Tungsten Inert Gas TIG welding

Tungsten Inert Gas TIG welding

Introduction

Tungsten Inert Gas (TIG) welding also known as gas tungsten arc welding (GTAW) is a type of welding process that joins two pieces of metals using a non-consumable tungsten electrode. An inert gas is supplied to the welding torch to shield the joining metals from oxidation or contamination and forming defects. TIG welding uses a non-consumable tungsten electrode to produce the weld. TIG welding is a highly skilled method that is used to weld a variety of metals, including aluminum, stainless steel, and mild steel.

In TIG welding, an arc is struck between the tungsten electrode and the metal being welded, which heats the metal and melts it, creating a weld pool. The welder uses a filler metal if needed, and a shielding gas to protect the weld pool from contamination. The weld pool is protected by an inert gas like argon.

TIG Welding Process

The welding torch has inert gas flows along the welding arc. A tungsten electrode is assembled within the welding torch, which has a higher melting point than most metals. In TIG welding, the arc is formed between a pointed tungsten electrode and the welding parts in presence of inert shielding gas (such as argon or helium). The small intense arc provided by the pointed electrode is ideal for high-quality and precision welding. In the TIG welding process, the welder does not have to balance the heat input from the arc as the metal as the electrode is non-consumable.

History of TIG Welding

Its history belongs to the 1940s when TIG welding became popular to weld stainless steel and non-ferrous materials like aluminum, magnesium, and copper alloys. Before that it was difficult welding these metals as these metals react rapidly with the air, resulting in porous, dross-filled welds. In process of TIG welding,  inert gas is used as shielding gas, it protects the weld area and electrode from oxidation and atmospheric contamination.

Shielding Inset Gases

TIG welding process is a better replacement for simple gas or arc welding process as it protects the welding area from atmospheric gases. these atmospheric gases like nitrogen and oxygen after contamination result in fusion defects, porosity, and weld metal embrittlement. The shielding gas is selected based on the material to be welded, joint design, and weld product’s final appearance. Argon or helium (or a mixture of the two) are mostly used inert gases used in TIG welding. Argon has varying arc length that helps in prevents defects in the weld. Argon shielding produces high weld quality and a good appearance of the final product. Whereas helium shielding gas is used to increase the weld penetration in a joint to increase the welding speed. Sometimes the mixture of two (helium and argon) is used to get the benefits of both. sometimes argon-hydrogen and argon-nitrogen are used in special cases. TIG welding has become easy to produce high-quality aluminum welding products for structural applications. 

Materials Used in TIG Welding

The materials used as base materials of TIG welding are; Aluminum, Brass, Bronze, Carbon steel, Copper, Gold, Magnesium, mild steel, Nickel, stainless steel, Titanium steel, and alloys of these materials. TIG welding process the electrode must have the correct diameter and applied amperage. The process of TIG welding changes with the change of material used. The changes range from the size of the electrode diameter down to the electric arc applied in the materials. Keep in mind that lowering the current, the smaller the tip angle and the diameter of the electrode. Another important mechanical tool used in TIG welding is a welding torch that is specialized in melting and fusing metals. It has two types; the first is air-cooled TIG torches used for thin-walled metals and general purposes, second is water-cooled TIG torches used for bigger projects. TIG welding requires a stable and consistent current input as a power source. It could be Alternating Current (AC) or Direct Current (DC) based on the type of material used and type of the welding. 

Non-Consumable Tungsten Electrode

Non-Consumable Tungsten Electrode is used in TIG welding.  Tungsten has a melting temperature of up to 3422°C, which is very high compared to other metals (i.e., stainless steel having melting points ranging from 1400°C to 1530°C). Tungsten has excellent properties of electrical conductivity without being consumed. Sometimes, erosion occurs on the tip during the shielded metal arc welding process. Tungsten electrodes show betterment in properties depending on the weld type. here is the list of these electrodes with their properties:

1) Pure Tungsten Electrodes( green electrodes) have good arc stability when using AC current. It is used for light metals. They are the cheapest and are applied for general-purpose tasks.

2) Thoriated Electrodes (1% thorium yellow electrodes; 2% red electrodes; 3% purple electrodes) They have a high current carrying capacity and they maintain the shape of the tip longer.

3) Lanthaned Electrodes (1% lanthanum black electrodes, 1.5% gold electrodes, 2% blue electrodes) These are non-radioactive electrodes alloyed with lanthanum oxide. They provide excellent arc stability properties with low erosion rates.

