Role of carbon on the hydrogen embrittlement of Σ3(112) 110 symmetrical tilt grain boundary ferritic iron

R Budiantono and M Wirmas and WJ Sari and GK Sunnardianto and AG Saputro and MH Mahyuddin, MODELLING AND SIMULATION IN MATERIALS SCIENCE AND ENGINEERING, 33, 085006 (2025).

DOI: 10.1088/1361-651X/ae1bc2

Grain boundary (GB) engineering has been a key topic in addressing the challenges of hydrogen embrittlement in iron. Particularly, the Sigma 3 symmetric tilt GB (STGB) of iron inherits the resistance to hydrogen embrittlement. However, the effect of carbon as a steel solute on the hydrogen embrittlement mechanism remains elusive. Herein, we utilize classical molecular dynamics simulation and density functional theory calculations to investigate the role of carbon atoms on the mechanical properties and the H-atom diffusion mechanism of hydrogenated Sigma 3 (112) 110 STGB Fe. The results reveal a significant decrease in ultimate tensile strength even when only 0.1 wt% of carbon atoms are added. Local lattice structural changes demonstrate a coupling effect between carbon and hydrogen atoms, which accelerates the formation of deformed areas and phase transformation. The addition of a carbon atom is also found to significantly reduce the diffusion barrier, thereby facilitating a hydrogen diffusion.

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