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<p>Hydrogen storage equipment operating under extreme high-pressure and hydrogen-rich environments faces the challenge of balancing hydrogen embrittlement (HE) resistance with high strength-toughness synergy. Cr–Mo–Ni steel emerges as a promising candidate due to its exceptional cryogenic toughness and mechanical properties. In this study, the mechanisms underlying HE resistance in Cr–Mo–Ni steel were systematically investigated using electron probe microanalysis, transmission electron microscopy, nanoindentation, and hydrogen permeation techniques. This study systematically investigates the HE resistance mechanisms in a Cr–Mo–Ni steel processed via two distinct heat treatment routes: intercritical quenching (QLT at 650&#xa0;°C and 680&#xa0;°C, between A<sub>c1</sub> and A<sub>c3</sub>) and supercritical quenching (QQ′T at 710&#xa0;°C, above A<sub>c3</sub>). The results indicate that the QQ′710T-treated steel exhibits the best overall performance after hydrogen charging, with a yield strength of 694 MPa, tensile strength of 760 MPa, elongation of 13.9 pct, a ductility loss of only 2.5 pct, and a remarkably low HE susceptibility index of 15.2 pct. Microstructural analysis reveals that the QQ′710T process leads to a refined lath martensite structure (205 nm in width), an increased fraction of high-angle grain boundaries (55.3 pct), a reduced segregation band area fraction (19 pct), and the formation of nanoscale Cr-/Mo-rich carbides along with 12.4 vol pct reversed austenite. Analysis of hydrogen-microstructure interactions reveals that hydrogen embrittlement susceptibility is co-determined by multiple microstructural constituents, comprising segregation bands, martensite, high-angle grain boundaries, reversed austenite, and secondary phases, with the segregation bands exhibiting the most pronounced effect. Notably, the presence of 12.4 vol pct reversed austenite leads to a reduction in HE susceptibility while concurrently ensuring excellent cryogenic impact toughness (215 J at –196&#xa0;°C). These findings establish a theoretical foundation for designing heat treatment processes to develop high-strength alloy steels with superior hydrogen embrittlement resistance.</p>

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Effect of Microstructural Regulation on Hydrogen Embrittlement Resistance in Cr–Mo–Ni Steel

  • 期刊论文

  • 发表日期：

    2025年11月5日

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  • L. D. Zhao,
  • X. M. Zang,
  • X. T. Xiao,
  • Q. H. Pang,
  • W. J. Li,
  • M. Xu

摘要

Hydrogen storage equipment operating under extreme high-pressure and hydrogen-rich environments faces the challenge of balancing hydrogen embrittlement (HE) resistance with high strength-toughness synergy. Cr–Mo–Ni steel emerges as a promising candidate due to its exceptional cryogenic toughness and mechanical properties. In this study, the mechanisms underlying HE resistance in Cr–Mo–Ni steel were systematically investigated using electron probe microanalysis, transmission electron microscopy, nanoindentation, and hydrogen permeation techniques. This study systematically investigates the HE resistance mechanisms in a Cr–Mo–Ni steel processed via two distinct heat treatment routes: intercritical quenching (QLT at 650 °C and 680 °C, between Ac1 and Ac3) and supercritical quenching (QQ′T at 710 °C, above Ac3). The results indicate that the QQ′710T-treated steel exhibits the best overall performance after hydrogen charging, with a yield strength of 694 MPa, tensile strength of 760 MPa, elongation of 13.9 pct, a ductility loss of only 2.5 pct, and a remarkably low HE susceptibility index of 15.2 pct. Microstructural analysis reveals that the QQ′710T process leads to a refined lath martensite structure (205 nm in width), an increased fraction of high-angle grain boundaries (55.3 pct), a reduced segregation band area fraction (19 pct), and the formation of nanoscale Cr-/Mo-rich carbides along with 12.4 vol pct reversed austenite. Analysis of hydrogen-microstructure interactions reveals that hydrogen embrittlement susceptibility is co-determined by multiple microstructural constituents, comprising segregation bands, martensite, high-angle grain boundaries, reversed austenite, and secondary phases, with the segregation bands exhibiting the most pronounced effect. Notably, the presence of 12.4 vol pct reversed austenite leads to a reduction in HE susceptibility while concurrently ensuring excellent cryogenic impact toughness (215 J at –196 °C). These findings establish a theoretical foundation for designing heat treatment processes to develop high-strength alloy steels with superior hydrogen embrittlement resistance.