Hydrogen embrittlement (HE) is a key challenge limiting the utilization of ultra-high strength martensitic steel. In this work, we reported a novel method for dramatically improving HE resistance by Ta microalloying, and the significant effect of Ta on the HE susceptibility of lath martensitic steel was elucidated from the perspectives of hydrogen-enhanced decohesion (HEDE) and hydrogen-enhanced localized plasticity (HELP). As the Ta content increased, numerous dispersed nano-sized TaC precipitates were generated and the effective areas of martensite/prior austenite grain boundaries also increased, which increased both the irreversible/reversible H trap densities, impeded localized H aggregation at defects and weakened HEDE. A quantitative analysis regarding each type of H trap revealed that, compared with reversible traps provided by microstructural refinement, TaC precipitate-induced irreversible traps exhibited a dominant role in weakening the HEDE process. Additionally, in Ta-bearing steels, the resistance to hydrogen-assisted crack propagation was enhanced through the increased Σ11 boundary, increased low-angle grain boundary fraction and the reduced Σ3 boundary fraction, which combined with the suppressing role of TaC precipitates on H-dislocation interaction, impeded the HELP process. This study provided new, deep insights into the impact of Ta on HE, which has important implications for developing steels with high HE resistance.

氢脆（HE）是限制超高强度马氏体钢应用的关键挑战。在这项工作中，我们报道了一种通过 Ta 微合金化显着提高 HE 抗性的新方法，并从氢增强脱聚 (HEDE) 和氢增强局域化的角度阐明了 Ta 对板条马氏体钢 HE 敏感性的显着影响。可塑性（帮助）。随着Ta含量的增加，产生大量分散的纳米级TaC析出物，马氏体/原奥氏体晶界的有效面积也增加，这增加了不可逆/可逆H陷阱密度，阻碍了H在缺陷处的局部聚集并削弱了HEDE。对每种类型的 H 陷阱的定量分析表明，与微观结构细化提供的可逆陷阱相比，TaC 沉淀诱导的不可逆陷阱在削弱 HEDE 过程方面表现出主导作用。此外，在含Ta钢中，通过增加Σ11晶界、增加小角晶界分数和减少Σ3晶界分数，结合TaC析出物对H-的抑制作用，增强了抗氢辅助裂纹扩展的能力。位错相互作用，阻碍了 HELP 过程。这项研究为 Ta 对 HE 的影响提供了新的、深入的见解，这对开发具有高 HE 抗性的钢具有重要意义。通过增加 Σ11 晶界、增加小角度晶界分数和减少 Σ3 晶界分数来增强对氢辅助裂纹扩展的抵抗力，再加上 TaC 析出物对 H-位错相互作用的抑制作用，阻碍了 HELP 过程。这项研究为 Ta 对 HE 的影响提供了新的、深入的见解，这对开发具有高 HE 抗性的钢具有重要意义。通过增加 Σ11 晶界、增加小角度晶界分数和减少 Σ3 晶界分数来增强对氢辅助裂纹扩展的抵抗力，再加上 TaC 析出物对 H-位错相互作用的抑制作用，阻碍了 HELP 过程。这项研究为 Ta 对 HE 的影响提供了新的、深入的见解，这对开发具有高 HE 抗性的钢具有重要意义。