TIG is an acronym for Tungsten Inert Gas, an arc welding process that uses a non-consumable electrode (tungsten), under the protection of inert gas. The welding can take place with or without a filler metal. This technique offers several advantages, including the quickness of its execution, adaptability to any working position, the ease with which the arc can be controlled and thus the regularity of deposits, the regulation of the current within a wide range, and powerful, concentrated heat sources. Thanks to this last characteristic, very thin materials can be welded (as thin as .5mm) in a short amount of time.
This type of welding was initially developed for the aeronautic industry during World War II to replace rivets on aircraft with welding, which weighed less while boasting the same strength. TIG welding has limits to its application due to the impossibility of using elevated currents. TIG cannot be used in continuous currents and direct polarization since the electrons arriving at the anode (the piece being welded) cannot break the oxide.

The result is that the TIG alternating current is the most used. Consisting of a semi-period of waves in which the electrode is positive and breaks the oxide, followed by a semi-period in which the electrode is negative, thus allowing it to rest and not overheat. TIG welded materials can then undergo a manual polishing to buff away the characteristic cord that is left by the process.

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