Monday, 7 April 2014

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Development of TIG Welding & Its application

                                     
This process was inven ted to weld Aluminium. Joining of Aluminium is a major problem due to oxide formation & also due to its low melting point. Aluminium has high strength to weight ratio. Now a days this term was replaced by High specific modulus of elasticity.
It means Aluminium & its Alloy become very important due to its application in making aeroplanes etc.

But no one had the solution for it. At that time Union Carbide Company took this complex task to find a way to join the aluminium.

In 1931, Union Carbide invented the technology to weld Aluminium. At that time This process was known as Heli-Arc Process(Because of the use of the helium as a shielding gas).
it was known as TIG welding. But the term GTAW is more appropriate because sometimes other active can also be used with this process.

WHY ALUMINIUM IS SO HARD TO WELD

1. Aluminium oxide surface coating- At higher temperature highly reactive aluminium forms aluminium oxide. It is a refractory material having high melting point. This surface also absorb moisture causes hydrogen porosity in weld.
2. High thermal conductivity-
due to high thermal conductivity Aluminium requires much more heat for welding than steel. While melting temperature of aluminium is halph of steel.
3. High Coefficient of thermal expansion-
It is twice of steel. It causes distortion & cracking in Weld.


GTAW has eliminated some of the difficulties of welding of aluminium.