ungsten inert gas (TIG) welding is a high quality low deposition rate welding process. It uses an arc struck between a nonconsumable tungsten electrode and the work to fuse the base material and thereby form a welded joint.
The TIG welding process may be used on thin sheet material without the addition of a filler metal (autogenous TIG welding).
Alternatively, when working on thicker sheet or when joining dissimilar materials, a separate wire filler metal is added into the arc region where it is melted and directed by the welder into the molten weld pool.
The weld pool, the hot tungsten electrode and the melting filler wire are protected from atmosphere by a shield of inert or slightly reducing gas.
Argon is often used although productivity and quality benefits can be gained by using mixtures of argon and helium or argon and hydrogen (see the table of recommended GeminiTM gases over the page).
TIG welding is suitable for manual, mechanised and automatic (orbital) operation.
In manual welding, the operator points the tungsten electrode in the direction of welding and uses the arc to melt the base material along the joint,
Double operator AC TIG welding of an aluminium vessel.
ahead of the molten weld pool.
The filler metal is generally added at the leading edge of the advancing weld pool.
Both Direct Current (DC) and
Alternating Current (AC) may be used when TIG welding, the choice depending upon the type of material to be welded.
DC (electrode negative) is used for the following
materials:– carbon steel q copper q stainless steels q nickel alloys q titanium q zirconium.
AC is used for the following materials:– q aluminium and its alloys q magnesium q aluminium bronze. q Non-consumable electrodes Ozone reduction
Electrode diameter to current dia. mm
maximum operating current (A) thoriated DC