University of Oulu

Shima Pashangeh, Mahesh Somani, Seyyed Sadegh Ghasemi Banadkouki, Microstructural evolution in a high-silicon medium carbon steel following quenching and isothermal holding above and below the Ms temperature, Journal of Materials Research and Technology, Volume 9, Issue 3, 2020, Pages 3438-3446, ISSN 2238-7854, https://doi.org/10.1016/j.jmrt.2020.01.081

Microstructural evolution in a high-silicon medium carbon steel following quenching and isothermal holding above and below the Ms temperature

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Author: Pashangeh, Shima1,2; Somani, Mahesh2; Banadkouki, Seyyed Sadegh Ghasemi1
Organizations: 1Mining Technologies Research Center, Department of Mining and Metallurgical Engineering, Yazd University, University Blvd, Safayieh, Yazd, PO Box: 98195 – 741, Iran
2University of Oulu, Materials and Mechanical Engineering, Centre for Advanced Steels Research, P.O. Box 4200, 90014 Oulu, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 3.2 MB)
Persistent link: http://urn.fi/urn:nbn:fi-fe2020090367358
Language: English
Published: Elsevier, 2020
Publish Date: 2020-09-03
Description:

Abstract

In this study, the microstructural features evolved in a high-Si, medium-carbon steel (Fe-0.53C-1.67Si-0.72Mn-0.12Cr) subjected to quenching and isothermal holding at temperatures above and below the martensite start temperature (Ms) for one hour have been examined. Both laser scanning confocal and transmission electron microscopy were employed for detailed microstructural characterization, supported by dilatometry, X-ray diffraction, and hardness measurements. In the case of isothermal treatment above Ms at 300 °C, besides bainite transformation marked by typical S-shaped dilatation curve, high-carbon martensite is formed during the final cooling to room temperature. In the case of isothermal treatment below Ms at 250 °C, the initial martensite formation and subsequent carbon partitioning to austenite is followed by the formation of bainite containing carbides and some high-carbon martensite that forms during the final cooling to room temperature. Also, selected area diffraction patterns (SAED) for both of Q&B and Q&P heat treated samples showed there are extra weak diffraction spots, presumably due to the presence of omega phase (ω) as an intermediate phase during fcc (face- centered cubic) austenite to bcc (body- centered cubic) martensite transformation and is considered as a common substructure in bcc metals and alloys with a coherent interface with the matrix: aω = √2 × abcc and caω = √3/2 × abcc that appeared in twinning martensite or martensite regions with dislocations as a substructure.

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Series: Journal of materials research and technology
ISSN: 2238-7854
ISSN-E: 2214-0697
ISSN-L: 2238-7854
Volume: 9
Issue: 3
Pages: 3438 - 3446
DOI: 10.1016/j.jmrt.2020.01.081
OADOI: https://oadoi.org/10.1016/j.jmrt.2020.01.081
Type of Publication: A1 Journal article – refereed
Field of Science: 216 Materials engineering
Subjects:
Funding: The funding of this research activity under the auspices of the Genome of Steel Profi3 by the Academy of Finland through project #311934 is gratefully acknowledged. S. Pashangeh expresses her gratitude to the Ministry of Science Research and Technology in Iran for funding a research visit to the University of Oulu, Finland to conduct this research work. Authors would like to thank Mr. Sami Saukko, University of Oulu for conducting the TEM examination and holding scientific discussions.
Copyright information: © 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
  https://creativecommons.org/licenses/by-nc-nd/4.0/