Effect of Titanium Levels on the Hot Tearing Sensitivity and Abnormal Grain Growth After T4 Heat Treatment of Al–Zn–Mg–Cu Alloys

  • Xiaochun Zeng
  • Cassandra Ferguson
  • Kumar Sadayappan
  • Sumanth Shankar
Article
  • 23 Downloads

Abstract

In this paper, the castability of Al–6wt%Zn–2wt%Mg–2wt%Cu alloy with different titanium levels was investigated with a constrained rod casting (CRC) mold. With the increasing level of titanium, the hot tearing sensitivity (HTS) index decreased from the value of 17 (without Ti) to the value of 7 (0.06 wt% of Ti). But further increasing of titanium weight percentage will deteriorate the castability of the alloys. The HTS index increased from the value of 7 (0.06 wt% of Ti) to the value of 13 (0.24 wt% of Ti). The grain sizes and grain morphologies of as-cast as well as solid solution-treated samples with different Ti levels were measured and analyzed. For the CRC mold castings, the grain size decreased with the increasing of Ti levels in the as-cast samples, and the grain morphology was changed from dendrite to globular. The Ti level required for minimum grain size decreased as the cooling rate of solidification increased. After solid solution treatment, abnormal grain growth occurred only in samples with less than 0.1 wt% of Ti. The tensile samples with different Ti levels were cast in the tilt pouring cast machine with permanent mold. The tensile test results of heat-treated samples show that the samples with grain growth during heat treatment did not affect the tensile properties.

Keywords

castability hot tearing HTS Al–Zn–Mg–Cu alloy AA7050 grain refinement abnormal grain coarsening Al–5Ti–1B 

Notes

Acknowledgements

The authors wish to thank the Natural Science and Engineering Research Council of Canada for the funding of this project.

References

  1. 1.
    Office of Transportation and Air Quality, EPA and NHTSA set standards to reduce greenhouse gases and improve fuel economy for model years 2017–2025 cars and light trucks, https://nepis.epa.gov/Exe/ZyPDF.cgi/P100EZ7C.PDF?Dockey=P100EZ7C.PDF. Accessed 27 Sept 2017
  2. 2.
    North American Light Vehicle Aluminum Content Study: Executive Summary, Duker Worldwide, 2014, http://www.autonews.com/assets/PDF/CA95065611.PDF. Accessed 27 Sept 2017
  3. 3.
    R. Ghiaasiaan, PhD Dissertation, McMaster University, Hamilton, ON, 2015Google Scholar
  4. 4.
    J.A. Spittle, S.G.R. Brown, Mater. Sci. Tech. 21(9), 1071–1077 (2005)CrossRefGoogle Scholar
  5. 5.
    S. Lin, PhD Thesis, University of Quebec at Chicoutimi, Chicoutimi, Quebec, 1999Google Scholar
  6. 6.
    J. Cambell, Castings (Butterworth-Heineman Ltd., Oxford, 1991), pp. 209–232Google Scholar
  7. 7.
    S. Vernede, J.A. Dantzing, M. Rappaz, Acta Mater. 57, 1554–1569 (2009)CrossRefGoogle Scholar
  8. 8.
    W.S. Pellini, Foundry 80, 125–199 (1952)Google Scholar
  9. 9.
    S. Li, D. Apelian, Int. J. Metalcast 5, 23–40 (2011)CrossRefGoogle Scholar
  10. 10.
    D. Warrington, D.G. McCartney, Cast Metal 3(4), 202–208 (1991)CrossRefGoogle Scholar
  11. 11.
    M. Easton, D. StJohn, L. Sweet, Mater. Sci. Forum 630, 213–221 (2009)CrossRefGoogle Scholar
  12. 12.
    T.E. Quested, A.L. Greer, Acta Mater. 52, 3859–3868 (2004)CrossRefGoogle Scholar
  13. 13.
    A.L. Greer, Phil. Trans. R. Soc. Lond. A 361, 479–495 (2003)CrossRefGoogle Scholar
  14. 14.
    T.E. Quested, A.L. Greer, Acta Materialia 53(9), 2683–2692 (2005)CrossRefGoogle Scholar
  15. 15.
    W. Kurz, D. Fisher, Fundamentals of Solidification, 4th edn. (Trans Tech Publications, Aedermannsdorf, 1989)Google Scholar
  16. 16.
    M.E. Glicksman, Principles of Solidification (Springer, New York, 2011)CrossRefGoogle Scholar
  17. 17.
    D.M. Stefanescu, Science and Engineering of Casting Solidification, 2nd edn. (Springer, New York, 2009)Google Scholar
  18. 18.
    J. Kramp, MASc thesis, McMaster University, 2018Google Scholar
  19. 19.
    Y. Li et al., Metall. Mater. Trans. A (2016).  https://doi.org/10.1007/s11661-016-3543-2 Google Scholar
  20. 20.
    G. Cao, S. Kou, Metall. Mater. Trans. A 37A, 3647–3663 (2006)CrossRefGoogle Scholar
  21. 21.
    G. Cao, C. Zhang, H. Cao, Y.A. Chang, S. Kou, Metall. Mater. Trans. A 41A, 706–716 (2010)CrossRefGoogle Scholar
  22. 22.
    G. Birsan, P. Ashtari, S. Shankar, Int. J. Cast Metal Res. 24(6), 378–384 (2011)CrossRefGoogle Scholar
  23. 23.
    P. Schumacher, in Solidification and Casting, ed. by B. Cantor, K. O’Reilly (IOP Publishing Ltd, Bristol, 2003), pp. 177–198Google Scholar
  24. 24.
    L. Greer, in Solidification and Casting, ed. by B. Cantor, K. O’Reilly (IOP Publishing Ltd, Bristol, 2003), pp. 199–247Google Scholar
  25. 25.
    A. Mazahery, MASc thesis, McMaster University, 2016Google Scholar
  26. 26.
    C.S. Smith, Met. Soc. Trans. AIME 175, 345 (1948)Google Scholar
  27. 27.
    T. Gladman, Proc. R. Soc. 294A, 298 (1966)CrossRefGoogle Scholar
  28. 28.
    M. Hillert, in International Conference on Physical Metallurgy of Thermomechanical Processing Thermec-88 Tokyo, Japan, ed by I. Tamusa (Iron and Steel Institute, Japan, 1988), pp. 30Google Scholar
  29. 29.
    A. Waheed, G.W. Lorimer, J. Mater. Sci. Lett. 16, 1643–1646 (1997)CrossRefGoogle Scholar
  30. 30.
    K.T. Kashyap, Bull. Mater. Sci. 24(6), 643–648 (2001)CrossRefGoogle Scholar

Copyright information

© American Foundry Society 2018

Authors and Affiliations

  1. 1.Light Metal Casting Research CenterMcMaster UniversityHamiltonCanada
  2. 2.Canmet Materials, Natural Resources CanadaHamiltonCanada

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