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2. Select the Right Tungsten
At the center of the GTAW process is the tungsten electrode, a nonconsumable metallic element that carries the welding current to the arc. Knowing your tungsten is key. The thickness of the material being welded and welding amperage are two important factors to consider when making the selection.
Tungsten electrodes come in a variety of diameters, typically from 0.020 to 5⁄32 in., and are available in industry-standard lengths of 7 in. Custom lengths are also available but tend to cost more. The electrodes are composed of either pure tungsten or a hybrid of tungsten and other rare-earth elements and oxides. To eliminate confusion about the various types, each electrode is color-coded at the tip to denote its type.
Depending on the material being welded, you can choose from pure tungsten—typically used for AC welding of aluminum on older transformer-designed machines—or ceriated, lanthanated, rare earth, and thoriated. Each option has characteristics suited for certain applications and materials. Ceriated tungsten is a good general tungsten that can be used with most everything, while thoriated and lanthanated tungsten are good options for welding stainless steel and exotic materials.
Thoriated tungsten provides many benefits because of its high ability to emit electrons, which allows the arc to come off the tip of the tungsten. However, note that thoriated tungsten contains low levels of radioactivity, so be sure to follow the manufacturer’s warnings, instructions, and the Material Safety Data Sheet (MSDS).
