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Description:

This study presents a thermomechanical processing strategy to improve the resistance to hydrogen embrittlement (HE) in martensitic steels through controlling variant selection at prior austenite grain boundaries (PAGBs), while retaining ultrahigh tensile strength (>1.5 GPa). Under identical hydrogen-charging conditions, the 10% hot-compressed specimen exhibited the highest HE resistance, correlating with its largest fraction of low-angle PAGB segments. Misorientation-distribution analysis and tensile tests revealed a non-monotonic dependence of compressive strain: an optimal compressive level maximized the beneficial stress-assisted variant selection at PAGBs, whereas excessive strains promoted self-accommodation of transformation strain in the work-hardened austenite, diminishing the beneficial effect. The improved HE resistance stems from reduced hydrogen trapping, enhanced strain-dissipating slip transfer, and increased cohesive energy at PAGBs. Tailoring variant selection at PAGBs through this simple process thus provides an industry-feasible route to hydrogen-resistant high-strength martensitic steels.

Rights:

• Creative Commons BY Attribution 4.0 International
  

Keyword: Martensitic steels, Thermomechanical processing, Variant selection, Hydrogen embrittlement, Intergranular fracture

Date published: 2025-12-30

Publisher: Elsevier BV

Journal:

• Scripta Materialia (ISSN: 13596462) vol. 274 117157

Funding:

• Japan Society for the Promotion of Science JP22K18910, JP23H01717, JP23K13541, and JP24K01221
• Government of Japan Ministry of Education Culture Sports Science and Technology JPMXP1122684766

Manuscript type: Publisher's version (Version of record)

MDR DOI:

First published URL: https://doi.org/10.1016/j.scriptamat.2025.117157

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Updated at: 2026-01-05 10:52:39 +0900

Published on MDR: 2026-01-07 08:24:33 +0900