without the need for replacement.	Due to the short length, frequent replacement of filler is required. This procedure interrupts the welding process unintentionally.
MIG welding is commonly carried out either in AC or in DCEP polarity so that electrodes can be melted and deposited at a faster rate.	TIG welding is commonly carried out in either AC or DCEN polarity to increase electrode life.
The filler deposition rate is very high, so the process is highly productive.	The filler deposition rate is low. Therefore, the process is not very efficient.
MIG welding usually produces a spatter. This condition causes the loss of costly filler metal.	TIG welding is mostly free from spatter.
The quality and appearance of weld beads are not excellent.	It can easily produce defect-free, reliable joints with a good appearance.
It does not lead to a tungsten inclusion defect.	TIG welding sometimes leads to a tungsten inclusion defect (occurring when a melted/broken part of the tungsten electrode gets embedded into the weld bead).

Advantages and Disadvantages of TIG Welding

Tungsten inert gas TIG Welding is a highly efficient method for joining metals, offering advantages such as the ability to work with a wide variety of metals, producing high-quality and precise welds, and being done automatically or manually.

However, TIG welding has some disadvantages, such as its inability to work with thicker sheets of metal, the need for skilled workers, potential eye damage from high-intensity lights, high costs, and a slow process.

Despite these drawbacks, TIG welding remains a crucial method for welding critical joints and producing high-quality, high-purity welds. Its advantages also make it suitable for various applications, making it a versatile and cost-effective option for welding different metals.

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How Does Tungsten Inert Gas (TIG) Welding Works?