Hydrogen embrittlement in hard wire steel: mechanisms, influencing factors and future research directions

Hard-wire steel typically exhibits a pearlitic microstructure consisting of alternating ferrite and cementite lamellae. With high strength, wear resistance and fatigue durability, it is widely used in critical applications such as bridge cables, wire ropes and prestressed concrete structures. However, hydrogen embrittlement severely threatens its service safety, particularly in hydrogen-containing or corrosive environments. This review systematically summarizes recent advances in its hydrogen embrittlement behavior, focusing on hydrogen trapping and diffusion characteristics associated with its unique lamellar structure. Key influencing factors, including microstructure and processing conditions, are analyzed. Notably, cold drawing improves both strength and hydrogen embrittlement resistance. This review also identifies critical research gaps, including the lack of direct experimental evidence regarding hydrogen distribution at phase boundaries and insufficient understanding of multi-factor coupling effects under service conditions. Future research directions, such as in situ characterization and interface engineering, are proposed.