Classification of tungsten electrodes
Cerium tungsten electrode
Cerium oxide is added to tungsten to produce cerium tungsten electrode.
Cerium tungsten has the following advantages over thorium tungsten
*Non radiation * low melting rate * long welding life * good arcing performance. Therefore, Ce-W is the best substitute for Th-W in low current welding environment.Ce-W electrode is mainly used in low current DC welding. Cerium tungsten has excellent arc starting performance at low current, so it has become the standard of most rail pipe welding equipment manufacturers. In addition, it is also used in other low current applications, such as small parts welding.Cerium tungsten is not suitable for high current applications, because in this condition, the oxide will quickly move to the high heat zone, that is, the top of the electrode welding, which will damage the uniformity of the oxide. Therefore, the above benefits due to the uniform distribution of the oxide will no longer exist.
Lanthanum tungsten electrode
Lanthanum oxide is added into tungsten to produce lanthanum tungsten electrode.
La-w has the following advantages:
*Better mechanical cutting performance * better creep resistance * higher recrystallization temperature * better ductility. At present, la-w electrode is the most popular electrode material in the world, especially the La-W electrode with the content of 1.5% (different from 2.0%).Scientific research shows that 1.5% La-W has the conductivity closest to that of 2.0% W-Th, so the welder can easily replace the electrode without changing the parameters of the equipment.In 1998, there was a famous field test, that is, 2.0% tungsten thorium electrode, 2.0% tungsten cerium electrode and 1.5% lanthanum tungsten electrode provided by two manufacturers were used for welding tasks under the current of 70 A and 150 A and 300 V direct current respectively. The result is that in both cases, 1.5% lanthanum tungsten electrode shows excellent welding performance and low burn rate.La- electrode is also suitable for AC welding task, and its performance is excellent.
Thorium tungsten electrode
Thorium oxide is doped in tungsten to produce thorium tungsten electrode.
Compared with pure tungsten, thorium tungsten has the following characteristics:
*Lower electronic function * higher crystallization temperature * better conductivity * better mechanical cutting performance.Thorium tungsten electrode is a kind of widely used tungsten electrode material. It has better welding performance than pure tungsten, so it is widely used in the field of DC welding.The thorium tungsten electrode is easy to operate and can work well even under overload current.However, people gradually turn their attention to other types of tungsten electrodes, such as tungsten cerium and tungsten lanthanum, not only because of their excellent performance in most applications, but also because they have no radiation damage. Because the thorium oxide in the thorium tungsten electrode produces a small amount of radiation, some welding personnel do not want to get close to them.When using thorium tungsten electrode for welding, it is necessary to keep a good ventilation environment, and the abandoned welding joint should be properly treated.
Zirconium tungsten electrode
Zirconia was doped into tungsten to produce zirconium tungsten electrode.
Like pure tungsten electrode, zirconium tungsten electrode can only be welded in alternating current environment. Zirconium tungsten electrode has good welding performance in AC environment. Especially in the case of high load current, zirconium tungsten electrode shows superior performance, which can not be replaced by other electrodes.During welding, the end of Zr-W electrode can be kept round and spherical to reduce tungsten penetration and has good corrosion resistance.Due to the appearance of other alternative products, the demand of zirconium tungsten electrode will decrease. The main substitute is W-La electrode.
Yttrium tungsten electrode
Yttrium tungsten electrode in welding, the arc beam is slender, compression degree is large, in medium and large current, its penetration is larger, mainly used in military industry and aerospace industry. Zirconia was doped into tungsten to produce zirconium tungsten electrode.
Measures to prevent radiation injury
1. The thorium tungsten electrode should have special storage equipment, which should be stored in iron box and installed with exhaust pipe.
2. When welding with airtight hood, the hood should not be opened during operation. In manual operation, the helmet must be worn or other effective measures must be taken.
3. A special grinding wheel shall be provided to grind the thorium tungsten electrode. The grinding machine shall be equipped with dust removal equipment. The grinding debris on the ground of the grinding machine shall be cleaned by wet method frequently and buried deeply.
4. Wear dust mask when grinding thorium tungsten electrode. Wash hands with running water and soap after contacting thorium tungsten electrode, and wash work clothes and gloves frequently.
5. Select reasonable specification during welding and cutting to avoid excessive burning of thorium tungsten electrode.
6. Cerium tungsten electrode or lanthanum tungsten electrode should be used instead of thorium tungsten electrode as far as possible, because the latter two are not radioactive.
