Effect of hydrogen on the interaction between dislocation and Cr precipitate in BCC Fe
Fe-Cr-based ferritic/martensitic(FM)steels,used as structural materials for the fourth generation nuclear reactors,are subjected to premature failure due to the generation of large amounts of hydrogen atoms caused by transmutation reactions in the service environment.In this paper,the effect of hydrogen on the inter-action between the edge dislocations and Cr precipitates in BCC Fe was investigated based on molecular dy-namics using the recently developed angle-dependent potential(ADP)of the Fe-Cr-H ternary system.The re-sults show that hydrogen atoms reduce the critical depinning stress required for dislocation to detach from the Cr precipitate.Under lower strain rates(5×107 s-1,2×107 s-1),hydrogen reduces the critical debonding stress significantly,while under higher strain rates(108 s-1),the hydrogen-induced change of the critical stress is not significant.The smaller is the distance between precipitates,the larger is the critical depinning stress of hydrogen reduction,and vice versa.
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