Title
Interaction of precipitation with austenite-to-ferrite phase transformation in vanadium micro-alloyed steels
Author
Ioannidou, C. (TU Delft (OLD) MSE-1)
Arechabaleta Guenechea, Z. (TU Delft (OLD) MSE-1)
Navarro Lopez, A. (TU Delft (OLD) MSE-1) 
Rijkenberg, Arjan (Tata Steel, 1970 CA IJmuiden, the Netherlands)
Dalgliesh, Robert M. (Rutherford Appleton Laboratory)
Kölling, S. (Eindhoven University of Technology)
Bliznuk, Vitaliy (Universiteit Gent)
Pappas, C. (TU Delft RST/Neutron and Positron Methods in Materials)
Sietsma, J. (TU Delft Materials Science and Engineering)
van Well, A.A. (TU Delft Bedrijfsondersteuning)
Offerman, S.E. (TU Delft (OLD) MSE-1)
Department
Materials Science and Engineering
Date
2019
Abstract
The precipitation kinetics of vanadium carbides and its interaction with the austenite-to-ferrite phase transformation is studied in two micro-alloyed steels that differ in vanadium and carbon concentrations by a factor of two, but have the same vanadium-to-carbon atomic ratio of 1:1. Dilatometry is used for heat-treating the specimens and studying the phase transformation kinetics during annealing at isothermal holding temperatures of 900, 750 and 650 °C for up to 10 h. Small-Angle Neutron Scattering (SANS) and Atom Probe Tomography (APT) measurements are performed to study the vanadium carbide precipitation kinetics. Vanadium carbide precipitation is not observed after annealing for 10 h at 900 and 750 °C, which is contrary to predictions from thermodynamic equilibrium calculations. Vanadium carbide precipitation is only observed during or after the austenite-to-ferrite phase transformation at 650 °C. The precipitate volume fraction and mean radius continuously increase as holding time increases, while the precipitate number density starts to decrease after 20 min, which corresponds to the time at which the austenite-to-ferrite phase transformation is finished. This indicates that nucleation and growth are dominant during the first 20 min, while later precipitate growth with soft impingement (overlapping diffusion fields) and coarsening take place. APT shows gradual changes in the precipitate chemical composition during annealing at 650 °C, which finally reaches a 1:1 atomic ratio of vanadium-to-carbon in the core of the precipitates after 10 h.
Subject
Micro-alloyed steel
Vanadium carbide interphase precipitation
Austenite-to-ferrite phase transformation kinetics
Small-angle neutron scattering
Atom Probe Tomography
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http://resolver.tudelft.nl/uuid:dfce1494-0fd6-4785-ad1a-2d3bf4933fdf
DOI
https://doi.org/10.1016/j.actamat.2019.09.046
Embargo date
2020-03-26
ISSN
1359-6454
Source
Acta Materialia, 181, 10-24
Bibliographical note
Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.
Part of collection
Institutional Repository
Document type
journal article
Rights
© 2019 C. Ioannidou, Z. Arechabaleta Guenechea, A. Navarro Lopez, Arjan Rijkenberg, Robert M. Dalgliesh, S. Kölling, Vitaliy Bliznuk, C. Pappas, J. Sietsma, A.A. van Well, S.E. Offerman