Influence of nanocarbides on stress corrosion cracking of high-strength steels: hydrogen embrittlement-dominated mechanism

Stress corrosion cracking (SCC) in high-strength steels mainly results from the combined effects of hydrogen embrittlement (HE) and anodic dissolution (AD). This review evaluates how nanoscale carbides, such as NbC, TiC, and (Nb,Mo)C, modulate these competing degradation mechanisms, with an emphasis on their preferential mitigation of HE. These carbides form hierarchical hydrogen trap networks, including carbon vacancies, semi-coherent interfaces, and dislocation sites, which effectively suppress hydrogen diffusion and accumulation at crack tips. In contrast, their influence on AD is limited due to low electrochemical activity and weak galvanic interaction with steel matrix. This reflects a selective regulatory behavior: Nanocarbides markedly mitigate hydrogen-assisted cracking while exerting negligible effects on AD. Overall, this review demonstrates that nanoscale carbides regulate SCC in a selective manner: They strongly mitigate HE through efficient trapping, while exerting minimal influence on anodic dissolution. Additionally, this review outlines the microstructural design strategies and recent advances in multiscale modeling approaches. These insights support the design of hydrogen-tolerant steels with improved SCC resistance.