Anisotropic lattice distortion makes ultrastrong martensitic steel ductile

Nature Materials (2026)Cite this article Making ultrahigh-strength as-quenched carbon martensitic steels ductile remains a critical challenge for structural applications. The ordered occupancy of carbon at interstitial sites in body-centred cubic martensite induces anisotropic lattice distortion, forming brittle body-centred tetragonal martensite with suppressed dislocation activity. Conventional tempering eliminates this distortion to improve ductility. Here we propose a counterintuitive strategy to unlock the ductility of a 2.4-GPa as-quenched carbon martensitic steel by utilizing the anisotropic lattice distortion of martensite. Its severe lattice distortion, that is, its high tetragonality, is driven by large-concentration substitutional solutes and carbon. The deliberately introduced high tetragonality activates deformation twins as a plastic carrier, effectively overcoming the brittleness of quenched carbon martensitic steel. This strategy of using solid-solution-induced anisotropic lattice distortion challenges the conventional view of tetragonal martensite’s inherent brittleness, establishing a framework for alloy design that yields strong and ductile metallic materials.This is a preview of subscription content, access via your institution Access Nature and 54 other Nature Portfolio journals Get Nature+, our best-value online-access subscription $32.99 / 30 days cancel any timeSubscribe to this journal Receive 12 print issues and online access $259.00 per yearonly $21.58 per issueBuy this articleUSD 39.95Prices may be subject to local taxes which are calculated during checkoutSource data are provided with this paper. Other data generated or analysed during this study are included in the Supplementary Information.Ritchie, R. O. The conflicts between strength and toughness. Nat. Mater. 10, 817–822 (2011).Article CAS PubMed Google Scholar Wei, Y. et al. Evading the strength–ductility trade-off dilemma in steel through gradient hierarchical nanotwins. Nat. Commun. 5, 3580 (2014).Article PubMed PubMed Central Google Scholar He, B. B. et al. High dislocation density-induced large ductility in deformed and partitioned steels. Science 357, 1029–1032 (2017).Article CAS PubMed Google Scholar Wang, L. et al. Tailoring planar slip to achieve pure metal-like ductility in body-centred-cubic multi-principal element alloys. Nat. Mater. 22, 950–957 (2023).Article CAS PubMed Google Scholar Wang, Y., Chen, M., Zhou, F. & Ma, E. High tensile ductility in a nanostructured metal. Nature 419, 912–915 (2002).Article CAS PubMed Google Scholar Wu, X., Jiang, P., Chen, L., Yuan, F. & Zhu, Y. T. Extraordinary strain hardening by gradient structure. Proc. Natl Acad. Sci. USA 111, 7197–7201 (2014).Article CAS PubMed PubMed Central Google Scholar Lu, L., Shen, Y., Chen, X., Qian, L. & Lu, K. Ultrahigh strength and high electrical conductivity in copper. Science 304, 422–426 (2004).Article CAS PubMed Google Scholar Lu, K., Lu, L. & Suresh, S. Strengthening materials by engineering coherent internal boundaries at the nanoscale. Science 324, 349–352 (2009).Article CAS PubMed Google Scholar Pan, Q. et al. Gradient cell-structured high-entropy alloy with exceptional strength and ductility. Science 374, 984–989 (2021).Article CAS PubMed Google Scholar Fang, T. H., Li, W. L., Tao, N. R. & Lu, K. Revealing extraordinary intrinsic tensile plasticity in gradient nano-grained copper. Science 331, 1587–1590 (2011).Article CAS PubMed Google Scholar Cheng, Z., Zhou, H., Lu, Q., Gao, H. & Lu, L. Extra strengthening and work hardening in gradient nanotwinned metals. Science 362, eaau1925 (2018).Article PubMed Google Scholar Valiev, R. Nanostructuring of metals by severe plastic deformation for advanced properties. Nat. Mater. 3, 511–516 (2004).Article CAS PubMed Google Scholar Morito, S., Nishikawa, J. & Maki, T. Dislocation density within lath martensite in Fe–C and Fe–Ni alloys. ISIJ Int. 43, 1475–1477 (2003).Article CAS Google Scholar Nishiyama, Z. Martensitic Transformation (Elsevier, 2012).Krauss, G. Martensite in steel: strength and structure. Mater. Sci. Eng. A 273–275, 40–57 (1999).Article Google Scholar Zener, C. Kinetics of the decomposition of austenite. Trans. AIME 167, 550–595 (1946).

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Characteristic features of shape memory effect and related transformation behavior in Fe-based alloys. Mater. Sci. Eng. A 273–275, 67–88 (1999).Article Google Scholar Download referencesWe thank K. Lu for his insightful discussions on this paper and the technical support from SUSTech Core Research Facilities. We thank Y. X. Liu, Y. Wang and C. Hu for technical support. Funding: M.X.H. acknowledges the support from the National Natural Science Foundation of China (nos. 52425105 and 52130102), the National Key Research and Development Program of China (no. 2019YFA0209900), the Research Grants Council of Hong Kong (no. 17307123, C7045-19E) and the New Cornerstone Science Foundation through the XPLORER PRIZE. B.B.H. is grateful for the financial support from the National Natural Science Foundation of China (grant no. 52471135), the Guangdong Basic and Applied Basic Research Foundation (no. 2024B1515120036), the Science and Technology Innovation Commission of Shenzhen (project no. JCYJ20210324120209026; KQTD2019092917250571), the Open Research Fund of Songshan Lake Materials Laboratory (2023SLABFK02), the Major Talent Programs of Guangdong Province (contract no. 2019QN01C435) and the High Level of Special Funds from SUSTech (G03034K003). We also acknowledge the Shanghai Synchrotron Radiation Facility for providing the synchrotron XRD facility at the BL02U2 beamline.Center for Structural Materials, Department of Mechanical Engineering, University of Hong Kong, Hong Kong, ChinaS. Pan & M. X. HuangDepartment of Mechanical and Energy Engineering, Southern University of Science and Technology, Shenzhen, ChinaS. Pan & B. B. HeSearch author on:PubMed Google ScholarSearch author on:PubMed Google ScholarSearch author on:PubMed Google ScholarM.X.H. and B.B.H. supervised and designed the study. S.P. carried out the experimental work. All authors analysed the data. S.P. drafted the manuscript. All authors reviewed and edited the manuscript.Correspondence to B. B. He or M. X. Huang.The authors declare no competing interests.Nature Materials thanks William Rainforth and Marcel Somers for their contribution to the peer review of this work. Peer reviewer reports are available.Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.Supplementary Notes 1–4, Figs. 1–17, Tables 1 and 2 and refs. 1–9.Statistical source data.Statistical source data.Statistical source data.Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.Reprints and permissionsPan, S., He, B.B. & Huang, M.X. Anisotropic lattice distortion makes ultrastrong martensitic steel ductile. Nat. Mater. (2026). https://doi.org/10.1038/s41563-026-02588-5Download citationReceived: 22 August 2025Accepted: 24 March 2026Published: 16 April 2026Version of record: 16 April 2026DOI: https://doi.org/10.1038/s41563-026-02588-5Anyone you share the following link with will be able to read this content:Sorry, a shareable link is not currently available for this article. Provided by the Springer Nature SharedIt content-sharing initiative