Titanium Application Knowledge
Titanium is a metal with a strong tendency to passivation. It can quickly form a stable oxidizing protective film in the air and in an oxidizing or neutral aqueous solution. Even if the film is damaged for some reason, it can quickly and automatically recover. Therefore, titanium has excellent corrosion resistance in oxidizing and neutral media.
Due to the huge passivation properties of titanium, in many cases, when it comes in contact with dissimilar metals, it does not accelerate the corrosion, but may accelerate the corrosion of dissimilar metals. For example, in a low-concentration non-oxidizing acid, if Pb, Sn, Cu or Monel is contacted with titanium to form a galvanic couple, these materials will corrode faster, and titanium will not be affected. In hydrochloric acid, when titanium is in contact with low-carbon steel, new hydrogen is generated on the surface of titanium, which destroys the titanium oxide film, which not only causes hydrogen embrittlement of titanium, but also accelerates the corrosion of titanium. This may be due to the high degree of hydrogen on titanium. Caused by activity.
The iron content in titanium has an impact on the corrosion resistance of some media. The reason for the increase in iron is that in addition to the raw materials, the contaminated iron penetrates into the weld bead during welding, which increases the local iron content in the weld Time corrosion has a non-uniform nature. When using iron to support titanium equipment, iron contamination on the iron-titanium contact surface is almost unavoidable and accelerated in the iron-contaminated area, especially in the presence of hydrogen. When the titanium oxide film on the contaminated surface is mechanically damaged, hydrogen will penetrate into the metal. According to conditions such as temperature and pressure, hydrogen will diffuse correspondingly, which will cause different degrees of hydrogen embrittlement of titanium. Therefore, titanium should be used in medium temperature and medium pressure and hydrogen-containing systems to avoid surface iron contamination.
