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Ebihara, Kenichi; Saito, Kei*; Takai, Kenichi*
Proceedings of 2016 International Hydrogen Conference (IHC 2016); Materials Performance in Hydrogen Environments, p.470 - 477, 2017/00
For understanding hydrogen (H) embrittlement of steels, it is necessary to infer the state that defects trap H in the steels. Thermal desorption spectra of H obtained by the thermal desorption spectrometry (TDS) are used for inferring such a state. Because the thermal desorption spectra include the influence of experimental conditions and hydrogen diffusion as well as information of the defects trapping H, it is necessary to interpret the spectra using the numerical simulation. In the presentation, we determined the detrapping and the trapping rate constants which are necessary for the simulation from the experimental spectra obtained for plate specimens which is so small that H diffusion is ignorable. Then we confirmed that the model using the obtained rate constants can simulate the spectra of larger cylindrical specimens, so that it was found that the rate constant for small specimens can be used for the simulation of the spectra for specimens of different shape or size.
Ebihara, Kenichi; Kaburaki, Hideo; Takai, Kenichi*
no journal, ,
In order to understand the mechanism of hydrogen(H) embrittlement it is necessary to grasp properly the H state in steels. In the thermal desorption analysis, the H state is deduced from thermal desorption spectra which are obtained by measuring hydrogen desorbed from a steel specimen heated at a constant rate. However, because the desorption spectra include the influence of experimental conditions and of initial H distribution as well as information of the H state, the spectra must be interpreted using the numerical simulation. In the presentation, we examined the influence of the initial H distribution, which varies according to experimental conditions, on the specimen size dependence of the method to evaluate the detrapping rate constant from experimental spectra. As a result, though the influence of the initial distribution becomes remarkable when the size is large, its influence was very small in the range less than 2mm for iron and less than 8mm for tempered martensitic steels.
