Tungsten electrode is a non-melting electrode used in tungsten electrode argon arc welding. Commonly used tungsten electrode materials are: pure tungsten electrode, thorium tungsten electrode and cerium tungsten electrode.

The density of pure tungsten electrode is 19.3g/cm3, the melting point is 3387 °C, the boiling point is 5900 °C, and the strength is 850~1100Mpa. It was the earliest electrode material used, but a high electric field strength was required to emit electrons. Therefore, the argon arc welding machine is required to have a high no-load voltage. Pure tungsten electrode is seriously burned and has not been used much.

Tated tungsten electrode is composed of less than 2% thorium oxide added to the tungsten electrode. Thorium tungsten electrode has high thermal electron emission ability and melt resistance, especially when using alternating current, the allowable current value is 1/3 higher than that of pure tungsten electrode of the same diameter, and the no-load voltage can be significantly reduced. The dust of thorium tungsten electrode has trace radioactivity, so care should be taken to protect it when grinding the electrode and welding. Thorium tungsten electrodes are typically used in DC negative electrodes or positive electrodes such as carbon, stainless steel, nickel alloys, titanium alloys, etc. They work well and can work well even under overloaded currents. Thorium tungsten electrodes are commonly used in the field of direct current welding, while pure tungsten electrodes are used for alternating current welding.

Cerium tungsten electrode is made by adding 2% cerium oxide to tungsten electrode, which has more advantages than thorium tungsten electrode, such as slender arc beam, heat concentration, current density can be increased by 5%~8%, and low burn-out rate, long service life, easy arc starting, less radioactive dose, etc. The product is characterized by excellent arc initiation performance under low current conditions, and small arc current. Therefore, it is commonly used for the welding of pipes, stainless steel products and small precision parts. At low current DC conditions or electrode diameters below 2.0 mm, cerium-tungsten electrodes are the preferred alternative to thorium-tungsten electrodes. The red color is thorium tungsten and the gray color is cerium tungsten. Cerium tungsten electrodes have the following advantages over thoriated tungsten electrodes: thoriated tungsten electrodes have slight radiation, and they can only operate at high currents. However, cerium tungsten electrodes are non-radiative welding materials and can operate at low currents. Another chemical property of cerium tungsten electrodes is that they have small cathode spots, pressure drop, and do not burn, so they are the most widely used in argon arc welding.

Thorium tungsten electrode contains 1-1.2% thorium oxide, which is a radioactive substance. During the welding process, radiation acts on the human body in two forms: one is external irradiation, and the other is through the respiratory and digestive systems into the body to cause internal irradiation. From a large number of investigations and measurements of argon arc welding and plasma arc welding, it is proved that their radioactive hazards are small, because the daily consumption of thorium tungsten pole is only 100-200 mg, the radiation dose is very small, and the impact on the human body is not great. However, there are two situations that must be noted: one is that when welding in the container, the ventilation is not smooth, and the radioactive particles in the smoke and dust may exceed the sanitary standard; Second, when grinding thorium-tungsten rods and where thorium-tungsten rods exist, the concentration of radioactive aerosols and radioactive dust can meet or even exceed the health standards. The invasion of radioactive substances into the body can cause chronic radiation sickness, which is mainly manifested in the weakening of the general functional state, obvious weakness and weakness, a significant reduction in resistance to infectious diseases, weight loss and other symptoms.