TIG welding

TIG Welding or Tungsten Inert Gas Welding

● Intense heat of electric arc produced between a non-consumable tungsten electrode and the material to be welded.

● The shielding gas is obtained from an inert gas (helium, argon, mixture of helium and argon).

● Argon is mostly used because it is a heavier gas and producing better shielding at lower rate.

● The shielding gases displaces the air surrounding the arc and weld pool.

● It prevents the contamination of the weld metal by the oxygen and nitrogen in the air.

● Filler metal may be used, when a filler rod is fed manually in the weld pool.

● Automatic feeding of the filler wire into the TIG arc to speed up the process as developing.

● Automatic feeding of the filler wire into the TIG arc to speed up the process as developing.

● Tungsten is a good welding electrode material due to its high melting point of

6170⁰ C.

● Between the electrode and the work piece by supplying the electric power, the inert gas from the cylinder passes through the nozzle of the welding head around the electrode.

● The inert gas surrounds the arc and protects the weld from atmospheric effects and hence defect free joints are made.

● This process is also called as Gas Tungsten Arc welding [GTAW]. Filler metal may or may not be used.

● When a filler metal is used, it is usually fed manually into the weld pool.

● An electrode used in this process is tungsten it has, high melting point [330°C],

Therefore it will not melt during welding.

● This process is used for welding steel, aluminium, Cast iron, magnesium, Stainless steel, Nickel based alloys, and copper based Alloys and low alloy steel.

● It is also used for the combining of dissimilar metals hard facing and the surfacing of metals.

● This process is used for the metals having thickness less than 6.5 mm.

Advantages:

● The TIG process lends itself applied to the fusion welding of aluminium and it alloys, stainless steels, magnesium alloys, nickel based alloys, copper based alloys, carbon steel, low alloy steels.

● It is also used for weld dissimilar metals, hard facing, and the surfacing of metals.

Disadvantages:

● All joints require proper cleaning before welding as the inert gas does not provide fluxing [cleaning] action.

● The process is slow in operation.

● The cost of the process is high.

Applications:

● Used for welding all metals and alloys of various thickness.

● Extensively used for welding aluminium, stainless steel and titanium.

● Employed for fabrication of missiles, air craft and rockets.

● Also used for fabrication of chemical plant and high pressure steam pipes.

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