Tungsten inert gas welding (TIG welding)

Tungsten Inert Gas Welding (GTAW/TIG welding) is an arc welding method that uses a non-consumable tungsten electrode. The welding area is shielded from atmospheric contamination by an inert gas (such as argon), and a filler wire (filler metal) is usually used, although this step can be omitted for some self-fusing welds. It is commonly used for welding thin sheets of stainless steel and non-ferrous metals such as aluminum, magnesium, and copper alloys. It has advantages such as stable arc combustion, no spatter, aesthetically pleasing weld formation, and suitability for all-position welding.

Principle
During welding, the arc, which conducts through highly ionized gas (i.e., plasma) and metal vapor, acts as a constant current welding power source, providing energy.
The shielding gas is continuously ejected from the nozzle of the welding torch, forming a protective layer around the arc to isolate it from the air, protecting the electrode, the weld pool, and the adjacent heat-affected zone, thus forming a high-quality welded joint.
Features
Advantages:
The welding process is stable, and the arc energy parameters can be precisely controlled.
The welding quality is good; argon does not dissolve in liquid metal and does not react chemically with the metal.
Suitable for thin sheet welding, all-position welding, and single-sided welding with double-sided formation without backing.
There is no slag in the weld area, allowing the welder to clearly see the weld pool and the weld formation process.
Disadvantages:
Poor wind resistance; for small side winds, the distance between the nozzle and the workpiece needs to be reduced, and the shielding gas flow rate increased; for strong side winds, wind protection measures must be taken.
High requirements for workpiece cleaning; oil and rust must be strictly removed from the workpiece before welding.
Low productivity; low welding speed and low production efficiency.
Applications
Currently, tungsten inert gas welding is widely used in the welding of various industrial structural metals, and is used in industries such as aircraft manufacturing, nuclear energy, chemical industry, textiles, and power plant boiler engineering.

Development
After the discovery of the short-pulse arc by Humphry Davy in 1800 and the continuous arc by Vasily Petrov in 1802, arc welding developed slowly.
Russell Meredith of Northrop Aircraft Corporation perfected this process in 1941 and named it Heliarc. Over the following decades, development continued, and Linde developed water-cooled torches, which helped prevent overheating during high-current welding.