Influence of specimen size on calculation of detrap rate constant in hydrogen thermal desorption analysis; A Study by numerical simulation

Ebihara, Kenichi   ; Kaburaki, Hideo; Takai, Kenichi*

In order to understand the mechanism of hydrogen embrittlement, identifying the state of hydrogen trapped by defects in steels is dispensable. In the identification of the hydrogen trapping state, thermal desorption profiles of hydrogen obtained in the thermal desorption analysis of steel specimens are widely used, and need to be analyzed using the numerical model because they include the effect of the specimen size and the experimental conditions as well as the effect of defects. The prefactor of detrap rate in the model is previously used as a fitting parameter. In the presentation, the influence of specimen size on the identification of the prefactor was examined numerically. As a result, in the specimens of pure iron and martensite steels whose size is larger than 0.3 mm, the accuracy of the identification rapidly drops. In addition, according to the influence of the prefactor on the desorption profile, it is possible to identify the order of magnitude of the prefactor.