English
Choosing one of the six commonly available tungsten electrodes is a crucial first step in successful gas tungsten arc welding (GTAW). In addition, tip preparation is critical. The electrode choices are pure tungsten, 2 percent thoriated, 2 percent ceriated, 1.5 percent lanthanated, zirconiated, and rare earth. The end preparations are balled, pointed, and truncated.
Tungsten is a rare metallic element used for manufacturing gas tungsten arc welding (GTAW) electrodes. The GTAW process relies on tungsten's hardness and high-temperature resistance to carry the welding current to the arc. Tungsten has the highest melting point of any metal, 3,410 degrees Celsius.
These nonconsumable electrodes come in a variety of sizes and lengths and are composed of either pure tungsten or an alloy of tungsten and other rare-earth elements and oxides. Choosing an electrode for GTAW depends on the base material type and thickness and whether you weld with alternating current (AC) or direct current (DC). Which one of three end preparations you choose, balled, pointed, or truncated, also is crucial in optimizing the results and preventing contamination and rework.
Each electrode is color-coded to eliminate confusion over its type. The color appears at the tip of the electrode.
Pure Tungsten (Color Code: Green)
Pure tungsten electrodes (AWS classification EWP) contain 99.50 percent tungsten, have the highest consumption rate of all electrodes, and typically are less expensive than their alloyed counterparts.
These electrodes form a clean, balled tip when heated and provide great arc stability for AC welding with a balanced wave. Pure tungsten also provides good arc stability for AC sine wave welding, especially on aluminum and magnesium. It is not typically used for DC welding because it does not provide the strong arc starts associated with thoriated or ceriated electrodes.
