University of Oulu

Shima Pashangeh, Mahesh Somani, Syyed Sadegh Ghasemi Banadkouki, Structure-Property Correlations of a Medium C Steel Following Quenching and Isothermal Holding above and below the Mₛ Temperature, ISIJ International, 2021, Volume 61, Issue 1, Pages 442-451, Released January 16, 2021, [Advance publication] Released September 28, 2020, Online ISSN 1347-5460, Print ISSN 0915-1559, https://doi.org/10.2355/isijinternational.ISIJINT-2020-355

Structure-property correlations of a medium C steel following quenching and isothermal holding above and below the Mₛ temperature

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Author: Pashangeh, Shima1,2; Somani, Mahesh1; Banadkouki, Syyed Sadegh Ghasemi2
Organizations: 1University of Oulu, Materials and Mechanical Engineering, Centre for Advanced Steels Research, P.O. Box 4200, 90014 Oulu, Finland
2Yazd University, Mining Technologies Research Center, Department of Mining and Metallurgical Engineering, P.O. Box 98195 – 741, University Blvd, Safayieh, Yazd, Ira
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 3.8 MB)
Persistent link: http://urn.fi/urn:nbn:fi-fe2021051429876
Language: English
Published: Iron and Steel Institute of Japan, 2021
Publish Date: 2021-05-14
Description:

Abstract

The processing of advanced multiphase high strength steels often includes isothermal treatments around the martensite start temperature (Ms) for achieving a refined microstructure comprising bainite-austenite and/or bainite-martensite-austenite phase constituents. The objective of this research work was to investigate the structure-property relationship for a medium carbon, high-silicon DIN 1.5025 steel (Fe-0.529C-1.67 Si-0.72Mn-0.12Cr (in wt.%)) following isothermal holding close to the Ms temperature (~275°C) to enable low temperature austenite decomposition. For realizing multiphase microstructures, DIN 1.5025 steel samples were austenitized at 900°C for 5 min and then quenched to the isothermal holding temperatures 350 and 250°C for various times ranging from 5 to 3600 s. Microstructural investigation corroborated the formation of multiphase microstructure comprising tempered martensite, bainite, retained austenite, and fresh martensite in both the samples isothermally held above (350°C) and below the Ms (250°C) temperature. The sample isothermally held at 250°C showed a much more refined microstructure in comparison to that held at 350°C due to the presence of a fraction of initial martensite laths which acted as potential sites for bainite nucleation. Also, the evaluation of mechanical behaviour showed that the best tensile properties in terms of high tensile strength and good ductility were achieved in samples with high volume fractions of both interlath and blocky retained austenite, particularly those isothermally treated at 350°C for 200 s and at 250°C for 600 s, respectively.

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Series: ISIJ international
ISSN: 0915-1559
ISSN-E: 1347-5460
ISSN-L: 0915-1559
Volume: 61
Issue: 1
Pages: 442 - 451
DOI: 10.2355/isijinternational.ISIJINT-2020-355
OADOI: https://oadoi.org/10.2355/isijinternational.ISIJINT-2020-355
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.
Copyright information: © 2021 The Iron and Steel Institute of Japan. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs license (https://creativecommons.org/licenses/by-nc-nd/4.0/).
  https://creativecommons.org/licenses/by-nc-nd/4.0/