Metallurgical and Materials Transactions A

, Volume 38, Issue 10, pp 2419–2427 | Cite as

Effects of Copper and Malleablizing Time on Mechanical Properties of Austempered Malleable Iron

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Abstract

In this study, both the unalloyed and 1 wt pct copper alloyed white irons were successively treated with a duplex heating process consisting of malleablizing and austempering, and then the effects of copper and processing variables on microstructure and mechanical properties of the austempered malleable iron (AMI) were investigated. The results showed that AMI could effectively shorten malleablizing time to obtain the constituents of irregular graphite, acicular ferrite, and retained austenite in the microstructure. Moreover, 1 pct Cu-AMI had a higher retained austenite content than unalloyed AMI. This is because copper is an austenite stabilizer and acts to delay the start of the transformation into ausferrite. In the case of mechanical properties, AMI increased tensile strength (1083 to 1190 MPa) and impact toughness (16 to 22 J) by 2 to 3 times after 930 °C–20 hours malleablizing treatment as compared to as-cast (572 to 580 MPa and 5 to 6 J). In particular, 1 pct Cu-AMI had better performance than unalloyed AMI except for hardness. In comparison with conventional malleable irons, AMI was found to possess better tensile and impact properties.

Keywords

Austenite Impact Toughness Ductile Iron Acicular Ferrite Austempering 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.
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Notes

Acknowledgments

The authors express their sincere thanks for the financial support of the National Science Council (Taiwan, ROC) under Contract No. NSC90-2216-E-036-030.

References

  1. 1.
    V.B. John: Introduction to Engineering Materials, Macmillan, London, 1992, pp. 243–45Google Scholar
  2. 2.
    R.A. Film, P.K. Trojan: Engineering Materials and Their Applications, Houghton Mifflin, Boston, MA, 1990, pp. 435–39Google Scholar
  3. 3.
    R. Elliott: Cast Iron Technology, Butterworth and Co., London, 1988, pp. 33–36Google Scholar
  4. 4.
    W.F. Smith: Structure and Properties of Engineering Alloys, McGraw-Hill Inc., New York, NY, 1993, pp. 365–68Google Scholar
  5. 5.
    L.R. Jenkins: Heat Treating of Malleable Irons, ASM Handbook, ASM INTERNATIONAL, Materials Park, OH, 1991, vol. 4, pp. 693–96Google Scholar
  6. 6.
    C.F. Walton: Iron Castings Handbook, Iron Castings Society, Inc., Cleveland, OH, 1981, pp. 297–322Google Scholar
  7. 7.
    J.R. Laub: Adv. Mater. Processes, 1994, vol. 2, pp. 40–43Google Scholar
  8. 8.
    Y.S. Lerner, G.R. Kingsbury: JMEPEG, 1998, vol. 7(1), pp. 48–52CrossRefGoogle Scholar
  9. 9.
    C.H. Hsu, S.C. Lee, H.P. Feng, Y.H. Shy: Metall. Mater. Trans. A, 2001, vol. 32A, pp. 295–303CrossRefGoogle Scholar
  10. 10.
    C.H. Hsu, T.L. Chuang: Metall. Mater. Trans. A, 2001, vol. 32A, pp. 2509–13CrossRefGoogle Scholar
  11. 11.
    C.H. Hsu, S.C. Lee: Mater. Sci. Technol., 1995, vol. 11, pp. 765–75Google Scholar
  12. 12.
    C.H. Hsu, Y.H. Shy, S.C. Lee: Mater. Chem. Phys., 2000, vol. 63, pp. 75–81CrossRefGoogle Scholar
  13. 13.
    Y. Tanaka, H. Kage: Mater. Trans., JIM, 1992, vol. 33(6), pp. 543–57Google Scholar
  14. 14.
    A.S. Hamid, R. Elliott: Mater. Sci. Technol., 1996, vol.12, pp. 679–90Google Scholar
  15. 15.
    ASTM E8M, Annual Book of ASTM Standards, ASTM, Philadelphia, PA, 1997, vol. 03.01, pp. 77–97Google Scholar
  16. 16.
    ASTM E327M, Annual Book of ASTM Standards, ASTM, Philadelphia, PA, 1997, vol. 01.02, pp. 151–53Google Scholar
  17. 17.
    B.D. Cullity: Elements of X-ray Diffraction, Addison-Wesley, London, 1978, pp. 411–15Google Scholar
  18. 18.
    ASTM E975, Annual Book of ASTM Standards, ASTM, Philadelphia, PA, 1997, vol. 03.01, pp. 684–89Google Scholar
  19. 19.
    W.F. Smith: Structure and Properties of Engineering Alloys, McGraw-Hill, London, 1993, pp. 336–39Google Scholar
  20. 20.
    I. Minkoff: The Physical Metallurgy of Cast Iron, John Wiley & Sons, New York, NY, 1983, pp. 81–85Google Scholar
  21. 21.
    ASTM A644, Annual Book of ASTM Standard, ASTM, Philadelphia, PA, 1992, vol. 01.02, pp. 341–42Google Scholar
  22. 22.
    D. Krishnaraj, H.N.L. Narasimhan, S. Seshan: AFS Trans., 1992, vol. 100, pp. 105–12Google Scholar
  23. 23.
    ASTM A47M, Annual Book of ASTM Standard, ASTM, Philadelphia, PA, 1990, vol. 01.02, pp. 10–15Google Scholar
  24. 24.
    ASTM A220M, Annual Book of ASTM Standard, ASTM, Philadelphia, PA, 1988, vol. 01.02, pp. 123–28Google Scholar

Copyright information

© THE MINERALS, METALS & MATERIALS SOCIETY and ASM INTERNATIONAL 2007

Authors and Affiliations

  1. 1.Department of Materials EngineeringTatung UniversityTaipeiTaiwan, Republic of China

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