Tungsten electrode is used for TIG welding, in fact, it's a tungsten alloy bar made of tungsten doped with rare earths such as cerium: about 0.3%-5%, thorium, lanthanum, yttrium and zirconium through the method of powder metallurgy, and then through the pressure processing, diameter is from 0.25 to 6.4mm, the standard length is from 75 to 600, and the most commonly using specification is the diameter of 1, 1.6, 2.4 and 3.2.
The shape of electrode end is an important factor for TIG, when DCSP is used, the electrode end should be grinded into a tip shape, and the tip angle is changed along with the application range, electrode diameter, and the welding current, and the narrow joint requires a smaller tip angle, when you weld the very thin material, it needs the minimum electrode with low current and needle like. The appropriate grounding electrode can ensure the easy arc starting, good arc stability and proper welding bead width. When the welding is used the AC power supply, you don't need to grind the electrode end. Because when you use the appropriate welding current, the electrode end will form a half spherical shape, if increasing the welding current, the electric end will become a bulb shape, and it is very possible to be melted. In this case, it will pollute the molten gold.
With the development and the expansion application of tungsten electrode, the research on tungsten electrode is also deeper and deeper. In plasma arc welding, cutting and non melting TIG welding, in the past, we always adopted the thorium tungsten electrode, but due to radioactive effects of thorium (the radiation dose up to 3.60 x 105 Curie /kg) can harm the human health and pollute the environment.  Therefore, the cerium tungsten electrode whose cerium oxide content is about 2 ~ 4% is instead of thorium tungsten electrode. In DCEN TIG welding, cerium tungsten electrode has easy arc starting, electrode erosion quantity is little, the allowing welding current density is larger than thorium tungsten; while in the AC argon arc welding, burning loss quantity of cerium tungsten electrode is larger than the thorium tungsten electrode, and the allowed welding current range of cerium tungsten electrode is less than the thorium tungsten electrode.
The operation of thorium tungsten electrode is very simple, even in the overload current, and its operation is also very well, there are still many people using this material, it is regarded as a part of high quality welding. Even so, people still gradually turned to other types of tungsten electrode, such as tungsten cerium and lanthanum tungsten. Because thorium oxide in thorium tungsten electrode generated small radiation, which makes part of the welding persons don't want to close to them.