Hydrogen embrittlement of a grain boundary in alpha-iron; A Molecular dynamics study

Kadoyoshi, Tomoko; Kaburaki, Hideo; Itakura, Mitsuhiro  ; Yamaguchi, Masatake   

The hydrogen embrittlement of metals in various corrosive environments has been known for over a century, however, its mechanism has not yet been precisely identified. We concentrate on studying the grain boundary embrittlement of alpha-iron in the high hydrogen density region. Molecular dynamics method is mainly employed to study the crack advancement of a simple sigma-3 grain boundary in the presence of hydrogen. A newly developed empirical potential of Fe-H is used. We present the molecular dynamics results of crack advancement in the grain boundary region as a function of hydrogen density under mode I loading condition. The atomistic results are compared with the mesoscopic cohesive zone continuum model based on the first principle results. The results indicate that hydrogen embrittlement of a grain boundary occurs due to the decohesion of a grain boundary in the presence of hydrogen atoms.