Common titanium grades (with national material standards)
TA1 (Grade2) Industrial Pure Titanium
TA2 (Grade3) Industrial Pure Titanium
TA9 (Grade11) Ti-0.2Pd
TA10 (Grade12) Ti-0.3Mo-0.8Ni
TC4 (AB-1) Ti-6Al-4V
Corrosion resistance of titanium
Titanium is a metal with a strong tendency to passivate. It can quickly form a stable oxidative protective film in air and in an oxidizing or neutral aqueous solution. Even if the film is damaged for some reason, it can be quickly and automatically recovered. Therefore, titanium has excellent corrosion resistance in an oxidizing or neutral medium.
Due to the large passivation properties of titanium, in many cases contact with dissimilar metals does not accelerate corrosion and 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 are accelerated and titanium is not affected. In hydrochloric acid, when titanium is in contact with low carbon steel, the new surface hydrogen is generated on the surface of titanium, which destroys the oxide film of titanium, which not only causes hydrogen embrittlement of titanium, but also accelerates corrosion of titanium. This may be due to the high hydrogen concentration of titanium. Caused by activity.
The iron content in titanium has an effect on the corrosion resistance of some media. The reason for the increase of iron is that, in addition to the raw materials, it is often that the iron contaminated during welding penetrates into the weld bead, so that the local iron content in the weld bead is increased. Corrosion has non-uniform properties. When iron is used to support the titanium equipment, iron contamination on the iron-titanium contact surface is almost inevitable in the corrosion of the iron contamination zone, especially in the presence of hydrogen. When the titanium oxide film on the contaminated surface is mechanically damaged, hydrogen permeates into the metal, and hydrogen diffuses correspondingly according to conditions such as temperature and pressure, which causes titanium to have different degrees of hydrogen embrittlement. Therefore titanium is used in medium temperature and medium pressure and hydrogen containing systems to avoid surface iron contamination.
Under normal circumstances, titanium does not pitting.
Titanium also has corrosion and fatigue stability.
Titanium has good crevice corrosion resistance, especially Ti-0.3Mo-0.8Ni and Ti-0.2Pd alloys. Therefore, Ti-0.3Mo-0.8Ni and Ti-0.2Pd alloys are widely used in sealing surface materials for container equipment to solve Corrosion of the sealing surface of the equipment.