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Fatigue crack initiation and growth behavior in a notch with periodic overloads in the low-cycle fatigue regime of FV566 ex-service steam turbine blade material

Fatigue crack initiation and growth behavior in a notch with periodic overloads in the low-cycle fatigue regime of FV566 ex-service steam turbine blade material
Fatigue crack initiation and growth behavior in a notch with periodic overloads in the low-cycle fatigue regime of FV566 ex-service steam turbine blade material
The effect of periodic overloads on crack initiation, growth rate and fatigue life, within a notch stress field representative of a turbine blade root fixing has been investigated. Bend bars made from FV566 martensitic stainless steel were extracted from the root of ex-service power plant turbine blades and representative notches introduced. These notched plain bend bars were loaded plastically in the low cycle fatigue regime and were tested with overloads up to 150% of the cyclic baseload every 150 baseload cycles. A periodic overload of 50% of the cyclic baseload increased the number of cycles to crack initiation and slightly retarded the crack growth rates of both short and long cracks, leading to a slight improvement in fatigue life. The results suggest that small overloads (less than 10%) are not expected to significantly impact fatigue lifetimes or service scheduling of components such as Low Pressure steam turbine blades.
fatigue crack growth, long cracks, notches, overloads, short cracks, stainless steel
8756-758X
546-564
Cunningham, Benjamin M. D.
429d7666-b076-4f03-b058-47d3e47bbba3
Evangelou, Angelos
840a9ab3-d2f9-4dee-9d5a-9f9c18c43be8
You, Chao
1970d34b-ab33-4098-9363-2df30f36dda1
Morris, Andrew
00ef3bfb-219c-4ea7-86d2-dd4d71c083a6
Wise, James
03a91e3c-f115-48de-8a8d-16758b005acb
Reed, Philippa A. S.
8b79d87f-3288-4167-bcfc-c1de4b93ce17
Hamilton, Andrew R.
9088cf01-8d7f-45f0-af56-b4784227447c
Cunningham, Benjamin M. D.
429d7666-b076-4f03-b058-47d3e47bbba3
Evangelou, Angelos
840a9ab3-d2f9-4dee-9d5a-9f9c18c43be8
You, Chao
1970d34b-ab33-4098-9363-2df30f36dda1
Morris, Andrew
00ef3bfb-219c-4ea7-86d2-dd4d71c083a6
Wise, James
03a91e3c-f115-48de-8a8d-16758b005acb
Reed, Philippa A. S.
8b79d87f-3288-4167-bcfc-c1de4b93ce17
Hamilton, Andrew R.
9088cf01-8d7f-45f0-af56-b4784227447c

Cunningham, Benjamin M. D., Evangelou, Angelos, You, Chao, Morris, Andrew, Wise, James, Reed, Philippa A. S. and Hamilton, Andrew R. (2021) Fatigue crack initiation and growth behavior in a notch with periodic overloads in the low-cycle fatigue regime of FV566 ex-service steam turbine blade material. Fatigue & Fracture of Engineering Materials & Structures, 45 (2), 546-564. (doi:10.1111/ffe.13617).

Record type: Article

Abstract

The effect of periodic overloads on crack initiation, growth rate and fatigue life, within a notch stress field representative of a turbine blade root fixing has been investigated. Bend bars made from FV566 martensitic stainless steel were extracted from the root of ex-service power plant turbine blades and representative notches introduced. These notched plain bend bars were loaded plastically in the low cycle fatigue regime and were tested with overloads up to 150% of the cyclic baseload every 150 baseload cycles. A periodic overload of 50% of the cyclic baseload increased the number of cycles to crack initiation and slightly retarded the crack growth rates of both short and long cracks, leading to a slight improvement in fatigue life. The results suggest that small overloads (less than 10%) are not expected to significantly impact fatigue lifetimes or service scheduling of components such as Low Pressure steam turbine blades.

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Submitted date: 20 September 2021
Accepted/In Press date: 2 November 2021
e-pub ahead of print date: 15 November 2021
Published date: 15 November 2021
Additional Information: Funding 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 and Southdown Materials Testing for carrying out spectrographic analysis of the ex-service blade material.
Keywords: fatigue crack growth, long cracks, notches, overloads, short cracks, stainless steel

Identifiers

Local EPrints ID: 452363
URI: http://eprints.soton.ac.uk/id/eprint/452363
ISSN: 8756-758X
PURE UUID: 5f408cf7-e592-438a-b4a8-0e5eb8b4fb47
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

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Date deposited: 08 Dec 2021 18:47
Last modified: 12 Jun 2024 02:06

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Contributors

Author: Benjamin M. D. Cunningham ORCID iD
Author: Angelos Evangelou
Author: Chao You ORCID iD
Author: Andrew Morris
Author: James Wise

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