TIG welding

TIG weldingTIG welding is one of the fusion welding procedures. TIG welding is mainly used for thin sheets made of aluminium and stainless steel, but can also be used for normal steel sheets and plates.

It can be used universally and is characterised by its clean and tidy results. This method produces little spatter and virtually no gases, which is advantageous for the welder’s health. The current required for welding the workpiece is supplied via a tungsten electrode (2). Unlike MIG or MAG welding the electrode does not melt. The welds (5) are very high quality, because the melted metal (4) is protected against oxidation by the supply of a shielding gas (3).

It is supplied directly via the welding head (1). As the electrode does not melt, the filler metal (7) is added manually. In TIG welding the welder can match the current intensity and the quantity of filler metal to the workpiece (6). In TIG welding the filler metal is added continuously or drop by drop. The filler wire remains continuously in the liquid weld pool. This procedure is therefore also called the “pushing method”.

Nikolai Nikolaijewitsch Bernados invented arc welding between 1880 and 1887. In 1881, he demonstrated this procedure for the first time at the Paris exhibition. He generated an arc between a carbon electrode and a workpiece. Later in 1885 he registered this procedure as a patent.

TIG welding was invented in 1946 in the USA. The original name was argon arc welding and it represented a further development of the carbon arc welding procedure.

TIG Welding – Technical information

In TIG welding a differentiation is made between 2 variants. On the one hand, it is welding with direct current, which is the most frequently used type. The tungsten electrode is positioned on the negative pole. This form of welding is used to join alloyed steels as well as non-ferrous metals such as copper or brass. On the other hand it is welding with alternating current. This type of welding is used to join lightweight metals such as aluminium and magnesium, as the oxide layer is broken up. In exceptional cases, however, lightweight metals are also welded with direct current, in which case the electrode is attached to the positive pole. In general, however, it can be stated that each metal suitable for fusion welding procedure can be welded using the WIG procedure.

As tungsten inert gas welding can be used both manually and as an automated process, this procedure is used in very many areas. Large opportunities for its use are found in the aerospace industry, in structural steelwork and railing construction as well as in pipe laying. TIG welding is always used if particularly high weld quality and properties are required. This work can be done using two hands in manual welding. One hand is used to add the filler metal while the other hand holds the welding torch. As the skill requirements are very high, these tasks are only carried out by specialised welders.

Advantages

No slags are produced when the inert gases argon and helium are used. This welding procedures is very fast. This means that the material hardly deforms at all due to the short heat effect. TIG welding can be used in all positions.

Disadvantages

This welding procedure is very susceptible to wind. For this reason, TIG welding cannot be used outdoors. The action of wind can blow the shielding gas away, which then results in increased oxidation of the weld. Such welds are nowhere near as durable as welds welded under shielding gas. Rust must always be removed during the weld preparation.