Tungsten Inert Gas (TIG) welding, is an arc welding process that uses a nonconsumable tungsten electrode to produce the weld. The weld area is protected from atmospheric contamination by a shielding gas (usually an inert gas such as argon), and a filler metal is normally used. A constant-current welding power supply produces energy which is conducted across the arc through a column of highly ionized gas and metal vapors known as a plasma. 

 

TIG welding is most commonly used to weld thin sections of stainless steel and non-ferrous metals such as aluminum, magnesium, and copper alloys.  TIG welding is comparatively slower and more complex than other welding techniques but yields stronger, higher quality welds.  TIG welding also allows for dissimilar metals such as copper and mild or stainless steel to be welded together.