Kathy Stielsa

The “TIG” in TIG welding stands for Tungsten Inert Gas. But before it was named so, it was called “Heliarc” because of the helium that was dominantly used when the process was invented. But then someone discovered that argon worked better and so it was called “TIG” because inert gas could refer to either helium or argon.

Later, it was again discovered that small additions of hydrogen worked well for some metals. The word “inert” then no longer held true and so it was renamed. So nowadays, the technical term for what used to be called “TIG” and “Hiliarc” is Gas Tungsten Arc Welding or “GTAW”.

TIG welding, however, is difficult to use compare to the other arc welding processes. It is required to use both hands where the torch is held in one hand and the filter rod in the other. Often times, a foot pedal amperage control is used which makes it more difficult.

The TIG torch can either be water or air cooled. It is designed to provide shielding gas and welding current through a tungsten electrode. A ceramic nozzle directs the shielding gas to the weld puddle and internal copper parts like the collet and the collet body holds the electrode in place. Then, the tungsten electrode is sharpened for applications where the arc needs to be pinpointed for very low amperage.

The heat melts the metal and makes the weld puddle comes from the arc that is created between the tungsten electrode and the work piece. Argon, helium or a mixture of both shields the arc. For some particular alloys, hydrogen is added in small percentages to improve the way the puddle flows. The arc is very smooth and quiet and clean when DC current is used. But when the TIG welding machine is set on Alternating current, it is slightly noisier but still clean and smooth.

Almost any metal can be welded by TIG. The most popular are carbon and low alloy steels like 1010 carbon and 4130 chromoly steels, Stainless steels like 304,321, and 17-7ph, inconel 718 Nickel alloy and Hastelloy X, 6061 and 5052 Aluminum alloys, az31b Magnesium alloys, Titanium alloys like 6a14v and the ones that are commercially pure, Stellite 6b and 1605 Cobalt alloys, copper alloys like Nibral bronze and pure copper and a whole lot more.

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