Medical titanium rod The analysis of characteristic hydrogen embrittlement cases shows that hydrogen embrittlement is localized. Gap corrosion, pitting corrosion, galvanic corrosion, stress corrosion, etc. will cause hydrogen absorption and local hydrogenation of titanium rod.

The manufacturer of medical titanium rod believes that although the causes of crevice corrosion and pitting corrosion are different, their development is based on the principle of blocking the battery. Hydrolysis reaction will occur when corrosion proceeds to a certain stage, resulting in a large amount of H+:

Due to the formation of a large amount of H+, the pH value of solution in the gap or point decreases significantly, reaching 1-1.6, or even 0.7. This will further promote the dissolution of titanium and form the so-called autocatalysis, so that local corrosion develops at a high speed. At the same time, H precipitates in the cathode area, part of which is absorbed by titanium, so it will cause local hydrogenation. Stress corrosion also has a similar situation, so that some scholars believe that stress corrosion is a hydrogen embrittlement phenomenon.

Many cases of hydrogen embrittlement caused by galvanic corrosion have been reported. The contact between titanium and steel in the high-temperature seawater chemical equipment forms a couple, and the connection between the titanium tube of the power station condenser and the copper tube plates forms a couple, which may cause hydrogen absorption of titanium and local hydrogenation due to galvanic corrosion. Hydrogen absorption of titanium in contact with dissimilar metals in degassed salt water and pure water. The potential of titanium decreases after contact with some metals. For example, the potential of titanium in seawater is 0.14V/SCE, which is -0.79V/SCE when it contacts with zinc, and -0.8V/SCE when it contacts with steel in 6% Na solution. Titanium will absorb hydrogen when its potential drops to -0.65-0.7V/SCE after neutralization in seawater and contact with these metals. The results of galvanic corrosion are related to the stable potential, contact area and polarization characteristics of the metals in contact with each other, so it must affect hydrogen absorption.

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