Atomistic Simulations of Hydrogen Distribution in Fe–C Steels

To engineer low-cost Fe–C based steels for application in hydrogen energy technologies, an understanding of the hydrogen distribution inside the material and how it is affected by the microstructure is vital. Molecular statics and molecular dynamics simulations are used to study hydrogen distribution and transport kinetics in the ferritic and martensitic phases of Fe–C steels, with and without dislocations present. We find that hydrogen preferentially resides in martensite especially in high dislocation density regions near the martensite/ferrite boundaries, in agreement with experiments. Furthermore, the rate of hydrogen transport through ferrite is up to an order of magnitude greater than that in martensite. The fundamental mechanisms behind this phenomenon are analyzed.