Effects of prior austenite grain size on hydrogen embrittlement behavior in high-strength martensitic steel

作者：Xiaodong Lan, Kazuho Okada, I. Gutiérrez‐Urrutia, Akinobu Shibata · 发表于：Materials Science and Engineering A · 年份：2025 · DOI：10.1016/j.msea.2025.149539 · 被引用次数：4 · 研究领域：Hydrogen embrittlement and corrosion behaviors in metals、Microstructure and Mechanical Properties of Steels、Fatigue and fracture mechanics

The present study investigates the effects of prior austenite grain (PAG) size on hydrogen embrittlement behavior in high-strength martensitic steel utilizing slow strain rate tensile tests integrated with digital image correlation (DIC) and X-ray computed tomography analyses. The results demonstrate that PAG refinement significantly improves the hydrogen embrittlement resistance under a similar hydrogen level. DIC analysis reveals that the susceptibility to hydrogen embrittlement originates from the plastic deformation related to the lath martensite microstructure. PAG refinement mitigates the microstructure-related strain localization, thereby enhancing the hydrogen embrittlement resistance. Additionally, PAG refinement increases the apparent fracture toughness by promoting greater plastic work and enhancing crack meandering/branching, though the latter effect peaks at a medium PAG size. The enhanced resistance to hydrogen embrittlement thus could be attributed to several factors: reduced strain localization, lower local hydrogen concentration per unit area of PAG boundaries, frequent deflection of intergranular cracks, and an increased density of high-angle boundaries that impede quasi-cleavage cracks—all facilitated by PAG refinement.