What does hydrogen desorption mean?

Hydrogen corrosion occurs when hydrogen decomposes into atomic hydrogen and ionized hydrogen at high temperatures, which then penetrate into the steel through the lattice of the base material. Since the rate of penetration into the steel varies depending on temperature and pressure, it is necessary to control the rate of cooling and pressure reduction during shutdown processes. If this rate is too fast, hydrogen won’t have enough time to diffuse out of the base material, leading to stress-induced cracking in the steel. Therefore, it is essential to maintain a constant temperature to allow hydrogen to diffuse out gradually. Furthermore, since there is a surfacing layer inside the reactor, usually made of austenitic stainless steel, the different diffusion rates between the base material and the surfacing layer often lead to the accumulation of hydrogen between them, which in turn causes stress at the interface and results in delamination. However, all of these require a certain incubation period; therefore, during the shutdown period, it is necessary to control the rate of temperature change and also maintain constant temperature and pressure for hydrogen release!

Looking for answers to questions before reading will help you remember the content better~~~ For hydrogenation, it’s still necessary to understand the basic concepts~~~

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