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<p>A double aging strategy is proposed to resolve the strength–toughness dilemma in maraging stainless steels under cryogenic conditions. The process integrates a high-temperature pre-aging to create chemically heterogeneous martensite, followed by low-temperature aging to generate nanoscale Laves precipitates with rapidly reversed austenite. A yield strength of 1642&#xa0;MPa and an impact toughness of 38&#xa0;J at 77&#xa0;K are achieved, preserving near-complete strength while boosting toughness over fourfold versus single-aged counterparts (1648&#xa0;MPa/7.4&#xa0;J). Microstructural analysis demonstrates that Ni heterogeneity from primary aging is responsible for the acceleration of austenite reversion during secondary aging. The final structure combines refined Laves phases (≤ 20&#xa0;nm) and high-density reversed austenite, enabling synergistic strengthening–toughening. A new phase transformation guided paradigm for cryogenic steel design was established.</p>

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Double aging induced chemical heterogeneity overcoming strength–toughness tradeoff in cryogenic steel

  • 期刊论文

  • 发表日期：

    2026年3月13日

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  • Jing-Song Wu,
  • Jing-Wen Zhang,
  • Chen-Xi Liu,
  • Qiu-Zhi Gao,
  • Shu-Ran Chu,
  • Jia-Cheng Yu,
  • Ran Ding

摘要

A double aging strategy is proposed to resolve the strength–toughness dilemma in maraging stainless steels under cryogenic conditions. The process integrates a high-temperature pre-aging to create chemically heterogeneous martensite, followed by low-temperature aging to generate nanoscale Laves precipitates with rapidly reversed austenite. A yield strength of 1642 MPa and an impact toughness of 38 J at 77 K are achieved, preserving near-complete strength while boosting toughness over fourfold versus single-aged counterparts (1648 MPa/7.4 J). Microstructural analysis demonstrates that Ni heterogeneity from primary aging is responsible for the acceleration of austenite reversion during secondary aging. The final structure combines refined Laves phases (≤ 20 nm) and high-density reversed austenite, enabling synergistic strengthening–toughening. A new phase transformation guided paradigm for cryogenic steel design was established.