Hydrogen Behavior in Primary Precipitate of F82H Steel: Atomistic Calculation Based on the Density Functional Theory

Abstract

Formation energy of an isolated hydrogen atom in Cr₂₃C₆ has been investigated using atomisitic calculation based on the density functional theory. The lowest calculated formation energy is −0.48 eV, where a hydrogen atom is located at a trigonal bipyramidal site surrounded by five Cr lattice atoms, due to electric charge of atoms. Although it is a rough estimate, a comparison with the formation energy in Fe may imply that hydrogen retention in F82H steel can be much higher in Cr₂₃C₆-based precipitate than in Fe-based matrix.