Title
Carbon solute drag effect on the growth of carbon supersaturated bainitic ferrite: Modeling and experimental validations
Author
Dai, Zongbiao (Xi’an Jiaotong University)
Chen, H. (TU Delft Novel Aerospace Materials; Tsinghua University)
Sun, Junjie (Xi’an Jiaotong University)
van der Zwaag, S. (TU Delft Group Garcia Espallargas) 
Sun, Jun (Xi’an Jiaotong University)
Date
2024
Abstract
The carbon partitioning and lengthening rate of bainitic ferrite (αb) are excellent experimental parameters to estimate our level of understanding of the mechanism of bainitic transformation from a continuum perspective and our ability to capture it in analytical expressions. For Fe-C alloys and relatively simple steels the classical Zener-Hillert theory captures the bainitic transformation rather well but mispredicts the level of carbon in solution in the bainite and overestimates the lengthening rates for transformations at lower temperatures. To address this issue, this paper presents a new thermo-kinetic model based on the Zener-Hillert theory and the Gibbs energy balance concept to simulate the lengthening behavior of αb in the Fe-C and low alloyed steels. The model incorporates the effect of the temperature dependent carbon diffusion within the migrating interface via a temperature dependent ferrite/austenite interfacial energy and a temperature dependent diffusion coefficient but does not impose local equilibrium across the interface. The good agreement between the model predictions and nine sets of published experiments indicates that both the carbon supersaturation in αb and the slower lengthening rate are caused by carbon diffusion within the migrating interface. It is found that the degree of carbon supersaturation in αb increases significantly with decreasing temperature. Consequently, the enhanced carbon solute drag effect, resulting from carbon diffusion within the interface, strongly retards the lengthening rates of αb at lower temperatures. Transformation strain is shown to have a modest effect on the lengthening rates but to lower the degree of carbon supersaturation.
Subject
Bainite formation
Carbon diffusion
Carbon supersaturation
Energy dissipation
Lengthening kinetics
To reference this document use:
http://resolver.tudelft.nl/uuid:62166ffb-ad44-4afc-aedd-234b9cd4a399
DOI
https://doi.org/10.1016/j.actamat.2024.119791
Embargo date
2024-09-02
ISSN
1359-6454
Source
Acta Materialia, 268
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
© 2024 Zongbiao Dai, H. Chen, Junjie Sun, S. van der Zwaag, Jun Sun