Advertisement

Metals and Materials

, Volume 5, Issue 6, pp 571–578 | Cite as

Effect of controlled cooling on the formability of TS 590 MPa grade hot-rolled high strength steels

  • Yeol-Rae Cho
  • Jin-Hwan Chung
  • Hwang-Hoe Ku
  • In-Bae Kim
Article

Abstract

The effect of cooling on the mechanical properties of hot-rolled high strength steels was investigated in order to improve the stretch-flangeability of conventional TS 590 MPa grade for the automotive parts through laboratory simulation and mill-scale production. The low temperature coiling method using a 3-step controlled cooling pattern after hot rolling was very effective for producing Nb-bearing high strength steel with high stretch- flangeability. It was suggested that the suppressed precipitation of grain boundary cementites and the decreased hardness difference between the ferrite matrix and bainite phases cause the excellent stretch-flangeability of ferrite-bainite duplex microstructure steel. Therefore, the formation and propagation of microcracks were suppressed relative to conventional HSLA steel with the ferrite and pearlite microstructure. In addition, the elongation improved compared with that of hot-rolled steel sheets using the conventional early cooling pattern because the volume fraction of polygonal ferrite increased.

Key words

ferrite-bainite duplex microstructure stretch-flangeability controlled cooling Nb added hot-rolled high strength steels automotive wheel discs 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. 1.
    S. Hashimoto, M. Sudo, K. Mimura and T. Hosoda,Trans. ISIJ 26, 985 (1986).Google Scholar
  2. 2.
    H. Kimura, M. Kinoshita, T. Okita and M. Mori,CAMP-ISIJ 5, 1855 (1992).Google Scholar
  3. 3.
    O. Kawano, J. Wakita and M. Takahashi,Tetsu-to-Hagane 82, 73 (1996).Google Scholar
  4. 4.
    O. Kawano, J. Wakita, K. Esaka and H. Abe,CAMP-ISIJ 8, 568 (1995).Google Scholar
  5. 5.
    N. Imai, N. Komatsubara and K. Kunishige,CAMP-ISIJ 8, 572 (1995).Google Scholar
  6. 6.
    I. Tsukatani, S. Hashimoto and T. Inoue,ISIJ Int. 31, 992 (1991).CrossRefGoogle Scholar
  7. 7.
    H. Kimura, M. Hori, M. Kinoshita, T. Okita,CAMP-ISIJ 4, 784 (1991).Google Scholar
  8. 8.
    O. Kawano, J. Wakita, K. Esaka and H. Abe,CAMP-ISIJ 1, 877 (1988).Google Scholar
  9. 9.
    O. Kawano, J. Haji, J. Wakita, K. Esaka and H. Abe,CAMP-ISIJ 3, 797 (1990).Google Scholar
  10. 10.
    H. Ide, O. Kawano, H. Abe, N. Ikenaga, J. Wakita and K. Esaka,CAMP-ISIJ 4, 783 (1991).Google Scholar
  11. 11.
    J. Mano, M. Nishida, T. Tanaka, T. Kato, N. Aoyagi and N. Yamada,Tetsu-to-Hagane 68, 1298 (1982).Google Scholar
  12. 12.
    K. Kunishige, M. Takahashi, S. Sugisawa and Y. Masui,Tetsu-to-Hagane 65, 1916 (1979).Google Scholar
  13. 13.
    S. Sugisawa, S. Hamamatsu, K. Kikuchi and K. Kunishige,Tetsu-to-Hagane 68, 1256 (1982).Google Scholar
  14. 14.
    T. Sakagami, T. Higashino, N. Aoyagi, M. Morita, N. Kurosawa and T. Kato,CAMP-ISIJ 6, 1695 (1993).Google Scholar
  15. 15.
    T. Sakagami, T. Higashino, M. Morita and N. Kurosawa,CAMP-ISIJ 8, 1687(1995).Google Scholar
  16. 16.
    K. Mimura, M. Miyahara and Z. Shibata,CAMP-ISIJ 5, 1859(1992).Google Scholar
  17. 17.
    S. Hashimoto, K. Mimura, T. Hosoda and M. Sudo,Tetsu-to-Hagane 72, 1786 (1986).Google Scholar
  18. 18.
    M. Kinoshita, H. Kimura, K. Osawa, T. Okita, H. Owada and M. Hori,NKK Technical Reports 145, 1 (1994).Google Scholar
  19. 19.
    S. Nomura, N. Komatsubara, K. Kunishige and H. Fuku-yama,CAMP-ISIJ 5, 1851 (1992).Google Scholar
  20. 20.
    N. Imai, N. Komatsubara, K. Kunishige and S. Nomura,CAMP-ISIJ 9, 1092(1996).Google Scholar
  21. 21.
    M. Sudo, S. Hashimoto and S. Kambe,Trans. ISIJ 23, 303 (1983).Google Scholar
  22. 22.
    Y.R. Cho and J.H. Chung,Proc. of the 10th conf. on Mechanical Behaviors of Materials, p. 153, The Korean Inst. of Met. & Mater., Korea (1996).Google Scholar

Copyright information

© Springer 1999

Authors and Affiliations

  • Yeol-Rae Cho
    • 1
  • Jin-Hwan Chung
    • 1
  • Hwang-Hoe Ku
    • 1
    • 2
  • In-Bae Kim
    • 1
    • 3
  1. 1.Technical Research LaboratoriesPohang Iron & Steel Co., Ltd.Kwangyang545-090Korea
  2. 2.Kwangyang Steel WorksPohang Iron & Steel Co., Ltd.KwangyangKorea
  3. 3.Department of Metallurgical EngineeringPusan National UniversityPusanKorea

Personalised recommendations