Modeling of the mechanism of delayed fracture initiation

Kaburaki, Hideo; Yamaguchi, Masatake   ; Ebihara, Kenichi   ; Itakura, Mitsuhiro  ; Kadoyoshi, Tomoko; Suzudo, Tomoaki   

Hydrogen greatly changes mechanical properties of metals, and, in particular, causes delayed fracture of high strength steels. Hydrogen-induced embrittlement has been known for almost a century, and, yet its mechanism is not exactly identified. We concentrated on studying the intergranular brittle fracture at high hydrogen content, using numerical methods, such as first principles calculation, cohesive zone model, and continuum model. We show from the simulation results that a hydrogen-induced intergranular fracture occurs due to the weakening of atomic bonds at the grain boundary region.