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Effects of shot peening on short crack growth rate and resulting low cycle fatigue behaviour in low pressure turbine blade material

Effects of shot peening on short crack growth rate and resulting low cycle fatigue behaviour in low pressure turbine blade material
Effects of shot peening on short crack growth rate and resulting low cycle fatigue behaviour in low pressure turbine blade material
The effect of shot peening on subsequent low cycle fatigue behaviour of a representative low pressure steam turbine blade material has been investigated in bend test samples. An analysis of the short fatigue crack growth behaviour has been conducted. For samples with no stress concentration feature, shot peening was found to have a more evident beneficial effect at lower strain levels than at higher strain levels, whereas for samples with a stress concentration feature, the beneficial effect was retained even at higher strain levels. Preexisting cracks were observed on the shot peened surface, which started to grow at 10–25% of fatigue life in the low cycle fatigue regime. The crack propagation rate was slower than that observed in the ground sample, suggesting that the shot peening process delayed crack propagation. This improvement in fatigue life has been attributed to the significant slowing of small cracks while growing through surface regions of significant compressive residual stresses and local work hardening developed by the shot peening process. Once cracks in the notch root have penetrated this region in the depth direction, faster crack growth rates, similar to those observed in the ground case, were seen.
Low cycle fatigue, Shot peening, Residual stress, Short crack initiation and propagation, Ferritic heat resisting steel
0267-0836
788-796
He, B.
efdbea3e-018a-4db0-a3d8-629fb3ef5e54
Soady, K.A.
5a0739bd-5c9b-4b49-b4c7-105a79719a63
Mellor, B.G.
2b13b80f-880b-49ac-82fe-827a15dde2fe
Morris, A.
378f6b9c-92e7-4783-b7be-cafca74b5372
Reed, P.A.S.
8b79d87f-3288-4167-bcfc-c1de4b93ce17
He, B.
efdbea3e-018a-4db0-a3d8-629fb3ef5e54
Soady, K.A.
5a0739bd-5c9b-4b49-b4c7-105a79719a63
Mellor, B.G.
2b13b80f-880b-49ac-82fe-827a15dde2fe
Morris, A.
378f6b9c-92e7-4783-b7be-cafca74b5372
Reed, P.A.S.
8b79d87f-3288-4167-bcfc-c1de4b93ce17

He, B., Soady, K.A., Mellor, B.G., Morris, A. and Reed, P.A.S. (2013) Effects of shot peening on short crack growth rate and resulting low cycle fatigue behaviour in low pressure turbine blade material. Materials Science and Technology, 29 (7), 788-796. (doi:10.1179/1743284713Y.0000000230).

Record type: Article

Abstract

The effect of shot peening on subsequent low cycle fatigue behaviour of a representative low pressure steam turbine blade material has been investigated in bend test samples. An analysis of the short fatigue crack growth behaviour has been conducted. For samples with no stress concentration feature, shot peening was found to have a more evident beneficial effect at lower strain levels than at higher strain levels, whereas for samples with a stress concentration feature, the beneficial effect was retained even at higher strain levels. Preexisting cracks were observed on the shot peened surface, which started to grow at 10–25% of fatigue life in the low cycle fatigue regime. The crack propagation rate was slower than that observed in the ground sample, suggesting that the shot peening process delayed crack propagation. This improvement in fatigue life has been attributed to the significant slowing of small cracks while growing through surface regions of significant compressive residual stresses and local work hardening developed by the shot peening process. Once cracks in the notch root have penetrated this region in the depth direction, faster crack growth rates, similar to those observed in the ground case, were seen.

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Published date: July 2013
Keywords: Low cycle fatigue, Shot peening, Residual stress, Short crack initiation and propagation, Ferritic heat resisting steel
Organisations: Engineering Mats & Surface Engineerg Gp

Identifiers

Local EPrints ID: 351779
URI: http://eprints.soton.ac.uk/id/eprint/351779
ISSN: 0267-0836
PURE UUID: 586d54f4-2667-4893-86b2-8a1515d73b7a
ORCID for P.A.S. Reed: ORCID iD orcid.org/0000-0002-2258-0347

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Date deposited: 29 Apr 2013 12:28
Last modified: 15 Mar 2024 02:45

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Contributors

Author: B. He
Author: K.A. Soady
Author: B.G. Mellor
Author: A. Morris
Author: P.A.S. Reed ORCID iD

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