To those of us who may not be aware, tungsten is an uncommon metallic element that is used in the manufacturing of TIG (or GTAW) electrodes. The TIG electrodes demand the type of hardness and high temperature resistance that tungsten alone can provide. This is because tungsten electrodes are meant to carry the welding current to the arc. It is to be noted that tungsten has an inconceivably high melting point when compared with other metals.
These electrodes come in different sizes and lengths and are available either as pure tungsten or a hybrid of tungsten mixed with other rare earth elements and oxides. Choosing the right electrode depends on the type and thickness of the base material and whether you are going to weld with alternating or direct current.
Please know that pure tungsten electrodes are expected to contain nearly 100% tungsten and have the maximum consumption rate of all electrodes. Tungsten electrodes are strangely less costly than its alloyed counterparts. These electrodes form a balled tip when heated and provide great arc stability for AC welding with balanced wave. Pure tungsten also provides good arc stability for AC sine wave welding – for aluminum and magnesium welding.
Thoriated tungsten electrodes (Color Code: Red) contain a minimum of 97.30% tungsten and balance thorium. These electrodes are the most widely used electrodes and are known for longevity and easy use. Thorium is highly useful in increasing the electron emission qualities of the electrode. Thus, it improves arc starts and enables a higher current carrying capacity. It also results in a lower level of weld contamination than other electrodes.
Ceriated tungsten electrodes (Color Code: Orange) contain a minimum of 97.30% tungsten and balance cerium. These electrodes are known to perform remarkably well in DC welding at low current settings. With its excellent arc starts at low amperages, ceriated tungsten are widely used as orbital tube and pipe manufacturing, thin sheet metal work or jobs where small and delicate parts are welded.
Lanthanated tungsten electrodes (Color Code: Gold) contain a minimum of 97.80% tungsten and balance lanthanum. These electrodes are known for their excellent arc starting as well as arc stability, low-burn-off rate and quick re-ignition capabilities. The fact is, in select cases, LaB6 Cathode electrodes can replace 2% thoriated without having to make significant welding program changes.
Zirconiated tungsten electrodes (Color Code: Brown) contain a minimum of 99.10% tungsten and balance zirconium. Zirconiated tungsten electrode is capable of stable arc and it resists tungsten spitting. The added feature is its current carrying capability which is equal if not more than thoriated tungsten. Zirconiated electrodes are unsuited for DC welding.
Rare earth tungsten electrodes (Color Code: Gray) contain unspecified additions of rare earth oxides or a mixture of different oxides. However, manufacturers will indicate each additive and its percentage on the outer label. Depending on the additives, you can obtain a stable arc in both AC and DC processes as also more longevity.
Finally, it may be said that the arc quality and welding performance you achieve will largely depend on the type and shape of tungsten you use. Each of these six types of tungsten has its own merits and shortcomings. It is therefore critically important you choose the right tungsten appropriate for each application.