Effect of superheat on quality of central equiaxed grain zone of continuously cast bearing steel billet based on two-dimensional segregation ratio

Original Paper


The quality of central equiaxed grain zone (CEGZ) of GCr15 bearing steel billets was investigated at different superheats (20, 25 and 35 °C) by experimental observations and a finite element model in order to optimize superheat in continuous casting process. Several GCr15 billets were collected from the continuous casting shop, and the same CEGZ was chosen for comparison of internal quality of GCr15 billets. Considering the limitation of segregation index at some points, two-dimensional segregation ratio in CEGZ was introduced. Firstly, the segregation ratio and the area of center large dark points in CEGZ obtain the minimum at 25 °C superheat, which indicates that the quality of CEGZ at 25 °C superheat is improved compared with those at 20 and 35 °C superheats for corresponding continuously cast billets. The highest superheat and the lowest superheat are not beneficial for improving the central zone quality in the billets. Secondly, the quality of CEGZ of GCr15 billets increases with a decrease in the secondary dendrite arm spacing of CEGZ. Finally, according to the established finite element model, it is deduced that the secondary dendrite arm spacing of CEGZ is closely related to its later solidification time at solid fraction of 0.5–1.0, and the former will be decreased when decreasing the latter.


Superheat Continuously cast billet Equiaxed grain zone Segregation Solidification time 



The authors are very grateful for National Natural Science Foundation of China (No. 51504047) and Fundamental Research Funds for the Central Universities (No. CDJPY14130001). Meanwhile, the authors acknowledge very valuable discussion with Prof. Guang-hua Wen and Prof. Ping Tang from Chongqing University.


  1. [1]
    Z. Li, J. Lei, H. Xu, F. Yu, H. Dong, W. Cao, J. Iron Steel Res. 28 (2016) 1–12.Google Scholar
  2. [2]
    T. Uesugi, Trans. Iron Steel Inst. Jpn. 26 (1986) 614–620.CrossRefGoogle Scholar
  3. [3]
    M.C. Flemings, ISIJ Int. 40 (2000) 833–841.CrossRefGoogle Scholar
  4. [4]
    G. Engstrom, H. Fredriksson, B. Rogberg, Scand. J. Metall. 12 (1983) 3–12.Google Scholar
  5. [5]
    Y. Xu, E. Wang, Z. Li, A. Deng, J. Iron Steel Res. Int. 24 (2017) 483–489.CrossRefGoogle Scholar
  6. [6]
    S.K. Choudhary, S. Ganguly, ISIJ Int. 47 (2007) 1759–1766.CrossRefGoogle Scholar
  7. [7]
    M. Nakatani, T. Adachi, Y. Sugitani, S. Kobayashi, M. Yoshihara, S. Ishimura, Tetsu-to-Hagané 67 (1981) 1287–1296.CrossRefGoogle Scholar
  8. [8]
    H. Esaka, T. Wakabayashi, K. Shinozuka, M. Tamura, ISIJ Int. 43 (2003) 1415–1420.CrossRefGoogle Scholar
  9. [9]
    Z. Hou, F. Jiang, G. Cheng, ISIJ Int. 52 (2012) 1301–1309.CrossRefGoogle Scholar
  10. [10]
    Y. Tsuchida, M. Nakada, I. Sugawara, S. Miyahara, K. Murakami, S. Tokushige, Trans. Iron Steel Inst. Jpn. 22 (1982) B265–B265.Google Scholar
  11. [11]
    M. Bobadilla, J.M. Jolivet, J.Y.Lamant, M. Larrecq, Mater. Sci. Eng. A 173 (1993) 275–285.CrossRefGoogle Scholar
  12. [12]
    Z. Hou, G. Cheng, F. Jiang, G. Qian, ISIJ Int. 53 (2013) 655–664.CrossRefGoogle Scholar
  13. [13]
    M.C. Flemings, Solidification Processing, McGraw-Hill, New York, 1974.Google Scholar
  14. [14]
    K.P. Young, D.H. Kerkwood, Metall. Mater. Trans. A 6 (1975) 197–205.CrossRefGoogle Scholar
  15. [15]
    S.P. Marsh, M.E. Glicksman, Metall. Mater. Trans. A 27 (1996) 557–567.CrossRefGoogle Scholar
  16. [16]
    S.K. Choudhary, D. Mazumdar, Steel Res. Int. 66 (1995) 199–205.CrossRefGoogle Scholar
  17. [17]
    K. Cai, J. Yang, J. Univ. Sci. Technol. Beijing 11 (1989) 509–514.Google Scholar
  18. [18]
    K.J. Schwerdtfeger, in: Shaping and Treating of Steel, The AISE Steel Foundation, Pittsburgh, PA, 2003, pp. 18.Google Scholar
  19. [19]
    Z. Hou, G. Cheng, C. Wu, C. Chen, Metall. Mater. Trans. B 43 (2012) 1517–1529.CrossRefGoogle Scholar
  20. [20]
    Y. Chang, Z. Hou, W. Wang, Y. Xu, Iron and Steel 51 (2016) No. 11, 43–48, 54.Google Scholar
  21. [21]
    Y. Chen, S. Yang, M. Zhu, Iron and Steel 42 (2007) No. 2, 24–27.Google Scholar
  22. [22]
    T. Sun, F. Yue, H. Wu, C. Guo, Y. Li, Z. Ma, J. Iron Steel Res. Int. 23 (2016) 329–337.CrossRefGoogle Scholar
  23. [23]
    O. Volkova, H.P. Heller, D. Janke, ISIJ Int. 43 (2003)1724–1732.CrossRefGoogle Scholar
  24. [24]
    S. Chakraborty, P. Dutta, Mater. Sci. Technol. 17 (2001) 1531–1538.CrossRefGoogle Scholar
  25. [25]
    W. Kurz, D.J. Fisher, Fundamentals of Solidification, 4th edition, Trans. Tech. Pub., Switzerland, 1998.Google Scholar
  26. [26]
    W. Li, W. Zhu, W. Wang, X. Wang, J. Univ. Sci. Technol. Beijing 25 (2003) 315–318.Google Scholar
  27. [27]
    J. Cui, W. Li, J. Tsinghua Univ. (Sci. Tech.) 41 (2001) No. 8, 5–8.Google Scholar

Copyright information

© China Iron and Steel Research Institute Group 2018

Authors and Affiliations

  • Wei Wang
    • 1
  • Zi-bing Hou
    • 1
  • Yi Chang
    • 1
  • Jiang-hai Cao
    • 1
  1. 1.College of Materials Science and EngineeringChongqing UniversityChongqingChina

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