Influence of precipitate and grain sizes on the brittle-to-ductile transition in Fe–Al–V bcc-L21 ferritic superalloys

P. A. Ferreirós; U. A. Sterin; P. R. Alonso; A. J. Knowles; G. H. Rubiolo

doi:10.1016/j.msea.2022.144031

Influence of precipitate and grain sizes on the brittle-to-ductile transition in Fe–Al–V bcc-L2₁ ferritic superalloys

P. A. Ferreirós^*
, U. A. Sterin
, P. R. Alonso
, A. J. Knowles
, G. H. Rubiolo

^*Corresponding author for this work

Not published at VTT

University of Birmingham
Universidad Nacional de San Martín
Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)

Research output: Contribution to journal › Article › Scientific › peer-review

17 Citations (Scopus)

Abstract

The limiting factors to achieving a wide application of bcc-superalloys are the high brittle-to-ductile transition temperatures (BDTT). The understanding of the mechanisms controlling the BDTT and how to optimise the microstructure in polycrystalline bcc-superalloys remains a concern today. In the present work, the influence of grain and coherent precipitates sizes on strength and brittle-to-ductile transition temperature (BDTT) are studied in a Fe₇₈Al₁₀V₁₂ (A2+L2₁) ferritic superalloy, toward application in high-efficiency power plants. Additionally, the A2 matrix behaviour was evaluated in a derived single-phase-bcc Fe₈₄Al₈V₈ alloy. Thermal ageing and coarsening treatments were applied to produce samples with different precipitate and grain sizes. Tensile tests were carried out at different temperatures and strain rates to assess the variation of the yield stress. Charpy impact tests were used to measure the BDTT in both alloys, which was substantially reduced with grain size refinement, and precipitate coarsening. It was found that the increase in cleavage stress by precipitation strengthening follows the same behaviour that the increase in yield stress for coherent strengthened bcc-superalloys. Integration into a physical-based model, which identified a novel interplay with cleavage stress, provides enhanced BDTT predictive capability for ferritic superalloys.

Original language	English
Article number	144031
Journal	Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing
Volume	856
DOIs	https://doi.org/10.1016/j.msea.2022.144031
Publication status	Published - 20 Oct 2022
MoE publication type	A1 Journal article-refereed

Funding

The authors gratefully acknowledge the Centre for Electron Microscopy ( University of Birmingham ) for their support & assistance in this work. This research used internal founding of the Comisión Nacional de Energía Atómica. A.J. Knowles gratefully acknowledges funding from EPSRC [ EP/T016566/1 ], UKRI Future Leaders Fellowship [ MR/T019174/1 ] and Royal Academy of Engineering Research Fellowship, UK. U.A. Sterin was supported by Instituto Sabato & CONICET fellowships. The authors gratefully acknowledge the Centre for Electron Microscopy (University of Birmingham) for their support & assistance in this work. This research used internal founding of the Comisión Nacional de Energía Atómica. A.J. Knowles gratefully acknowledges funding from EPSRC [EP/T016566/1], UKRI Future Leaders Fellowship [MR/T019174/1] and Royal Academy of Engineering Research Fellowship, UK. U.A. Sterin was supported by Instituto Sabato & CONICET fellowships.

Keywords

Ageing
Brittle-to-ductile transition
Fe-Al-V
Impact test
Precipitate size
Superalloy

Access to Document

10.1016/j.msea.2022.144031Licence: CC BY

Cite this

Ferreirós, P. A., Sterin, U. A., Alonso, P. R., Knowles, A. J., & Rubiolo, G. H. (2022). Influence of precipitate and grain sizes on the brittle-to-ductile transition in Fe–Al–V bcc-L2₁ ferritic superalloys. Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing, 856, Article 144031. https://doi.org/10.1016/j.msea.2022.144031

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title = "Influence of precipitate and grain sizes on the brittle-to-ductile transition in Fe–Al–V bcc-L21 ferritic superalloys",

abstract = "The limiting factors to achieving a wide application of bcc-superalloys are the high brittle-to-ductile transition temperatures (BDTT). The understanding of the mechanisms controlling the BDTT and how to optimise the microstructure in polycrystalline bcc-superalloys remains a concern today. In the present work, the influence of grain and coherent precipitates sizes on strength and brittle-to-ductile transition temperature (BDTT) are studied in a Fe78Al10V12 (A2+L21) ferritic superalloy, toward application in high-efficiency power plants. Additionally, the A2 matrix behaviour was evaluated in a derived single-phase-bcc Fe84Al8V8 alloy. Thermal ageing and coarsening treatments were applied to produce samples with different precipitate and grain sizes. Tensile tests were carried out at different temperatures and strain rates to assess the variation of the yield stress. Charpy impact tests were used to measure the BDTT in both alloys, which was substantially reduced with grain size refinement, and precipitate coarsening. It was found that the increase in cleavage stress by precipitation strengthening follows the same behaviour that the increase in yield stress for coherent strengthened bcc-superalloys. Integration into a physical-based model, which identified a novel interplay with cleavage stress, provides enhanced BDTT predictive capability for ferritic superalloys.",

keywords = "Ageing, Brittle-to-ductile transition, Fe-Al-V, Impact test, Precipitate size, Superalloy",

