There are two types of titanium welding materials available. One type directly cuts the titanium strip from the titanium base metal, and uses it as a welding material for titanium after being polished and pickled. The other type is titanium welding wire.
The impurity elements Fe, H, O, N, C in the titanium welding wire are far lower than the content of the titanium base metal of the corresponding brand. This has great benefits for reducing the content of harmful impurities in the weld, improving the corrosion resistance of the weld and improving its mechanical properties. Welding seams are generally weak parts that are prone to problems during use. It is easier to guarantee the quality of using titanium welding wire during welding than using the main titanium rod as the welding material.
In the vacuum salt production, the liquid level fluctuation part of the evaporation tank is to ensure that the inner wall of the tank is flat and smooth, and the welding adopts the structure shown in Figure 2. A non-penetrating welding structure is adopted between the titanium insert and the titanium clad layer. This structure has strict manufacturing requirements, and the weld seam is relatively fragile. In the design, it should be considered that this part is made on the ground at one time and hoisted as a whole, which is conducive to manufacturing and welding. At the same time, the equipment should have sufficient rigidity to prevent the titanium weld from cracking due to the deformation of the equipment during transportation and installation.
Titanium is a metal with excellent corrosion resistance, but it is also a delicate metal. According to relevant information, the cleanliness of the titanium surface and even fingerprints can also affect the welding quality. Iron pollution, improper welding process and welding specifications, and reliable protection without high-purity argon can greatly reduce the corrosion resistance of titanium. In the entire manufacturing process, the operation should be strictly in accordance with the manufacturing regulations of titanium, especially the protection of the titanium surface and the quality of welding, so as not to reduce the excellent corrosion resistance of titanium. The 100% colored flaw detection inspection of titanium welds and titanium inserts, and the reverse ventilation leak detection of titanium cover welds have proved in practice to have a good effect on the inspection of possible cracks, pores and other defects in titanium welds. Color flaw detection and ventilation leak detection should be carried out strictly in accordance with procedures. After the titanium-steel clad plate is compounded, the titanium surface is not pickled, and the titanium surface will inevitably be polluted during the compounding process. In the process of making titanium equipment, although many protective measures have been taken, it is still difficult to make a large area of titanium surface completely pollution-free in practice. After the equipment is finished, it is absolutely necessary to pickle the titanium surface. After the titanium surface of the 300,000-ton vacuum salt production project of Da'an Salt Factory was fully pickled, in addition to the iron contamination inspection, the small holes, cracks and other defects on the surface of the raw materials were also inspected, which helped eliminate the problem before operation.
After nearly ten years of rapid development, the economic benefits of titanium equipment in salt production equipment have been highlighted. A lot of experience has been accumulated in the use of titanium equipment, which undoubtedly creates excellent conditions for the large-scale promotion and application of titanium in the field of vacuum salt production equipment.
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