WT20:
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.
WC20:
2% ceriated tungsten electrodes (AWS classification EWCe-2) contain a minimum of 97.30% tungsten and 1.80 to 2.20% cerium. These electrodes perform best in DC welding at low current settings but can be used proficiently in AC or DC processes. With its excellent arc starts at low amperages, ceriated tungsten has become popular in such applications as orbital tube and pipe manufacturing, thin sheet metal work or jobs where small and delicate parts are welded. Like thorium, it is best used to weld carbon and stainless steels, nickel alloys and titanium, making it an obvious replacement for 2% thoriated electrodes. Ceriated tungsten features slightly different electrical characteristics than thorium but most operators won’t be able to tell the difference. Using ceriated electrodes at higher amperages is not recommended. In these situations, the oxides will migrate quickly to the heat at the tip, removing the oxide content and nullifying its process benefits.
WL15:
1.5% lanthanated tungsten electrodes (AWS classification EWLa-1.5) have excellent arc starting, low-burn-off rate, good arc stability and excellent re-ignition characteristics—many of the same advantages as ceriated electrodes. 1.5% lanthanated electrodes also closely resemble the conductivity characteristics of 2% thoriated tungsten, meaning, in some cases, it can replace 2% thoriated without having to make significant welding program changes. 1.5% lanthanated tungsten electrodes are ideal if you want to optimize your welding capabilities. Lanthanated electrodes work well on AC or DC electrode negative with a pointed end or they can be balled for use with AC sine wave power sources. The lanthana is dispersed evenly throughout the entire length of the electrode during manufacturing. It also maintains a sharpened point well, which is an advantage for welding steel and stainless steel on DC or the AC from squarewave power sources. Unlike thoriated tungsten, these electrodes are suitable for AC welding and, like ceriated electrodes, allow for the arc to be started and maintained at lower voltages. AC Compared to pure tungsten, the addition of 1.5% lanthana increases the maximum carrying capacity by approximately 50% for a given size electrode.
WZ8:
Zirconiated tungsten electrode is the most commonly used in alternating current welding,which contains a small amount of Zirconium oxide. It’s electron work is 2.5eV-3.0eV. Zirconiated tungsten electron performs well, and it is easier to start arc than pure tungsten. Arc stability. It can also prevent and control pollution well. Current-carrying capacity is quite good as well. The biggest characteristic of this electron is that its top can keep globular to reduce the seepage of tungsten in the high load current and it also has good corrosion resistance. The superior performance of zirconiated tungsten electron cannot be replaced by other electron.
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.
WY20:
Yttrium tungsten electrode contains 1.8%-2.2% Yttria which its electron function of 2.8eV-3.2eV.
When used in welding, Yttriated Tungsten is primarily used in military and aviation industry with narrow arc beam, high compressing strength, highest welding penetration at medium and high current. Its superior performance also recommends used in the welding of high strength titanium bearing components, as well as high-temperature jet engine components using a single crystal or coarse grained materials, intermetallic compounds, ceramic or metal matrix composites and other new materials.
Therefor they are mainly used in military industry and the aerospace industry.
WP:
Pure tungsten electrode is the earliest use of electrodes in TIG welding. It contains tungsten content minimum 99.5%, without other impurities.
Pure tungsten electrode is only as welding electrode under the condition of AC or resistance welding electrode. It can clean surface of base metal, welded ball become tapering when heating. This shape provides a good and balanced wave form for AC welding.
Pure tungsten electrode has a very high electron output, low vapor pressure, low resistance, good conductivity, thermal expansion, high elastic modulus bright. Therefore, stable arc at low currents, even as low below the 5A. It also does the welding aluminum, magnesium and other.
But the emission of electron demands high voltage and high no-load voltage of welding machine. The tungsten electrode is burned apparently if it works in the high current for a long time. The end may drop into molten pool after melting, which will bring the tungsten into the welding gap. So, it’s just used for welding some black metal or welding the unimportant parts.
Sign in 