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note = "Funding Information: The authors gratefully acknowledge the Centre for Electron Microscopy ( University of Birmingham ) for their support \& assistance in this work. This research used internal founding of the Comisi{\'o}n Nacional de Energ{\'i}a At{\'o}mica. A.J. Knowles gratefully acknowledges funding from EPSRC [ EP/T016566/1 ], UKRI Future Leaders Fellowship [ MR/T019174/1 ] and Royal Academy of Engineering Research Fellowship, UK. U.A. Sterin was supported by Instituto Sabato \& CONICET fellowships. Funding Information: The authors gratefully acknowledge the Centre for Electron Microscopy (University of Birmingham) for their support \& assistance in this work. This research used internal founding of the Comisi{\'o}n Nacional de Energ{\'i}a At{\'o}mica. A.J. Knowles gratefully acknowledges funding from EPSRC [EP/T016566/1], UKRI Future Leaders Fellowship [MR/T019174/1] and Royal Academy of Engineering Research Fellowship, UK. U.A. Sterin was supported by Instituto Sabato \& CONICET fellowships. Publisher Copyright: {\textcopyright} 2022 The Authors",

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doi = "10.1016/j.msea.2022.144031",

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Influence of precipitate and grain sizes on the brittle-to-ductile transition in Fe–Al–V bcc-L2₁ ferritic superalloys. / Ferreirós, P. A.; Sterin, U. A.; Alonso, P. R. et al.
In: Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing, Vol. 856, 144031, 20.10.2022.

Research output: Contribution to journal › Article › Scientific › peer-review

TY - JOUR

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AU - Ferreirós, P. A.

AU - Sterin, U. A.

AU - Alonso, P. R.

AU - Knowles, A. J.

AU - Rubiolo, G. H.

N1 - Funding Information: The authors gratefully acknowledge the Centre for Electron Microscopy ( University of Birmingham ) for their support & assistance in this work. This research used internal founding of the Comisión Nacional de Energía Atómica. A.J. Knowles gratefully acknowledges funding from EPSRC [ EP/T016566/1 ], UKRI Future Leaders Fellowship [ MR/T019174/1 ] and Royal Academy of Engineering Research Fellowship, UK. U.A. Sterin was supported by Instituto Sabato & CONICET fellowships. Funding Information: The authors gratefully acknowledge the Centre for Electron Microscopy (University of Birmingham) for their support & assistance in this work. This research used internal founding of the Comisión Nacional de Energía Atómica. A.J. Knowles gratefully acknowledges funding from EPSRC [EP/T016566/1], UKRI Future Leaders Fellowship [MR/T019174/1] and Royal Academy of Engineering Research Fellowship, UK. U.A. Sterin was supported by Instituto Sabato & CONICET fellowships. Publisher Copyright: © 2022 The Authors

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N2 - The limiting factors to achieving a wide application of bcc-superalloys are the high brittle-to-ductile transition temperatures (BDTT). The understanding of the mechanisms controlling the BDTT and how to optimise the microstructure in polycrystalline bcc-superalloys remains a concern today. In the present work, the influence of grain and coherent precipitates sizes on strength and brittle-to-ductile transition temperature (BDTT) are studied in a Fe78Al10V12 (A2+L21) ferritic superalloy, toward application in high-efficiency power plants. Additionally, the A2 matrix behaviour was evaluated in a derived single-phase-bcc Fe84Al8V8 alloy. Thermal ageing and coarsening treatments were applied to produce samples with different precipitate and grain sizes. Tensile tests were carried out at different temperatures and strain rates to assess the variation of the yield stress. Charpy impact tests were used to measure the BDTT in both alloys, which was substantially reduced with grain size refinement, and precipitate coarsening. It was found that the increase in cleavage stress by precipitation strengthening follows the same behaviour that the increase in yield stress for coherent strengthened bcc-superalloys. Integration into a physical-based model, which identified a novel interplay with cleavage stress, provides enhanced BDTT predictive capability for ferritic superalloys.

AB - The limiting factors to achieving a wide application of bcc-superalloys are the high brittle-to-ductile transition temperatures (BDTT). The understanding of the mechanisms controlling the BDTT and how to optimise the microstructure in polycrystalline bcc-superalloys remains a concern today. In the present work, the influence of grain and coherent precipitates sizes on strength and brittle-to-ductile transition temperature (BDTT) are studied in a Fe78Al10V12 (A2+L21) ferritic superalloy, toward application in high-efficiency power plants. Additionally, the A2 matrix behaviour was evaluated in a derived single-phase-bcc Fe84Al8V8 alloy. Thermal ageing and coarsening treatments were applied to produce samples with different precipitate and grain sizes. Tensile tests were carried out at different temperatures and strain rates to assess the variation of the yield stress. Charpy impact tests were used to measure the BDTT in both alloys, which was substantially reduced with grain size refinement, and precipitate coarsening. It was found that the increase in cleavage stress by precipitation strengthening follows the same behaviour that the increase in yield stress for coherent strengthened bcc-superalloys. Integration into a physical-based model, which identified a novel interplay with cleavage stress, provides enhanced BDTT predictive capability for ferritic superalloys.

KW - Ageing

KW - Brittle-to-ductile transition

KW - Fe-Al-V

KW - Impact test

KW - Precipitate size

KW - Superalloy

UR - https://www.scopus.com/pages/publications/85138386669

U2 - 10.1016/j.msea.2022.144031

DO - 10.1016/j.msea.2022.144031

M3 - Article

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JO - Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing

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