Nonmetallic Inclusion Distribution within Ingots for Power Generation Engineering Forgings

  • N. A. Zyuban
  • D. V. Rutskii
  • S. B. Gamanyuk
  • M. V. Kirilichev
Article
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Results are provided for a study of the distribution and location of nonmetallic inclusions in large forgings of steel 38KhN3MFA weighing 24.2 and 23.52 tons with a normal configuration and with a changed shape of the bottom part (“convex” bottom) cast in a vacuum. It is shown that the change in ingot bottom section geometry leads to an increase in temperature gradient and as a consequence to an increase solid phase advance intensity. In turn, this leads to more uniform distribution of oxysulfide inclusions. The sulfide inclusion content in the ingots compared increases from the periphery to the ingot axis. Dependences are obtained for metal ductility properties, i.e., relative elongation, relative reduction of area, and impact strength on sulfide inclusions distribution over ingot levels, and their unfavorable effect on these properties is established. It is shown that a reason for the reduction in ductility properties is sulfide phase location in the form of films of dendrite boundaries that occurs under conditions of a shortage of oxygen in the melt. This leads to a reduction in oxysulfide content and formation of a sulfide component in an unfavorable form distributed over cast grain boundaries. The ingots are destined for domestic power generation engineering forgings.

Keywords

large ingot solidification nonmetallic inclusions ductility properties oxides sulfides oxysulfides 

References

  1. 1.
    V. V. Tsukanov, Contemporary Steels and Technology in Power Generation Technology, Professional, St. Petersburg (2014).Google Scholar
  2. 2.
    D. Brooksbank and K. W. Andrews, “Stress fields around inclusions and their relation to mechanical properties,” JISI, 210, April, 246–253 (1972).Google Scholar
  3. 3.
    A. V. Dub, N. V. Baraulenkova, T. V. Morozova, et al., “Nonmetallic inclusions in low-alloy pipe steel,” Metallurg, No. 4, 67–77 (2006).Google Scholar
  4. 4.
    M. Sohaciu, C. Predescu, E. Vasile, et al., “Influence of MnS inclusions in steel parts on fatigue resistance,” Digest J. Nanomater. Biostruct., 8, No. 1, 367–376 (2013).Google Scholar
  5. 5.
    R. Kiessling, Non-Metallic Inclusions in Steel, Parts 1–3, London, Publ. 115 (1968); Parts 1–4, London, Metals Society (1978).Google Scholar
  6. 6.
    N. A. Zyuban and O. B. Kryuchkov, “Effect of degassing on features of sulfide inclusion formation and properties of objects of low-alloy structural steels,” Izv. VUZ., Chern. Met., No. 5, 56–60 (2008).Google Scholar
  7. 7.
    O. A. Shevtsova, N. A. Zyuban, S. A. Pegisheva, et al., “Features of sulfide inclusion formation and their location within grains in relation to steel 20 deoxidation conditions,” Metallurg, No. 5, 60–63 (2014).Google Scholar
  8. 8.
    G. A. Pimenov, A. A. Mushilin, V. N. Lebedev, et al., Patent 668753 USSR, IPC В21J5/00, “Forged ingot,” subm. 03.31.1975, publ. 06.25.1979.Google Scholar
  9. 9.
    S. B. Gamanyuk, Study of a Large Forged Steel Ingot of Changed Geometry with the Aim of Improving Forging Metal Quality: Dissert. Cand. Techn. Sci., Volgograd (2012).Google Scholar
  10. 10.
    A. N. Chervyakov and S. A. Kiselev, Metallographic Determination of Inclusions in Steel, Metallurgizdat, Moscow (1962).Google Scholar
  11. 11.
    M. I. Vinograd, Inclusions in Steel and Properties, Metallurgizdat, Moscow (1963).Google Scholar
  12. 12.
    N. Zyuban, D. Rutskii, S. Konovalov, et al., “A study of the development of chemical heterogeneity in large forging ingots: depending upon the confi guration and thermophysical conditions of casting,” Metallurg. Mater. Trans. A. Phys. Metallurgy. Mater. Sci., 45A, No. 13, 6200–6206 (2014).Google Scholar
  13. 13.
    Kh.-I. Shpis, Behavior of Nonmetallic Inclusions in Steel during Crystallization and Deformation [Russian translation], Metallurgiya, Moscow (1971).Google Scholar
  14. 14.
    GOST 1497–84, Metals. Tensile Test Methods, Izd. Standartov, Moscow (1986).Google Scholar
  15. 15.
    GOST 9454–78, Metals. Impact Bending Test Methods at Reduced, Room, and Elevated Temperatures, Izd. Standartov, Moscow (1982).Google Scholar
  16. 16.
    GOST 1778–70, Metallographic Methods for Determining Nonmetallic Inclusions, Gos. Kom. Stand. SM SSSR, Moscow (1970).Google Scholar

Copyright information

© Springer Science+Business Media, LLC, part of Springer Nature 2018

Authors and Affiliations

  • N. A. Zyuban
    • 1
  • D. V. Rutskii
    • 1
  • S. B. Gamanyuk
    • 1
  • M. V. Kirilichev
    • 1
  1. 1.Volgograd State Technical UniversityVolgogradRussia

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