4) Ceriated Electrodes (2% cerium grey electrodes)These are also non-radioactive electrodes alloyed with cerium oxide. They have great arc starting but less current capacity.

5) Zirconiated Electrodes (0.7-0.9% zirconium white electrodes, 0.15-0.5% brown electrodes) – These electrodes combine tungsten with zirconium oxide and have a high resistance to contamination and longer electrode life. 

6) Cerium lanthanum Electrodes (pink electrodes) – A combination of ceriated and lanthaned electrodes providing simplified arc ignition with a long life span.

MIG vs TIG Welding

Gas Tungsten Arc Welding (GTAW), or what is commonly referred to as Tungsten Inert Gas (TIG) Welding, is a manual feed process: the operator is feeding the filler metal into the molten metal puddle. But in the TIG process, the filler metal is not the electrode. TIG welding is clean and smooth but can be difficult to master. It’s a good idea to learn MIG welding first and go for MIG welding which is much easier to learn because of the automated process. TIG welding does not produce a spatter during welding, which makes it cleaner and more appealing to the automotive and motorcycle industries and to artists who would like their welds to be a part of the overall look of the piece. The operator has much more control over all the components than other systems.

Advantages and Disadvantages of TIG Welding

TIG welding is commonly used in a variety of industries, including aerospace, nuclear, and medical, for welding high-quality and precise components.

One of the key advantages of TIG welding is its precision. The weld can be precisely controlled, which is important for applications where a high-quality, cosmetically pleasing weld is required. TIG welding is also useful for welding thin metal, which can be difficult to weld with other methods.

However, TIG welding also has some disadvantages, one of the biggest beings that it is relatively slow compared to other welding methods. It also requires a higher degree of skill and experience to produce good-quality welds, as the welder must manually control the torch, filler metal, and shielding gas.

FAQs

What is the purpose of inert gas used in TIG?

The purpose of inert gas used in TIG (Tungsten Inert Gas) welding is to shield the weld pool from the surrounding atmosphere, which prevents oxidation and contamination of the weld. This creates a cleaner, stronger, and more visually appealing weld.

Which gas is used in tungsten inert gas TIG welding?

The most commonly used gas in TIG welding is argon, but other gases such as helium and a mixture of argon and helium can also be used.

How does the Tungsten Inert Gas TIG process work?

The Tungsten Inert Gas (TIG) process works by heating the metal to be welded with a tungsten electrode that is not consumed in the process, creating an electric arc between the electrode and the workpiece. The inert gas is then directed at the weld pool to shield it from the surrounding atmosphere. The welder then adds filler metal manually to the weld pool as needed.

Why tungsten is used in TIG welding?

Tungsten is used in TIG welding because it is a very heat-resistant metal that can withstand the high temperatures of the electric arc without melting. It also has a low thermal expansion coefficient, which helps to maintain a stable arc.

Can you run TIG without gas?

It is possible to run TIG welding without gas, but it will produce a lower quality weld that is more prone to oxidation and contamination.

How does inert gas affect the welding process?

Inert gas affects the welding process by providing a shield around the weld pool that protects it from the surrounding atmosphere. This helps to prevent oxidation and contamination of the weld, which results in a cleaner, stronger, and more visually appealing weld.

Why tungsten is used at high temperature?

Tungsten is used at high temperatures because it is a very heat-resistant metal that can withstand the high temperatures of the electric arc without melting.

What is the main purpose of tungsten?

The main purpose of tungsten is to be used as a heat-resistant electrode in TIG welding, and also in other applications such as electric lamps, heat-resistant alloys, and other electrical and electronic applications.

Why is tungsten only used?

Tungsten is only used in TIG welding because of its high melting point, high thermal conductivity, and low thermal expansion coefficient, making it the most suitable material to use as an electrode in TIG welding.

Conclusion

TIG welding is preferred over other types of welding as it has many advantages over other methods. The TIG welding process, is a versatile process, you can use the process to weld in all welding positions and it has a wide range of amperage and heat control, thus it can be used to weld all thicknesses and all types of metal. It provides excellent results with accurate and good-looking weld beads with penetration. It is the best method for welding aluminum and magnesium alloys and metals like stainless steel. It offers higher quality welds compared to other welding types. Its use has become popular in industries. it has the ability to be easily automated. 

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