Gas Tungsten Arc Welding: Advantages, Disadvantages & Applications

What is Gas Tungsten Arc Welding?

Gas tungsten arc welding (GTAW) is an electric arc welding process which uses a non-consumable tungsten electrode to produce the weld. The gas tungsten arc welding is also known as tungsten inert gas (TIG) welding.

In case of GTAW, the weld area is protected from the atmospheric contamination by a shielding gas. This shielding gas usually an inert gas such as argon. In general, a filler material is also used, although some welds, known as autogenous welds, do not require it.

In this welding process, a constant current welding power supply is used to produce energy which is conducted across the arc through a column of highly ionized gas and metal vapors, known as plasma.

The schematic diagram of a gas tungsten arc welding is shown in the figure below.

Gas tungsten arc welding equipment consists of a welding torch, a welding power supply, a source of inert gas, etc. In the welding process, the filler metal is supplied from a welding wire, it is because the tungsten electrode is not consumed in this welding process. A constant and stable arc gap is maintained at a constant current level. A gas shield of argon (or any other inert gas) protects the electrode and the molten metal and provides the required arc characteristics.

The GTAW is most commonly used arc welding process to weld thin sections of stainless steel and non-ferrous metals like aluminium, copper alloys, etc. The gas tungsten arc welding is comparatively more complex and difficult to master and also, it is significantly slower than most other electric welding techniques.

Advantages of Gas Tungsten Arc Welding

The chief advantages of the gas tungsten arc welding are given as follows −

  • No flux is used in gas tungsten arc welding. Therefore, there is no flux entrapment in the weld bead.

  • The welds made with gas tungsten arc welding are stronger and more ductile than those of other metal arc welding processes.

  • TIG welds are more corrosion resistant.

  • With the GTAW, a wide variety of joint design can be used because, no flux is required.

  • The gas tungsten arc welding provides protection to the weld from the atmospheric contamination.

  • With the tungsten inert-gas welding, there is no weld splatter or sparks that could damage the surface of the base metal.

  • Gas tungsten arc welding is suitable for all welding positions viz. horizontal, vertical and overhead

  • Gas tungsten arc welding is suitable for welding of food or medicine containers where deposit of any decaying organic matter could be extremely harmful.

Disadvantages of Gas Tungsten Arc Welding

The disadvantages of gas tungsten arc welding or tungsten inert gas welding are as follows −

  • Relatively slower welding speed than other welding processes.

  • In case of TIG welding process, the concentrations of shielding gas may build up.

  • It produces brighter ultraviolet rays than other welding processes.

  • It has lower filler metal deposition rates.

Applications of Gas Tungsten Arc Welding

Some of the applications of gas tungsten arc welding are given below −

  • Gas tungsten welding is used for welding of articles of aluminium and its alloys.

  • GTAW is also used for welding of stainless steel, magnesium alloys, nickel base alloys, carbon steel, low alloy steels and copper base alloys, etc.

  • The tungsten inert gas (TIG) welding process is also used for welding of dissimilar metals.

  • It is also used for hard facing and the surfacing of metals.