University of Oulu

Forouzan, F.; Surki Aliabad, R.; Hedayati, A.; Hosseini, N.; Maawad, E.; Blasco, N.; Vuorinen, E. Kinetics of Carbon Enrichment in Austenite during Partitioning Stage Studied via In-Situ Synchrotron XRD. Materials 2023, 16, 1557.

Kinetics of carbon enrichment in austenite during partitioning stage studied via in-situ synchrotron XRD

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Author: Forouzan, Farnoosh1; Surki Aliabad, Roohallah2; Hedayati, Ali1;
Organizations: 1Department of Engineering Sciences and Mathematics, Luleå University of Technology, SE-97187 Luleå, Sweden
2Materials and Mechanical Engineering, University of Oulu, 90014 Oulu, Finland
3Helmholtz-Zentrum Hereon, Institute of Materials Physics, Max-Planck-Straße 1, 21502 Geesthacht, Germany
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 4.9 MB)
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Language: English
Published: Multidisciplinary Digital Publishing Institute, 2023
Publish Date: 2023-08-10


The present study reveals the microstructural evolution and corresponding mechanisms occurring during different stages of quenching and partitioning (Q&P) conducted on 0.6C-1.5Si steel using in-situ High Energy X-Ray Diffraction (HEXRD) and high-resolution dilatometry methods. The results support that the symmetry of ferrite is not cubic when first formed since it is fully supersaturated with carbon at the early stages of partitioning. Moreover, by increasing partitioning temperature, the dominant carbon source for austenite enrichment changes from ongoing bainitic ferrite transformation during the partitioning stage to initial martensite formed in the quenching stage. At low partitioning temperatures, a bimodal distribution of low- and high-carbon austenite, 0.6 and 1.9 wt.% carbon, is detected. At higher temperatures, a better distribution of carbon occurs, approaching full homogenization. An initial martensite content of around 11.5 wt.% after partitioning at 280 °C via bainitic ferrite transformation results in higher carbon enrichment of austenite and increased retained austenite amount by approximately 4% in comparison with partitioning at 500 °C. In comparison with austempering heat treatment with no prior martensite, the presence of initial martensite in the Q&P microstructure accelerates the subsequent low-temperature bainitic transformation.

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Series: Materials
ISSN: 1996-1944
ISSN-E: 1996-1944
ISSN-L: 1996-1944
Volume: 16
Issue: 4
Article number: 1557
DOI: 10.3390/ma16041557
Type of Publication: A1 Journal article – refereed
Field of Science: 216 Materials engineering
Funding: This research has been partly funded by the Kempe Foundation, Sweden. R. Surki Aliabad would also like to thank Jane and Aatos Erkon säätiö (JAES) and Tiina ja Antti Herlinin säätiö (TAHS) for their financial supports on Advanced Steels for Green Planet Project.
Copyright information: © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (