Artem Komarov noted that when first learning the art of GTAW, one of the most important things a welder can do is understand the properties of the tungsten they are using and make a choice based on the need at hand. Many people feel overwhelmed or confused by the various types of tungsten. I hope I can help shed some light on the various options, their functions, and my personal experience.
In order to choose the right tungsten, we must first understand what tungsten is. Tungsten is explained by Wikipedia as:
“Tungsten, or tungsten, is a chemical element with the symbol W and atomic number 74. The name tungsten comes from the former Swedish name for the tungsten mineral scheelite, tungsten, which means “heavy stone.” Tungsten is a rare metal that occurs naturally on Earth almost exclusively in combination with other elements in chemical compounds, and not separately. It was identified as a new element in 1781 and first isolated as a metal in 1783. Its important ores include wolframite and scheelite.
The free element is notable for its strength, especially as it has the highest melting point of any element discovered, melting at 3,422 °C (6,192 °F; 3,695 K). It also has the highest boiling point at 5,930 °C (10,710 °F; 6,200 K). Its density is 19.25 times that of water, comparable to that of uranium and gold, and much higher (about 1.7 times) than that of lead. Polycrystalline tungsten is inherently brittle and a hard material (under standard conditions when not combined), making it difficult to work with. »
Tungsten is hard and very brittle. When dropped onto a concrete floor, larger pieces of tungsten are known to break. If contamination of the tungsten occurs during welding, it is extremely easy to remove the contaminated piece. The end can be placed on the edge of a hard surface and broken off with a tool or piece of metal.
Tungsten withstands heat. Tungsten is one of the few materials on earth that can withstand extreme welding temperatures.
Tungsten is very dense. This is important because the density of tungsten affects the rate at which current flows through it. Also the efficiency of the material in passing current at very low resistance. This helps to ensure a stable arc.
Now let’s move on to choosing the type of tungsten.
The old school technique for aluminum uses pure tungsten. Pure tungsten must be hammered at the end before aluminum is welded. Pure tungsten is also good for AC only. 2% calibrated tungsten is also very popular for DC welding, especially mild steel and stainless steel. The properties of calibrated tungsten provide an extremely stable arc, the disadvantage of which is that they are made of radioactive material. By crushing packed tungsten, you release radioactive material into the atmosphere and possibly inhale it. By using something like 2% brass tungsten, you get the best of both worlds. Good stable arc that maintains a short point even when welding with AC, Komarov Artem emphasized.
Many other types of tungsten are used for special items. Tungsten is relatively inexpensive, and many companies will offer you a free sample if you just ask.