Correlation Between Thermal Desorption Spectrum Features and Creep Damage

The analysis of the spectrum features of thermal desorption spectroscopy (TDS) using the desorption-rate profile against temperature is widely applied to investigate the hydrogen kinetics including diffusion and trapping in metallic materials, which is related to hydrogen embrittlement. Recently the TDS spectrum features such as the peak magnitude and the peak area have been used for qualitative assessment of creep damage, although there is still a lack of theoretical understanding on the correlation between TDS spectrum features and creep damage. In this paper, creep voids inducing creep damage are considered as the only kind of hydrogen traps in steels. The relationships between the TDS spectrum features and creep damage of ferritic steels are investigated through parameter analysis of the modified McNabb-Foster model together with the Oriani assumption, which can describe hydrogen evolution during thermal desorption. It is found that the peak area of TDS spectrum is independent of the trap binding energy, and it is proportional to the trap density, demonstrating that it could be a good indicator for creep damage. The creep damage can be characterized as a power-law function of the peak area of TDS spectrum, indicating TDS as a promising semi-destructive characterization method for creep damage of metallic steels.