In situ TEM observations of the growth of bainitic ferrite in an Fe-0.3C-3Mn-1.5Si-0.15Mo steel

Journal article (2023)

Authors

J. Nutter University of Sheffield
Jiahui Qi University of Sheffield
H. Farahani Team Maria Santofimia Navarro - Mechanical, Maritime and Materials Engineering , Tata Steel Europe Limited
W. M. Rainforth University of Sheffield
S. van der Zwaag Novel Aerospace Materials - Aerospace Engineering
Research Group
Team Maria Santofimia Navarro (Mechanical, Maritime and Materials Engineering) (TU Delft)
Copyright: © 2023 John Nutter, Jiahui Qi, H. Farahani, W. Mark Rainforth, S. van der Zwaag
DOI: https://doi.org/10.1016/j.actamat.2023.118924
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Published Date

2023

Language

English

Faculty

Mechanical, Maritime and Materials Engineering

Department

Materials Science and Engineering

Research Group

Team Maria Santofimia Navarro

Abstract

The current study reports in situ TEM observations of the growth of bainitic ferrite in an Fe-0.3C-3Mn-1.5Si-0.15Mo steel held isothermally at 300 °C with a higher spatio-temporal resolution than in previous studies. Significant variations were found in the lengthening rate, with the highest being in excess of 30,000 nm.s−1 while more common lengthening rates of 10–1000 nm.s−1 provided the highest quality observations. Both sheaves with visible sub units and individual laths were observed during growth with the lengthening behaviour of sheaves found to be discontinuous - in the most favourably oriented sheave this could be linked to sub unit behaviour. The transformation behaviour was comparable to that of HT-LSCM observations of bainitic ferrite growth for the most comparable steel compositions and to ‘textbook’ descriptions of the formation of bainite sheaves. In addition, other relevant phenomena were recorded, including the generation and movement of dislocations in the austenite during transformation, the interaction of laths with twin boundaries and the initially slow growth of bainitic ferrite laths.