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Effects of oxygen-related damage on dwell-fatigue crack propagation in a P/M Ni-based superalloy: From 2D to 3D assessment

Effects of oxygen-related damage on dwell-fatigue crack propagation in a P/M Ni-based superalloy: From 2D to 3D assessment
Effects of oxygen-related damage on dwell-fatigue crack propagation in a P/M Ni-based superalloy: From 2D to 3D assessment
Effects of oxygen-related damage (i.e. oxidation and dynamic embrittlement) on fatigue crack propagation behavior in an advanced disc alloy have been assessed in air and vacuum under dwell-fatigue conditions at 725 °C. The enhanced fatigue crack propagation is closely related to oxygen-related damage at/ahead of the crack tip, which is determined by the testing environment, the dwell period and the crack propagation rate itself based on two dimensional (2D) observation of the crack tip in an optical microscope and scanning electron microscope. X-ray computed tomography has also been employed to examine the differences between three dimension (3D) crack morphology in air and vacuum conditions, and the crack features have been quantified in terms of crack opening displacements, secondary cracks and uncracked bridging ligaments. The results show that the fatigue crack propagation rate is related to the amount of secondary cracks, and the crack length increment in a loading cycle is related to the breaking/cracking of the uncracked bridging ligaments within the discontinuous cracking zone ahead of the crack tip as oxygen-related damage preferentially occurs in these highly deformed regions. By combination of 3D X-ray computed tomography and traditional 2D observation, a deeper understanding is provided of the mechanisms of oxygen-enhanced fatigue crack propagation behavior.
Ni-based superalloys; Fatigue crack propagation rate; Oxygen-related damage; X-ray computed tomography; Secondary cracks
175-186
Jiang, Rong
1e3a7913-c354-4ecb-879c-526cb6fe5fcd
Bull, Daniel
3569ba02-89de-4398-a14d-02c3f9b4eab2
Proprentner, D.
d7dad0a3-76ff-42cb-a2f4-6126d3c30a60
Shollock, B.
c29842be-ea75-47b4-a92d-402486d66331
Reed, Philippa
8b79d87f-3288-4167-bcfc-c1de4b93ce17
Jiang, Rong
1e3a7913-c354-4ecb-879c-526cb6fe5fcd
Bull, Daniel
3569ba02-89de-4398-a14d-02c3f9b4eab2
Proprentner, D.
d7dad0a3-76ff-42cb-a2f4-6126d3c30a60
Shollock, B.
c29842be-ea75-47b4-a92d-402486d66331
Reed, Philippa
8b79d87f-3288-4167-bcfc-c1de4b93ce17

Jiang, Rong, Bull, Daniel, Proprentner, D., Shollock, B. and Reed, Philippa (2017) Effects of oxygen-related damage on dwell-fatigue crack propagation in a P/M Ni-based superalloy: From 2D to 3D assessment. International Journal of Fatigue, 99, 175-186. (doi:10.1016/j.ijfatigue.2017.03.003).

Record type: Article

Abstract

Effects of oxygen-related damage (i.e. oxidation and dynamic embrittlement) on fatigue crack propagation behavior in an advanced disc alloy have been assessed in air and vacuum under dwell-fatigue conditions at 725 °C. The enhanced fatigue crack propagation is closely related to oxygen-related damage at/ahead of the crack tip, which is determined by the testing environment, the dwell period and the crack propagation rate itself based on two dimensional (2D) observation of the crack tip in an optical microscope and scanning electron microscope. X-ray computed tomography has also been employed to examine the differences between three dimension (3D) crack morphology in air and vacuum conditions, and the crack features have been quantified in terms of crack opening displacements, secondary cracks and uncracked bridging ligaments. The results show that the fatigue crack propagation rate is related to the amount of secondary cracks, and the crack length increment in a loading cycle is related to the breaking/cracking of the uncracked bridging ligaments within the discontinuous cracking zone ahead of the crack tip as oxygen-related damage preferentially occurs in these highly deformed regions. By combination of 3D X-ray computed tomography and traditional 2D observation, a deeper understanding is provided of the mechanisms of oxygen-enhanced fatigue crack propagation behavior.

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1-s2.0-S0142112317300907-main - Accepted Manuscript
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More information

Accepted/In Press date: 3 March 2017
Published date: 1 June 2017
Keywords: Ni-based superalloys; Fatigue crack propagation rate; Oxygen-related damage; X-ray computed tomography; Secondary cracks
Organisations: Engineering Mats & Surface Engineerg Gp, Engineering Science Unit

Identifiers

Local EPrints ID: 406520
URI: http://eprints.soton.ac.uk/id/eprint/406520
PURE UUID: 5f368924-c97c-4774-a0b1-0d48ced02b00
ORCID for Daniel Bull: ORCID iD orcid.org/0000-0001-6711-6153
ORCID for Philippa Reed: ORCID iD orcid.org/0000-0002-2258-0347

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Date deposited: 18 Mar 2017 02:21
Last modified: 06 Jun 2024 04:07

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Contributors

Author: Rong Jiang
Author: Daniel Bull ORCID iD
Author: D. Proprentner
Author: B. Shollock
Author: Philippa Reed ORCID iD

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