Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Facile route to bulk ultrafine-grain steels for high strength and ductility


Steels with sub-micrometre grain sizes usually possess high toughness and strength, which makes them promising for lightweighting technologies and energy-saving strategies. So far, the industrial fabrication of ultrafine-grained (UFG) alloys, which generally relies on the manipulation of diffusional phase transformation, has been limited to steels with austenite-to-ferrite transformation1,2,3. Moreover, the limited work hardening and uniform elongation of these UFG steels1,4,5 hinder their widespread application. Here we report the facile mass production of UFG structures in a typical Fe–22Mn–0.6C twinning-induced plasticity steel by minor Cu alloying and manipulation of the recrystallization process through the intragranular nanoprecipitation (within 30 seconds) of a coherent disordered Cu-rich phase. The rapid and copious nanoprecipitation not only prevents the growth of the freshly recrystallized sub-micrometre grains but also enhances the thermal stability of the obtained UFG structure through the Zener pinning mechanism6. Moreover, owing to their full coherency and disordered nature, the precipitates exhibit weak interactions with dislocations under loading. This approach enables the preparation of a fully recrystallized UFG structure with a grain size of 800 ± 400 nanometres without the introduction of detrimental lattice defects such as brittle particles and segregated boundaries. Compared with the steel to which no Cu was added, the yield strength of the UFG structure was doubled to around 710 megapascals, with a uniform ductility of 45 per cent and a tensile strength of around 2,000 megapascals. This grain-refinement concept should be extendable to other alloy systems, and the manufacturing processes can be readily applied to existing industrial production lines.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Fig. 1: Mechanical properties.
Fig. 2: Characterization of the microstructure of 4Cu annealed at 760 °C for 5 min.
Fig. 3: Effects of annealing temperature and time on the UFG structure.
Fig. 4: Mechanisms for effective grain refinement and high thermal stability.
Fig. 5: Deformed microstructure of UFG 0Cu and 4Cu.

Data availability

The data that support the findings of this study are available from the corresponding author upon reasonable request. Source data are provided with this paper.


  1. 1.

    Howe, A. Ultrafine grained steels: industrial prospects. Mater. Sci. Technol. 16, 1264–1266 (2000).

    CAS  Google Scholar 

  2. 2.

    Song, R., Ponge, D., Raabe, D., Speer, J. G. & Matlock, D. K. Overview of processing, microstructure and mechanical properties of ultrafine grained bcc steels. Mater. Sci. Eng. A 441, 1–17 (2006).

    Google Scholar 

  3. 3.

    Funakawa, Y., Shiozaki, T., Tomita, K., Yamamoto, T. & Maeda, E. Development of high strength hot-rolled sheet steel consisting of ferrite and nanometer-sized carbides. ISIJ Int. 44, 1945–1951 (2004).

    CAS  Google Scholar 

  4. 4.

    Song, R., Ponge, D. & Raabe, D. Mechanical properties of an ultrafine grained C–Mn steel processed by warm deformation and annealing. Acta Mater. 53, 4881–4892 (2005).

    CAS  ADS  Google Scholar 

  5. 5.

    Ohmori, A., Torizuka, S. & Nagai, K. Strain-hardening due to dispersed cementite for low carbon ultrafine-grained steels. ISIJ Int. 44, 1063–1071 (2004).

    CAS  Google Scholar 

  6. 6.

    Nes, E., Ryum, N. & Hunderi, O. On the Zener drag. Acta Metall. 33, 11–22 (1985).

    CAS  Google Scholar 

  7. 7.

    Chen, Z., Bong, H. J., Li, D. & Wagoner, R. The elastic–plastic transition of metals. Int. J. Plast. 83, 178–201 (2016).

    CAS  Google Scholar 

  8. 8.

    Bouaziz, O., Zurob, H. & Huang, M. Driving force and logic of development of advanced high strength steels for automotive applications. Steel Res. Int. 84, 937–947 (2013).

    CAS  Google Scholar 

  9. 9.

    Grässel, O., Krüger, L., Frommeyer, G. & Meyer, L. W. High strength Fe–Mn–(Al, Si) TRIP/TWIP steels development — properties — application. Int. J. Plast. 16, 1391–1409 (2000).

    MATH  Google Scholar 

  10. 10.

