Effect of alloy element on hydrogen-induced grain boundary embrittlement in BCC iron

The strength enhancement usually increases its susceptibility to hydrogen (H) embrittlement in steel materials. However, the atomic-level mechanisms of solutes influence hydrogen behavior at grain boundaries (GBs) remain incompletely understood. To address this gap, first-principles calculation was utilized to analyze the interactions between 25 different solutes and H at the Σ5 (310) GB of body-centered cubic (BCC) iron. This study focused on how these solutes affect H segregation and their role in mitigating H-induced GB embrittlement, thereby elucidating the mechanisms of solute-H interactions at GBs. The results show that elements such as Cr, Mn, Ni, Zr, Nb, Mo, W, and Re not only reduce H segregation at GBs, but also effectively alleviate H-induced GB embrittlement. Furthermore, first-principles calculation tensile tests (FPCTT) simulations were employed to investigate the effect of the H segregation behavior at GB on uniaxial tensile strain, shedding light on the fundamental processes of bond break and crack initiation at GBs. The present work provides deeper insights into the mechanisms of GB embrittlement and offers strategic guidance for designing steel materials with enhanced H embrittlement resistance.