Titanium rod is a very active metal, and it is very easy to absorb hydrogen in the process of reducing acid corrosion or crevice corrosion in high temperature hydrogen atmosphere or hydrogen atmosphere. When the hydrogen content of titanium reaches 0.008% -0.015%, the metallographic microscope can be used to observe the precipitation of needle-like hydride phase in titanium. As the hydrogen content further increases, the number of hydrides increases, and the volume of hydrides increases. Titanium absorbs hydrogen to form hydrides and causes corrosion damage. There are roughly the following situations:
(1) The surface corrosion is accelerated. If the diffusion rate of hydrogen is slow, and the hydride is mainly concentrated in Chingbiao, the surface hydride will undergo brittle flaking, which will cause corrosion and the weight loss will increase significantly.
(2) Hydrogen-induced cracking. If hydrogen diffuses to the location where the stress field is concentrated under the action of stress to form a hydride, hydrogen-induced cracking will be formed due to the diffusion of the internal microcracks under the action of stress.
(3) Hydrogen embrittlement. If the titanium rod substrate absorbs a large amount of hydrogen from the surface to cause embrittlement, it will cause hydrogen embrittlement of the titanium material itself.
The above three cases, especially the latter two cases, although the accelerated corrosion rate is not observed, it is often the cause of more dangerous potential accidents. Therefore, the destruction of titanium equipment is often more fatal.
Domestic industrial practice has confirmed many cases of hydrogen embrittlement damage of titanium equipment, such as vinyl chloride production plants, urea synthesis towers, and vacuum salt-making one-effect tanks, which have typical examples of hydrogen embrittlement damage. There are more hydrogen embrittlement accidents. Among other forms of corrosion, it is sometimes difficult to distinguish and discriminate. Therefore, it is necessary to conduct more tests and research to analyze the causes of titanium equipment damage. Comprehensive research and industrial practice at home and abroad.