    Zhao, J.-l., Xi, Y., Shi, W. & Li, L. Microstructure and mechanical properties of high manganese TRIP steel. J. Iron Steel Res. Int. 19, 57–62 (2012).

    CAS  Google Scholar 

  11. 11.

    Zhang, M., Li, L., Fu, R. Y., Krizan, D. & De Cooman, B. C. Continuous cooling transformation diagrams and properties of micro-alloyed TRIP steels. Mater. Sci. Eng. A 438–440, 296–299 (2006).

    Google Scholar 

  12. 12.

    Gu, X., Xu, Y., Peng, F., Misra, R. D. K. & Wang, Y. Role of martensite/austenite constituents in novel ultra-high strength TRIP-assisted steels subjected to non-isothermal annealing. Mater. Sci. Eng. A 754, 318–329 (2019).

    CAS  Google Scholar 

  13. 13.

    Huang, J. N. et al. Combining a novel cyclic pre-quenching and two-stage heat treatment in a low-alloyed TRIP-aided steel to significantly enhance mechanical properties through microstructural refinement. Mater. Sci. Eng. A 764, 138231 (2019).

    CAS  Google Scholar 

  14. 14.

    De Moor, E., Speer, J. G., Matlock, D. K., Kwak, J.-H. & Lee, S.-B. Effect of carbon and manganese on the quenching and partitioning response of CMnSi steels. ISIJ Int. 51, 137–144 (2011).

    Google Scholar 

  15. 15.

    Gwon, H., Kim, J.-K., Shin, S., Cho, L. & De Cooman, B. C. The effect of vanadium micro-alloying on the microstructure and the tensile behavior of TWIP steel. Mater. Sci. Eng. A 696, 416–428 (2017).

    CAS  Google Scholar 

  16. 16.

    Tian, Y. et al. A novel ultrafine-grained Fe–22Mn–0.6C TWIP steel with superior strength and ductility. Mater. Charact. 126, 74–80 (2017).

    CAS  Google Scholar 

  17. 17.

    Dini, G., Najafizadeh, A., Ueji, R. & Monir-Vaghefi, S. M. Improved tensile properties of partially recrystallized submicron grained TWIP steel. Mater. Lett. 64, 15–18 (2010).

    CAS  Google Scholar 

  18. 18.

    Kim, Y. W., Kim, J. H., Hong, S.-G. & Lee, C. S. Effects of rolling temperature on the microstructure and mechanical properties of Ti–Mo microalloyed hot-rolled high strength steel. Mater. Sci. Eng. A 605, 244–252 (2014).

    CAS  Google Scholar 

  19. 19.

    Arlazarov, A., Bouaziz, O., Hazotte, A., Gouné, M. & Allain, S. Characterization and modeling of manganese effect on strength and strain hardening of martensitic carbon steels. ISIJ Int. 53, 1076–1080 (2013).

    CAS  Google Scholar 

  20. 20.

    Kim, S.-H., Kim, H. & Kim, N. J. Brittle intermetallic compound makes ultrastrong low-density steel with large ductility. Nature 518, 77–79 (2015).

    CAS  PubMed  ADS  Google Scholar 

  21. 21.

    Chan, H. L., Ruan, H. H., Chen, A. Y. & Lu, J. Optimization of the strain rate to achieve exceptional mechanical properties of 304 stainless steel using high speed ultrasonic surface mechanical attrition treatment. Acta Mater. 58, 5086–5096 (2010).

    CAS  ADS  Google Scholar 

  22. 22.

    Zhou, P., Liang, Z., Liu, R. & Huang, M. Evolution of dislocations and twins in a strong and ductile nanotwinned steel. Acta Mater. 111, 96–107 (2016).

    CAS  ADS  Google Scholar 

  23. 23.

    Sohn, S. S. et al. Ultrastrong medium-entropy single-phase alloys designed via severe lattice distortion. Adv. Mater. 31, 1807142 (2019).

    Google Scholar 

  24. 24.

    Rahman, K. M., Vorontsov, V. A. & Dye, D. The effect of grain size on the twin initiation stress in a TWIP steel. Acta Mater. 89, 247–257 (2015).

    CAS  ADS  Google Scholar 

  25. 25.

    Jiang, S. et al. Ultrastrong steel via minimal lattice misfit and high-density nanoprecipitation. Nature 544, 460–464 (2017).

    CAS  PubMed  ADS  Google Scholar 

  26. 26.

