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Abstract

Hydrogen is a key element in the transition toward sustainable industries but can also cause severe material degradation through hydrogen embrittlement (HE). Trapping hydrogen at microstructural defects is an effective way to mitigate HE, though the trapping efficiency varies depending on each defect’s influence on the hydrogen solution energy. This study explores how different microstructural defects affect hydrogen solution energies in ferritic steels using density functional theory (DFT). Three coincident site lattice (CSL) grain boundaries, Σ3, Σ5, and Σ27, with low, moderate, and high free volumes, are analysed. The effects of segregated alloying elements (Cr, Cu, Ti) and vacancies within these grain boundaries are also examined. To complement the theoretical results, ferritic iron-based model alloys with different chemical compositions and CSL grain boundary fractions were produced. This poster also presents our recent study, “Increasing the content of CSL grain boundaries in ferritic steel through grain boundary engineering,” which provides the experimental basis for generating bcc alloys with higher CSL grain boundary fractions. Finally, the calculated solution energies will be used as input for adsorption models such as Oriani’s theorem to predict thermal desorption spectroscopy (TDS) spectra of model alloys with different compositions and CSL grain boundary fractions.