Research ArticleMATERIALS SCIENCE

Ultrastrong low-carbon nanosteel produced by heterostructure and interstitial mediated warm rolling

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Science Advances  23 Sep 2020:
Vol. 6, no. 39, eaba8169
DOI: 10.1126/sciadv.aba8169
  • Fig. 1 Scanning electron microscopy micrographs and mechanical properties of typical steel samples.

    (A and B) Engineering stress-strain curves of the cold-rolled and warm-rolled steel samples as compared to the initial fibrous dual-phase (DP) samples. (A1), (A2), and (A3) are the scanning electron microscopy (SEM) micrographs showing the microstructures of the samples with cold rolling reduction of 30, 60, and 90%, respectively. (B1), (B2), and (B3) are the SEM micrographs the SEM micrographs showing the microstructures of the samples with warm rolling reductions of 30, 60, and 90%, respectively. (C) SEM micrograph showing the fibrous DP microstructure.

  • Fig. 2 TEM characterization of the as-rolled microstructures.

    (A) and (B) are bright-field TEM images showing the microstructures in the cold-rolled (CR) and warm-rolled (WR) steel samples, respectively. (C) The grain size distributions in rolled steel samples. (D) A high-resolution TEM image showing details in typical nanolamellae. Panels (E) and (F) are the diffraction patterns attained by fast fourier transformation in the selected areas in marked E and F in (D). (G) A high-resolution TEM image showing a high density of dislocations stored in a nanolamella.

  • Fig. 3 APT analysis for the cold- and warm-rolled samples.

    (A and B) Three-dimensional (3D) atomic maps of C, Si, Mn, and Fe in a 90% warm-rolled sample. (C) Concentrations of C, Si, and Mn atoms measured along the black line drawn in (A). (D) Concentration of C atoms in range of 0 to 100 nm, referenced to (C). (E and F) 3D atomic mappings of C, Si, Mn, and Fe in a cold-rolled sample. (G) Concentration of C, Si, and Mn atoms measured along the black line drawn in (E). (H) Selected profile of C concentration in range of 30 to 130 nm, referenced to (G). wt %, weight %.

  • Fig. 4 In situ TEM observation of the microstructure stability at 300°C.

    (A) to (E) are the TEM images taken at the same location when the sample was maintained at 300°C for 0, 30, 60, 90, and 120 min, respectively. (F) Evolution of thicknesses of the numbered lamellae with respect to annealing time.

  • Fig. 5 Superior mechanical property.

    (A) A highlight of the efficiency of strengthening by warm rolling as compared to the results of other processing methods. (B) A highlight of the contribution of the extreme structural refinement to the strength of carbon steels. The relevant literatures for comparison are listed in table S1. ARB, accumulative roll bonding; DPD, dynamic plastic deformation; ECAP, equal channel angular pressing.

Supplementary Materials

  • Supplementary Materials

    Ultrastrong low-carbon nanosteel produced by heterostructure and interstitial mediated warm rolling

    Bo Gao, Qingquan Lai, Yang Cao, Rong Hu, Lirong Xiao, Zhiyi Pan, Ningning Liang, Yusheng Li, Gang Sha, Manping Liu, Hao Zhou, Xiaolei Wu, Yuntian Zhu

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    • Figs. S1 to S9
    • Table S1

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