    Blavette, D., Cadel, E., Fraczkiewicz, A. & Menand, A. Three-dimensional atomic-scale imaging of impurity segregation to line defects. Science 286, 2317–2319 (1999).

    CAS  PubMed  Google Scholar 

  27. 27.

    Chookajorn, T., Murdoch, H. A. & Schuh, C. A. Design of stable nanocrystalline alloys. Science 337, 951–954 (2012).

    CAS  PubMed  ADS  Google Scholar 

  28. 28.

    Park, K.-T., Kim, Y.-S., Lee, J. G. & Shin, D. H. Thermal stability and mechanical properties of ultrafine grained low carbon steel. Mater. Sci. Eng. A 293, 165–172 (2000).

    Google Scholar 

  29. 29.

    Stráská, J., Janeček, M., Čížek, J., Stráský, J. & Hadzima, B. Microstructure stability of ultra-fine grained magnesium alloy AZ31 processed by extrusion and equal-channel angular pressing (EX–ECAP). Mater. Charact. 94, 69–79 (2014).

    Google Scholar 

  30. 30.

    Hasegawa, H. et al. Thermal stability of ultrafine-grained aluminum in the presence of Mg and Zr additions. Mater. Sci. Eng. A 265, 188–196 (1999).

    Google Scholar 

  31. 31.

    Fan, D. & Chen, L.-Q. Diffusion-controlled grain growth in two-phase solids. Acta Mater. 45, 3297–3310 (1997).

    CAS  ADS  Google Scholar 

  32. 32.

    Haase, C. et al. On the deformation behavior of κ-carbide-free and κ-carbide-containing high-Mn light-weight steel. Acta Mater. 122, 332–343 (2017).

    CAS  ADS  Google Scholar 

  33. 33.

    Yao, M. J. et al. Strengthening and strain hardening mechanisms in a precipitation-hardened high-Mn lightweight steel. Acta Mater. 140, 258–273 (2017).

    CAS  ADS  Google Scholar 

  34. 34.

    Takeuchi, A. & Inoue, A. Classification of bulk metallic glasses by atomic size difference, heat of mixing and period of constituent elements and its application to characterization of the main alloying element. Mater. Trans. 46, 2817–2829 (2005).

    CAS  Google Scholar 

  35. 35.

    Liang, Z. Y., Li, Y. Z. & Huang, M. X. The respective hardening contributions of dislocations and twins to the flow stress of a twinning-induced plasticity steel. Scr. Mater. 112, 28–31 (2016).

    CAS  Google Scholar 

  36. 36.

    Murr, L. E. Interfacial Phenomena in Metals and Alloys (Addison-Wesley, 1975).

  37. 37.

    De Cooman, B. C., Estrin, Y. & Kim, S. K. Twinning-induced plasticity (TWIP) steels. Acta Mater. 142, 283–362 (2018).

    ADS  Google Scholar 

  38. 38.

    Bai, J. et al. Coherent precipitation of copper in Super 304H austenite steel. Mater. Sci. Eng. A 584, 57–62 (2013).

    CAS  Google Scholar 

  39. 39.

    Humphreys, F. J. & Hatherly, M. Recrystallization and Related Annealing Phenomena 2nd edn (Elsevier, 2004).

  40. 40.

    Gault, B. et al. Advances in the calibration of atom probe tomographic reconstruction. J. Appl. Phys. 105, 034913 (2009).

    ADS  Google Scholar 

  41. 41.

    Moody, M. P., Gault, B., Stephenson, L. T., Haley, D. & Ringer, S. P. Qualification of the tomographic reconstruction in atom probe by advanced spatial distribution map techniques. Ultramicroscopy 109, 815–824 (2009).

    CAS  PubMed  Google Scholar 

  42. 42.

    Blavette, D., Duval, P., Letellier, L. & Guttmann, M. Atomic-scale APFIM and TEM investigation of grain boundary microchemistry in Astroloy nickel base superalloys. Acta Mater. 44, 4995–5005 (1996).

    CAS  ADS  Google Scholar 

  43. 43.

    Ungár, T., Ott, S., Sanders, P. G., Borbély, A. & Weertman, J. R. Dislocations, grain size and planar faults in nanostructured copper determined by high resolution X-ray diffraction and a new procedure of peak profile analysis. Acta Mater. 46, 3693–3699 (1998).

    ADS  Google Scholar 

  44. 44.

