What is TIG welding?
The designation TIG comes from the USA and is an abbreviation of Tungsten Inert Gas. Tungsten - also called wolfram - is a metal with a fusion point of more than 3300°C, which means more than double the fusion point of the metals which are usually welded.
Inert Gas is the same as inactive gas, which means a type of gas that will not combine with other elements. In Germany this method is called WIG welding, the W meaning wolfram. TIG welding is the international, standardised designation for this welding method. According to DS/EN 24063 this welding process has number 141.
The principle of TIG welding is an electric arc welding process in which the fusion energy is produced by an electric arc burning between the workpiece and the tungsten electrode. During the welding process the electrode, the arc and the weld pool are protected against the damaging effects of the atmospheric air by an inert shielding gas. By means of a gas nozzle the shielding gas is lead to the welding zone where it replaces the atmospheric air.
TIG welding differs from the other arc welding processes by the fact that the electrode is not consumed like the electrodes in other processes such as MIG/MAG and MMA. If it is necessary to use filler material, it is added either manually or automatically as a bare wire.
The TIG arc
As mentioned before, the fusion energy in TIG welding is produced in the arc burning between the tungsten electrode and the workpiece. The wire feeding can be done manually or mechanically.
In DC TIG (Direct Current) welding, the tungsten electrode is usually connected to negative polarity and the workpiece to positive polarity. According to the theory of electrons the negatively charged electrons and positively charged ions will migrate when the arc is ignited. AC TIG (Alternating Current) is characterised by the fact that the voltage changes polarity a certain number of times, usually 100 times per second.
- It provides a concentrated heating of the workpiece.
- It provides an effective protection of the weld pool by an inert shielding gas.
- It can be independent of filler material.
- The filler materials do not need to be finely prepared if only the alloying is all right.
- There is no need for after treatment of the weld as no slag or spatter are produced.
- Places of difficult access can be welded.
TIG welding is typically applied in industries requiring high-quality welding, such as:
- Offshore industry
- Combined heat and power plants
- Petrochemical industry
- Food industry
- Chemical industry
- Nuclear industry
- Materials for TIG welding
- Welding of thin materials in stainless steels
- Nickel alloys