What is TIG Welding Process or Gas Tungsten Arc Welding (GTAW) -

In TIG Welding Process, TIG stands for Tungsten Inert Gas. TIG is also known as Gas Tungsten Arc Welding (GTAW). It is a process that uses a non-consumable tungsten electrode to form the weld. Generally, it uses filler metal but in some autogenous weld, it does not require it. To protect the weld area from atmospheric contamination, helium or argon is used as a shielding gas. A constant-current welding power supply is used to produce the arc between the electrode and the workpiece.

Most commonly TIG or Gas Tungsten Arc Welding (GTAW) is used to weld thin sections of stainless steel, magnesium, aluminum, and copper alloys. But it can weld all types of metals. This type of welding process allows the operator better control over the weld as compared with Shielded Metal Arc Welding (SMAW) and Gas Metal Arc Welding (GMAW). It is a complex welding process and not easy to master. It requires a lot of hard work and practice to master.

Working Principle of TIG Welding

In the TIG Welding process, an arc is produced in between the non-consumable tungsten electrode and the workpiece which is to be joined. The arc produced creates an intense heat that melts the two metal pieces and fuses them together to form a strong weld by the use of filler metal. The weld so formed exhibits similar properties to the base metal. A shielding gas environment is used to prevent the weld from atmospheric contamination.

Main Equipment

The main equipment used in the TIG welding process is:

1. Welding torch
2. Non-consumable tungsten electrode
3. A constant-current welding power supply
4. A shielding gas ( helium or argon) source

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Working of TIG Welding

In the TIG welding process or Gas Tungsten Arc Welding, the welding torch is connected to a constant current welding power supply and shielding gas source.
With the help of the constant current supply, the electric arc is produced between the electrode and two metal workpieces which are to be joined.
A filler metal is used to join the two metal pieces together. As the spark is struck, the filler metal is inserted in the cavity, and due to intense heat, the filler metal melts and fills the cavity between the two metal pieces and forms a strong weld.
A shielding gas (He or Ar) is used to protect the weld from atmospheric contaminations. As the arc is produced, simultaneously the shielding gas also starts to spread near the weld area and avoids the weld to combine with atmospheric air and protect it from contaminations.
The welding is performed by a highly-skilled operator. The operator has better control over the weld. He can use both hands to control heat generated and filler metal. From one hand he controls the arc produced and with the other hand he controls the feed of filler metal.

Advantages of TIG WElding

Almost all metals can be welded by this technique. But most commonly it is used to weld stainless steel, Al, Mg, and Cu alloys.
It allows better control over the weld. This is because the operator uses both the hand to perform the operation, one hand to control the arc and other to control the feed of filler metal.
The welds formed are highly resistant to corrosion.
Welds thin metal sheets.
Produces good quality welds with precision.
It is a clean process because of less emission of fumes, sparks, spatter and smoke.
It is suitable for work in any position.
It offers greater visibility during the operation due to less emission of smoke and fumes.

Disadvantages of TIG

It is a complex process and difficult to master.
It is not portable and hence suitable for welding shops only.
It is a slower welding process as compared with other welding processes.

Application

The TIG welding process is used in aerospace industries, used to weld thin metal sheets, especially non-ferrous metals.
It is used to manufacture of space vehicles, in bicycle industries to weld small diameter and thin wall tubing.
It is often used to make root or first-pass welds for piping of various sizes.
It is used in maintenance and repair work.