    Ungár, T., Dragomir, I., Révész, Á. & Borbély, A. The contrast factors of dislocations in cubic crystals: the dislocation model of strain anisotropy in practice. J. Appl. Crystallogr. 32, 992–1002 (1999).

    Google Scholar 

  45. 45.

    Caul, M., Fiedler, J. & Randle, V. Grain-boundary plane crystallography and energy in austenitic steel. Scr. Mater. 35, 831–836 (1996).

    CAS  Google Scholar 

  46. 46.

    Bouaziz, O., Allain, S. & Scott, C. Effect of grain and twin boundaries on the hardening mechanisms of twinning-induced plasticity steels. Scr. Mater. 58, 484–487 (2008).

    CAS  Google Scholar 

  47. 47.

    Xi, T. et al. Copper precipitation behavior and mechanical properties of Cu-bearing 316L austenitic stainless steel: A comprehensive cross-correlation study. Mater. Sci. Eng. A 675, 243–252 (2016).

    CAS  Google Scholar 

  48. 48.

    Zhang, J.-S. High Temperature Deformation and Fracture of Materials (Elsevier, 2010).

Download references


We thank J. Nutter for technical assistance with precession electron diffraction characterization. J.G. and W.M.R. acknowledge EPSRC project ‘Designing Alloys for Resource Efficiency (DARE)’ (EP/L025213/1) for financial support, and the Henry Royce Institute for Advanced Materials (EP/R00661X/1) for JEOL F200 Transmission Electron Microscope access at Royce @ Sheffield. Z.L. and S.J. acknowledge financial support from the National Natural Science Foundation of China (Nos. 51531001, 51921001, 51671018, 51971018 and 11790293), 111 Project (B07003) and Innovative Research Team in University (IRT_14R05), the Projects of SKL-AMM-USTB (2018Z-01, 2018Z-19 and 2019Z-01), the Fundamental Research Fund for the Central Universities of China (FRF-TP-18-093A1) and National Postdoctoral Program for Innovative Talents (BX20180035). H. Zhang acknowledges support from the US Department of Commerce, NIST under the financial assistance awards 70NANB17H249 and 70NANB19H138. A.V.D. acknowledges support from Materials Genome Initiative funding allocated to NIST. D.G. thanks the UKRI for a Future Leaders Fellowship, MR/T019123/1. Certain commercial equipment, instruments, or materials are identified in this paper to foster understanding. Such identification does not imply recommendation or endorsement by the National Institute of Standards and Technology, nor does it imply that the materials or equipment identified are necessarily the best available for the purpose.

Author information




J.G., S.J., W.M.R. and Z.L. designed the experimental programme. J.G. carried out the main experiments. S.J. and Z.P.L. conducted the 3D-APT, synchrotron experiment and analysed the data. H. Zhang conducted the HR-STEM characterization and analysed the data. J.G. and H. Zhang conducted STEM-EDS mapping and analysed the data. Y.H. analysed XRD patterns for calculation of dislocation density. J.G., S.J., H. Zhang, Z.L. and W.M.R. wrote the manuscript and discussed the results. All authors reviewed and contributed to the final manuscript.

Corresponding authors

Correspondence to Suihe Jiang, Huairuo Zhang, Zhaoping Lu or W. Mark Rainforth.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Peer review information Nature thanks Julie Cairney and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Extended data figures and tables

Extended Data Fig. 1 Mechanical properties.

Engineering stress–strain curves of 0Cu and 4Cu annealed at 760 °C for 5 min and 20 min, and 3Cu annealed at 760 °C for 5 min. Upon the addition of Cu both the yield strength and ultimate tensile strength increase markedly, with ductility comparable to that of 0Cu.

Extended Data Fig. 2 ADF-STEM analysis of 4Cu, 0Cu and 3Cu annealed at 760 °C for 5 min.

a, ADF image (left) of 4Cu showing a high density of nanoprecipiates, and the corresponding SAED pattern (right) showing only the matrix reflection of the [110]fcc zone axis without any extra reflection of the precipitates. b, ADF image of 0Cu showing an average grain size of 2.2 μm. c, ADF image of 3Cu presenting a UFG structure with a high density of nanoprecipitates. No elemental segregation at grain boundaries was detected.

