Atomistic insights into stress corrosion cracking of ?-Fe in supercritical water: The coupling effect of hydrogen embrittlement and intergranular corrosion

Y Huang and ZX Liu and M Song and ML Zhang and CW Hu and QT Wang and HQ Deng, COMPUTATIONAL MATERIALS SCIENCE, 218, 111991 (2023).

DOI: 10.1016/j.commatsci.2022.111991

Mechanistically understanding stress corrosion cracking (SCC) of Fe- based alloy under extremely hightemperature and high-pressure conditions is a key challenge for designing and optimizing structural materials of the supercritical water (SCW) reactors. The mechanism of SCC of alpha-Fe in supercritical water has been investigated by reactive force-field molecular dynamics simulations, and it is obtained that SCC is caused by the coupling effect of hydrogen embrittlement and intergranular corrosion. Hydrogen atoms in metals induce vacancy formation when the loaded stress is larger than the threshold stress, resulting in forming stable vacancyhydrogen clusters. These stable vacancies pin grain boundary (GB) and act as stress concentrators under sufficient tensile stress, leading to the generation of more vacancies. A large number of vacancies in GB promote intergranular corrosion which directly results in materials failure.

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