Tungsten electrode
At present, ceriated tungsten electrode, which has no radioactive pollution, is a green environmental protection product. It can start arc easily with a small current, and the arc current is relatively small. Under the condition of low current direct current, ceriated tungsten electrode is very popular. However, there is a point that it is not as good as thorium tungsten in burning resistance, and the consumption is faster. If the consumption is fast, the investment will be large, and the cost will be high if the investment is large. This is what many manufacturers who use tungsten argon arc welding do not want to see.
Therefore, it can be seen that lanthanated tungsten electrode is the most suitable substitute for thorium tungsten electrode at present. At least in the current technical conditions, this is the most suitable. It has the most similar performance to thorium tungsten electrode. Even in the case of medium and small current, the arc performance and burn resistance of the electrode are better than that of the thorium tungsten electrode. Moreover, the lanthanated tungsten electrode has no radioactivity, high endurance current and minimum burning loss rate.
Thorium tungsten electrode contains 1-1.2% thorium oxide. Thorium is a radioactive material, which is affected by radiation during welding and contact with thorium tungsten rod.
Radiation acts on the human body in two forms:
One is external irradiation
Second, through the respiratory and digestive system into the body to produce internal irradiation. A large number of investigations and measurements of shielded argon arc welding and plasma arc welding have proved that their radioactive hazard is small, because the consumption of thorium tungsten electrode rod is only 100-200 mg per day, and the radiation dose is very small, which has little impact on human body.
But there are two things to note:
Firstly, when welding in the container, the ventilation is not smooth, and the radioactive particles in the dust may exceed the hygienic standard;
The other is that the concentration of radioactive aerosol and dust can reach or even exceed the hygienic standard when grinding thorium tungsten rod and the place where thorium tungsten rod exists. Radioactive substances can cause chronic radiation diseases, mainly manifested in the general functional state weakened, can see obvious weakness, resistance to infectious diseases significantly reduced, weight loss and other symptoms. Thorium tungsten electrode contains thorium oxide (Th02 or thorium oxide), which is the most commonly used tungsten electrode and has become a standard to judge the quality of other tungsten electrodes. However, due to the low-level radioactive hazard of the tungsten electrode, many users have switched to other options. Generally speaking, 2% thorium tungsten electrode is a good tungsten electrode, which has the lowest work output and works well even under overload voltage. The performance of thorium tungsten electrode is better than that of pure tungsten electrode in many aspects. Thorium oxide provides a current carrying capacity of about 20% higher than that of pure tungsten, with a longer service life and helps to prevent contamination during welding.
When thorium tungsten electrode is used, arc striking is easier and the arc is more stable than pure tungsten electrode or zirconium tungsten electrode. Both thorium tungsten electrode (ewth – 1) and thorium tungsten electrode (ewth – 2) can be used for DCEN. Thorium tungsten electrode is usually used as DC negative electrode or positive electrode of carbon steel, stainless steel, nickel alloy and titanium alloy. They have good performance and can be well welded even under overload current.
