Numerical interpretation of thermal desorption spectra of hydrogen from high-carbon ferrite-austenite dual-phase steel

Abstract

The peak in the thermal desorption spectra of hydrogen from a high-carbon ferrite-austenite dual-phase steel shifts to the high-temperature side as the amount of charged hydrogen increases. However, the hydrogen-trapping state and the peak formation process are unclear. We interpreted the spectra by reproducing them using the previously reported model. Introducing a diffusion barrier from the ferrite phase to the austenite phase and excluding hydrogen entering the austenite phase shows that the peak is attributed to the carbide trap site when the amount of charged hydrogen is comparatively small and hydrogen trapped by the interface trap site increasingly influences the peak as the amount of charged hydrogen increases. We also found that the thickness dependence of the peak for the interface trap site could be attributed to a different reason than the conventional diffusion-determining process.