Goodall, R. orcid.org/0000-0003-0720-9694, Utton, C., Gong, P. et al. (10 more authors) (2024) Development of a boron-containing reduced activation Ferritic-Martensitic (B-RAFM) steel. Ironmaking & Steelmaking: Processes, Products and Applications. ISSN 0301-9233
Abstract
Steel will be an essential part of any commercial fusion reactor design. Applications in this area involve extreme conditions, imposing particular performance requirements, such as high operational temperature and creep resistance, and also a limitation on the elements that can be used due to the activation that occurs on interaction with irradiation. This work begins with a steel developed for conventional power plant applications, the IBN1 grade developed by IMPACT (a UK consortium of industrial and academic research organisations). This grade has shown excellent properties at high temperature due to high temperature-stable precipitate phases, but contains several elements that would become radiologically active to a degree that is incompatible with the required disposal routes after exposure to the fusion reactor environment. In this study, modifications of the composition are made to remove these elements, and thermodynamic modelling and experimental assessment of the phases that form are undertaken. In this, we have paid particular attention to the prediction of transformation temperatures (to understand if normalisation and tempering can be applied successfully) and the precipitates, to see if suitable phases that are likely to impart creep strength and other desirable properties would be formed. The modifications made include the removal of Nb, Mo, Ni, Co, Cu and Al from the starting alloy, and the substitution of Ta (intended to form carbides, replacing the effect of Nb). Modifications of the amount of retained elemental components, such as C, Mn and Cr, have been made with Thermo-Calc modelling, to ensure preservation of comparable phase transformation temperatures and microstructures. The predicted changes to the alloy are compared to the observations from experimental investigation, finding that tantalum can substitute for niobium in these systems and form similar carbides with similar distribution in the material, and that reduction of Cr to 8 wt% and increase of C to 0.12 wt% raises the Ae<jats:sub>4</jats:sub> temperature to allow a high-temperature heat treatment without δ-ferrite formation. While assessment of the mechanical properties of this alloy would be required, the perspectives for these alloys to perform at high temperature that can be inferred from the microstructure are discussed.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2024 The Authors. This is an Open Access article distributed under the terms of the Creative Commons Attribution Licence (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. |
Keywords: | alloy design; reduced activation steels; CALPHAD; microstructure; fusion materials |
Dates: |
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Institution: | The University of Sheffield |
Academic Units: | The University of Sheffield > Faculty of Engineering (Sheffield) > School of Chemical, Materials and Biological Engineering |
Funding Information: | Funder Grant number Engineering and Physical Sciences Research Council EP/P02470X/1 Engineering and Physical Sciences Research Council EP/P025285/1 Engineering and Physical Sciences Research Council EP/S019367/1 Engineering and Physical Sciences Research Council EP/R00661X/1 |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 11 Oct 2024 11:48 |
Last Modified: | 11 Oct 2024 11:48 |
Published Version: | http://dx.doi.org/10.1177/03019233241273484 |
Status: | Published online |
Publisher: | SAGE Publications |
Refereed: | Yes |
Identification Number: | 10.1177/03019233241273484 |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:218183 |