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Journal of Materials Engineering and Performance

, Volume 21, Issue 8, pp 1785–1792 | Cite as

The Effect of Isothermal Heat Treatment Time on the Microstructure and Properties of 2.11% Al Austempered Ductile Iron

  • H. R. Erfanian-Naziftoosi
  • N. Haghdadi
  • A. R. Kiani-RashidEmail author
Article

Abstract

In this article, the bainitic transformation during austempering was studied for a 2.11% Al containing ductile iron under different isothermal holding times. The austenitizing time and temperature were selected to be 60 min and 920 °C, respectively, referring to previous studies. The isothermal austempering heat treatments were performed at 350 °C for different durations. Microstructures have been examined by optical microscopy, scanning electron microscopy, and transmission electron microscopy. Microstructural investigations revealed that austempering treatment at 350 °C for durations up to 100 min results in microstructures consisting of carbide-free bainitic ferrite with considerable amounts of retained austenite while the extension of isothermal transformation time leads to precipitation of carbides. Hardness measurements were also carried out the results of which were shown to be consistent with microstructural evolutions.

Keywords

austempering bainite ductile iron SEM TEM 

Notes

Acknowledgments

The authors wish to thank Mr. B. Bazaz and Mrs. A.T. Yazdi for their worthy assists. We would also like to express our sincere thanks to Professor D.V. Edmonds at the Materials Department of University of Leeds for his valuable support in electron microscopy.

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Copyright information

© ASM International 2011

Authors and Affiliations

  • H. R. Erfanian-Naziftoosi
    • 1
  • N. Haghdadi
    • 1
  • A. R. Kiani-Rashid
    • 1
    Email author
  1. 1.Department of Materials Engineering, Faculty of EngineeringFerdowsi University of MashhadMashhadIran

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