Crack tip hydrogen diffusion with multiple type traps and implications for hydrogen assisted cracking

Hydrogen effects on fracture are ruled by its amounts in microstructural features that entrap the species and are actual sites of the embrittlement events. The paper aims to describe hydrogen delivery to diverse concurring microstructural positions basing on comprehensive diffusion trapping theory that relies on minimal a priori constraints. The operation of multiple type traps near a crack in a model steel system that uptakes hydrogen during loading is elucidated. The calculations validate the postulate of local lattice-trap equilibrium and the dominance of hydrogen transport by only lattice-site diffuser flow. The simulations exhaustively describe the functioning of multifarious microstructural features and reveal their potentiality both to carry out the mechanistic effects of hydrogen and to retard hydrogen accumulation in the fracture nuclei.