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Fatigue crack initiation and growth behavior within varying notch geometries in the low-cycle fatigue regime for FV566 turbine blade material

Fatigue crack initiation and growth behavior within varying notch geometries in the low-cycle fatigue regime for FV566 turbine blade material
Fatigue crack initiation and growth behavior within varying notch geometries in the low-cycle fatigue regime for FV566 turbine blade material

Plain bend bars made from FV566 martensitic stainless steel were extracted from the root of ex-service power plant turbine blades and several industry-relevant notch geometries were introduced. Some of the samples were shot peened. The notched bend bars were loaded plastically in the low-cycle fatigue regime and finite element (FE) modeling carried out to investigate the effects of changing notch geometry, combined with shot peening, on fatigue behaviors such as crack initiation, short crack growth, and coalescence. Shot peening damaged the notch surface, accelerating initiation behaviors, but had a lifetime-extending effect by retarding short crack growth in all tested notch geometries. At a total strain range higher than 1.2%, the lifetime extension benefit from shot peening was diminished due to compressive residual stress relaxation in the notch stress field. Notch geometry (and the associated varying constraint levels and stress/strain gradients) was found to have no notable difference on fatigue life when tested at identical notch-root strain ranges.

constant amplitude, low cycle fatigue, notch field, notches, short crack growth, stainless steel
8756-758X
2845-2863
Cunningham, Benjamin M.D.
429d7666-b076-4f03-b058-47d3e47bbba3
Leering, Mitchell
aa9c75e2-76c9-4f8e-badd-66e2bee32b70
Fan, Yuhui
61961875-7333-4f7a-8c27-20f1f4ce933a
You, Chao
1970d34b-ab33-4098-9363-2df30f36dda1
Morris, Andrew
11ac1caa-5a0e-4ecd-91ec-fa4273ba8c9a
Reed, Philippa A.S.
8b79d87f-3288-4167-bcfc-c1de4b93ce17
Hamilton, Andrew R.
9088cf01-8d7f-45f0-af56-b4784227447c
Fitzpatrick, Michael E.
f0f38563-0e99-45c1-9699-e4c488d15172
Cunningham, Benjamin M.D.
429d7666-b076-4f03-b058-47d3e47bbba3
Leering, Mitchell
aa9c75e2-76c9-4f8e-badd-66e2bee32b70
Fan, Yuhui
61961875-7333-4f7a-8c27-20f1f4ce933a
You, Chao
1970d34b-ab33-4098-9363-2df30f36dda1
Morris, Andrew
11ac1caa-5a0e-4ecd-91ec-fa4273ba8c9a
Reed, Philippa A.S.
8b79d87f-3288-4167-bcfc-c1de4b93ce17
Hamilton, Andrew R.
9088cf01-8d7f-45f0-af56-b4784227447c
Fitzpatrick, Michael E.
f0f38563-0e99-45c1-9699-e4c488d15172

Cunningham, Benjamin M.D., Leering, Mitchell, Fan, Yuhui, You, Chao, Morris, Andrew, Reed, Philippa A.S., Hamilton, Andrew R. and Fitzpatrick, Michael E. (2023) Fatigue crack initiation and growth behavior within varying notch geometries in the low-cycle fatigue regime for FV566 turbine blade material. Fatigue & Fracture of Engineering Materials & Structures, 46 (8), 2845-2863. (doi:10.1111/ffe.14036).

Record type: Article

Abstract

Plain bend bars made from FV566 martensitic stainless steel were extracted from the root of ex-service power plant turbine blades and several industry-relevant notch geometries were introduced. Some of the samples were shot peened. The notched bend bars were loaded plastically in the low-cycle fatigue regime and finite element (FE) modeling carried out to investigate the effects of changing notch geometry, combined with shot peening, on fatigue behaviors such as crack initiation, short crack growth, and coalescence. Shot peening damaged the notch surface, accelerating initiation behaviors, but had a lifetime-extending effect by retarding short crack growth in all tested notch geometries. At a total strain range higher than 1.2%, the lifetime extension benefit from shot peening was diminished due to compressive residual stress relaxation in the notch stress field. Notch geometry (and the associated varying constraint levels and stress/strain gradients) was found to have no notable difference on fatigue life when tested at identical notch-root strain ranges.

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B Cunningham paper 3 - Draft V2 - Author's Original
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B Cunningham FFEMS Paper 2 final - Accepted Manuscript
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Fatigue Fract Eng Mat Struct - 2023 - Cunningham - Fatigue crack initiation and growth behavior within varying notch - Version of Record
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More information

Accepted/In Press date: 23 April 2023
e-pub ahead of print date: 16 May 2023
Additional Information: This study is financially supported by the Engineering and Physical Sciences Research Council (EPSRC), UK (Grant EP/N509747/1). The authors would like to acknowledge the funding and support of the University of Southampton. We would also like to thank EDF energy for providing ex-service blade material and industrial co-funding for this project. C. You would like to acknowledge the funding and support from Natural Science Foundation of Jiangsu Province (Grant BK20210302). For the purpose of open access, the author has applied a CC BY public copyright licence to any Author Accepted Manuscript version arising from this submission. MEF wishes to acknowledge the support of the Lloyd’s Register Foundation, a charitable foundation helping protect life and property by supporting engineering-related education, public engagement, and the application of research.
Keywords: constant amplitude, low cycle fatigue, notch field, notches, short crack growth, stainless steel

Identifiers

Local EPrints ID: 476501
URI: http://eprints.soton.ac.uk/id/eprint/476501
ISSN: 8756-758X
PURE UUID: 3c3702cb-4c2c-4504-af5e-dc2dd1d12194
ORCID for Benjamin M.D. Cunningham: ORCID iD orcid.org/0000-0002-2604-4242
ORCID for Chao You: ORCID iD orcid.org/0000-0003-0118-0771
ORCID for Philippa A.S. Reed: ORCID iD orcid.org/0000-0002-2258-0347
ORCID for Andrew R. Hamilton: ORCID iD orcid.org/0000-0003-4627-849X

Catalogue record

Date deposited: 04 May 2023 17:01
Last modified: 12 Jun 2024 02:06

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Contributors

Author: Benjamin M.D. Cunningham ORCID iD
Author: Mitchell Leering
Author: Yuhui Fan
Author: Chao You ORCID iD
Author: Andrew Morris
Author: Michael E. Fitzpatrick

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