The results of ab initio modeling of the interaction between hydrogen and the ferrite/cementite interface in pearlitic steel are presented for three crystallographic orientations: Bagaryatskii, Isaichev, and Pitsch–Petch. It was found that phase boundaries act as effective traps for hydrogen, with a binding energy of up to –0.30 eV, in agreement with experimental data reported in the literature. The minimum hydrogen solution energy and maximum binding energy are observed at the interface, whereas hydrogen binding in bulk ferrite and cementite is weaker. Structural analysis, including interatomic distances, magnetic moments, and interstitial geometry, reveals a strong correlation between crystal lattice structure and hydrogen trapping ability. The interface with Isaichev orientation provides the strongest hydrogen trapping due to favorable structural alignment of adjacent crystal lattices. The obtained results were used to develop a thermodynamic model of ferrite–cementite interaction; calculations of hydrogen absorption based on the derived trapping energies show that fine lamellar mixtures of ferrite and cementite with interlamellar spacing below 0.1 μm exhibit significant hydrogen adsorption capacity at temperatures below 400 K.
Verkhovykh et al. (Mon,) studied this question.