Views:24 Author:Site Editor Publish Time: 2017-08-01 Origin:Site
1.Pure Tungsten electrode
Pure tungsten electrodes (AWS classification EWP) contain 99.50% tungsten, have the highest consumption rate of all electrodes and are typically less expensive than “alloyed” counterparts.
These electrodes form a clean, 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, especially on aluminum and magnesium, but is not typically used for DC welding (it does not provide as strong of arc starts as thoriated or ceriated electrodes).
2% thoriated tungsten electrodes (AWS classification EWTh-2) contain a minimum of 97.30% tungsten and 1.70 to 2.20% thorium. They are the most commonly used electrodes today and are preferred for their longevity and ease of use. Thorium increases the electron emission qualities of the electrode, which improves arc starts and allows for a higher current carrying capacity. This electrode operates far below its melting temperature, which results in a considerably lower rate of consumption and eliminates arc wandering for greater stability. It also features a lower level of weld contamination than other electrodes.
Unlike pure tungsten, these electrodes are only for specialty type AC welding (thin gauge aluminum or materials less than .060-in.), but they are exceptional for DC electrode negative or straight polarity on carbon and stainless steel, nickel and titanium applications.
During manufacturing, thorium is evenly dispersed throughout the electrode. This evenness allows the electrode to maintain a sharpened edge—the ideal electrode shape for welding thin steel. Sharpening the electrode’s point, however, should be done with great care. Thorium is radioactive; therefore, you must always follow manufacture’s warnings, instructions and the MSDS (Material Safety Data Sheet) for its use.
3.Zirconiated tungsten electrode
Zirconiated tungsten electrodes (AWS classification EWZr-1) contain a minimum of 99.10% tungsten and 15 to 40% zirconium. A Zirconiated tungsten electrode produces an extremely stable arc and resists tungsten spitting. It is ideal for AC welding as it retains a balled tip and has a high resistance to contamination. Its current carrying capability is equal to or greater than thoriated tungsten. Under no circumstances is zirconiated recommended for DC welding.