Extended Data Fig. 3 Thermal stability evaluation of UFG structures.

ad, EBSD analysis of 0Cu (a1d1), 3Cu (a2d2) and 4Cu (a3d3) annealed at 760 °C (a), 810 °C (b), 860 °C (c) and 910 °C (d) for 5 min. a4, b4, EBSD maps of 0Cu annealed at 760 °C for 20 min (a4) and 60 min (b4). c4, d4, EBSD maps of 4Cu annealed at 760 °C for 20 min (c4) and 60 min (d4). Owing to their enhanced thermal stability, UFG structures of the Cu-doped alloys can be obtained over a wide range of annealing temperatures and times.

Extended Data Fig. 4 Microstructural analysis of 4Cu annealed at 760 °C for 0.5 min, 1 min and 2 min.

a–c, EBSD analysis of 4Cu annealed at 760 °C for 0.5 min (a), 1 min (b) and 2 min (c), revealing that nucleation for recrystallization occurred extensively after 0.5 min of annealing. As the annealing time extends from 1 min to 2 min, the volume fraction of the recrystallized matrix increases from 76% to 95%. d, e, ABF-STEM image (d) and the reconstruction of the APT dataset (e) of 4Cu annealed for 1 min, showing the formation of equiaxed grains of size 300 ± 150 nm and Cu-rich precipitates with an average size of 3.7 nm and a number density of 8.8 × 1023 m−3. The isoconcentration surfaces are 20 at% Cu.

Extended Data Fig. 5 Effect of the trajectory aberrations of APT on the composition analysis of particles.

The error bars are standard deviations of the mean. The isoconcentration surfaces are 30 at% Cu.

Extended Data Fig. 6 EBSD map of UFG 0Cu and calculation of individual strengthening contribution of dislocations and nanotwins of UFG 0Cu and 4Cu.

a, The EBSD map of UFG 0Cu processed by a two-step cold-rolling and flash-annealing process shows a grain size of 1.1 ± 0.5 μm. b, Twinning gradually dominates the strengthening beyond 15% strain in 4Cu, whereas dislocation multiplication governs the strengthening in the entire deformation stage of the UFG 0Cu.

Extended Data Fig. 7 Deformed microstructure analysis of 4Cu pre-strained to 15% and 45%.

a, b, The corresponding bright-field images of Fig. 5c, d, respectively, showing a high density of dislocations and nanotwins with interspacing of between 300 nm and 500 nm. c, Reconstructed APT data of 4Cu pre-strained to 15% showing some of the nanoprecipitates flattened along the loading direction. d, e, Bright-field TEM image (d) and its corresponding high-resolution misorientation map superimposed with nanotwin boundaries (e) (solid red lines, indexed nanotwin boundaries; thin dashed red lines, nonindexed nanotwin boundaries) obtained using a NanoMEGAS DigiSTAR system with a step size of 1.5 nm. Numerous small dislocation cells (blue arrows) were observed in nanotwins and their interspaces. The isoconcentration surfaces are 20 at% Cu.

Extended Data Fig. 8 Microstructure and mechanical property analyses of TRIP steels and medium entropy alloys with small amounts of Cu.

a, b, EBSD maps of the TRIP steels with composition Fe–15Mn–0.4C (a) and Fe–15Mn–0.4C–3Cu (wt%) (b) after annealing at 730 °C for 5 min. c, Tensile stress–strain curves of the TRIP steels in a, b. d, e, EBSD maps and of 33Co–33Cr–34Ni (d) and (33Co–33Cr–34Ni)0.97Cu0.03 (at%; e) after annealing at 810 °C for 10 min. f, Tensile stress–strain curves of the alloys in d, e. The alloys with minor Cu content exhibit finer microstructures and enhanced mechanical properties.

Extended Data Fig. 9 Modified Williamson–Hall plots of FWHM as a function of \(\,{\boldsymbol{K}}{\bar{{\boldsymbol{C}}}}^{{\boldsymbol{1}}/{\boldsymbol{2}}}\).

a, Analysis of peak broadening for cold-rolled 4Cu alloys. b, Analysis of peak broadening for the pre-strained UFG 0Cu and 4Cu alloys.

Extended Data Table 1 Composition (wt%) of 0Cu, 3Cu and 4Cu alloys

Source data

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Gao, J., Jiang, S., Zhang, H. et al. Facile route to bulk ultrafine-grain steels for high strength and ductility. Nature 590, 262–267 (2021).

Download citation


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing