Numerical Interpretation of Hydrogen Thermal Desorption Spectra for Iron with Hydrogen-Enhanced Strain-Induced Vacancies

Abstract

We obtained thermal desorption spectra of hydrogen for a small-size iron specimen to which strain was applied during charging with hydrogen atoms. In the spectra, a shoulder-shaped peak in the high-temperature side was enhanced compared with the spectra of the specimen to which only strain was applied. We also observed that the peak almost disappeared by aging processes at ≥ 373 K. Then, assuming that the shoulder-shaped peak results from hydrogen atoms released by vacancies, we simulated the thermal desorption spectra using a model incorporating the behavior of vacancies and vacancy clusters. The model considered up to vacancy cluster $${{V_9}}$$ V 9 , which is composed of nine vacancies, and employed the parameters based on atomistic calculations, including the H trapping energy of vacancies and vacancy clusters that we estimated using the molecular static calculation. As a result, we revealed that the model could, on the whole, reproduce the experimental spectra, except two characteristic differences, and also the dependence of the spectra on the aging temperature. By examining the cause of the differences, the possibilities that the diffusion of clusters of $${V_2}$$ V 2 and $${V_3}$$ V 3 is slower than the model and that vacancy clusters are generated by applying strain and H charging concurrently were indicated.

Modeling hydrogen dragging by mobile dislocations in finite element simulations

“…Last, the TTD framework has been shown to be flexible enough to allow the inclusion of the dislocation breakaway from their Cottrell atmosphere and illustrated on a loading pulse. This work paths the way to further development in hydrogen-metal interactions, as trapping and dragging by vacancy or vacancy clusters, based on the same approach (see, e.g., [34]).…”

“…This is also the case for any other trap kind, as, e.g., vacancies and vacancy clusters. It is worth, however, to point out the work of Ebihara et al, which have modelled vacancy mobility and clustering [34], but without any consideration on trapped hydrogen dragging. This paper aims to propose a generalization of the hydrogen transport equation, accounting for both trap mobility and hydrogen dragging by mobile traps.…”

Identification of the Fracture Process in Gas Pipeline Steel Based on the Analysis of AE Signals

“…Mechanical loads appear due to the internal pressure of gas and external loads, including permanent, cyclical and accidental loads [ 2 , 3 ]. The action of corrosion [ 4 ] and hydrogen on the pipeline metal, in turn, is caused by the gas conveyed in the pipeline [ 5 , 6 , 7 ]. The long-term flow of the above-mentioned media causes specific changes in the microstructure of the pipe steel—changes in phase composition and coagulation of precipitates, the appearance of microcracks and fractures caused by corrosion and additional pressure at the tips of local micro defects caused by the action of hydrogen [ 8 , 9 , 10 , 11 ].…”

Evaluation and Analysis Method of Hydrogen Embrittlement

“…a) 水 素 添 加 と 同 時 に ひ ず み を 与 え た 場 合 (H+strain)とひずみのみを与えた場合(strain)の昇 温脱離曲線，(b)H+strain の試料を異なる温度で時効し た場合の昇温脱離曲線42) …”