University of Oulu

Mohammad R. Kamali, Ali R. Mashreghi, L. Pentti Karjalainen, Saeed Hasani, Vahid Javaheri, Sami Saukko, Jukka Kömi, Reobservations on ordering, precipitation and polymorphic phase transformation phenomena during annealing of a severely cold rolled magnetic Fe-Co-10V alloy, Materialia, Volume 12, 2020, 100765, ISSN 2589-1529,

Reobservations on ordering, precipitation and polymorphic phase transformation phenomena during annealing of a severely cold rolled magnetic Fe-Co-10V alloy

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Author: Kamali, Mohammad R.1,2; Mashreghi, Ali R.2; Karjalainen, L. Pentti1;
Organizations: 1Materials and Mechanical Engineering unit, Centre for Advanced Steels Research, Box 4200, University of Oulu, FI-90014 Oulu, Finland
2Department of Mining and Metallurgical Engineering, Yazd University, Yazd, Iran
3Centre for Material Analysis, University of Oulu, FI-90014 Oulu, Finland
Format: article
Version: accepted version
Access: open
Online Access: PDF Full Text (PDF, 5.3 MB)
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Language: English
Published: Elsevier, 2020
Publish Date: 2022-06-12


Despite extensive investigations conducted on magnetic Fe-Co-V alloys, some aspects of microstructural evolution during annealing of cold rolled sheets have not yet been clarified yet. Various techniques such as dilatometry, X-ray diffraction (XRD), transmission and scanning electron microscopy (TEM, SEM) as well as ThermoCalc predictions were employed to study ordering, precipitation and austenite transformation in an 86% cold-rolled 40Fe-50Co-10 V alloy. Dilatometric results revealed atomic ordering initiated from disordered martensite at 350 °C, while XRD patterns ascertained the completion of the process at 600 °C and its disappearance close to 750 °C. X-ray and electron diffraction patterns exhibited the B2 type ordered structure in this temperature range. Rod-shaped precipitates with HCP crystalline structure and the constant composition of (Co,Fe)₃ V were detected by SEM within the deformed ferrite grains after annealing in the temperature range of 500–700 °C. The percentage of the precipitates decreased by raising the annealing temperature and they vanished above 700 °C, in accordance with ThermoCalc prediction. Austenite grains formed below 750 °C had an ordered L1₂-type structure as revealed by TEM and XRD patterns. A combination of different techniques demonstrated that the two-phase ferrite-austenite region exists in the temperature range of 495–840 °C. Vanadium partitioning into austenite during isothermal holding in addition to austenite grain size were evaluated as the main parameters affecting austenite stability during quenching from temperatures between 500 and 800 °C. As a final result, most of the existing disagreements and ambiguities in previous works could be explained.

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Series: Materialia
ISSN: 2589-1529
ISSN-E: 2589-1529
ISSN-L: 2589-1529
Volume: 12
Article number: 100765
DOI: 10.1016/j.mtla.2020.100765
Type of Publication: A1 Journal article – refereed
Field of Science: 216 Materials engineering
Funding: MRK is grateful for financial support from the Iranian government for his research stay at the University of Oulu and for facilities and equipment provided by the University of Oulu for performing this study. LPK, VJ and JK acknowledge the support of the Academy of Finland for the “Genome of Steel” project #311934.
Copyright information: © 2020 Acta Materialia Inc. Published by Elsevier B.V. This manuscript version is made available under the CC-BY-NC-ND 4.0 license