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Effects of microstructures on fatigue crack initiation and short crack propagation at room temperature in an advanced disc superalloy

Effects of microstructures on fatigue crack initiation and short crack propagation at room temperature in an advanced disc superalloy
Effects of microstructures on fatigue crack initiation and short crack propagation at room temperature in an advanced disc superalloy
Fatigue crack initiation and early short crack propagation behaviour in two microstructural variants of a recently developed Low Solvus, High Refractory (LSHR) disc superalloy at room temperature has been investigated by three-point bending with replication procedure. The results shows that fine gained (FG) LSHR possesses higher fatigue life due to its better crack initiation resistance, limited crack coalescence and comparable Stage I crack propagation resistance to the coarse grained (CG) LSHR, although its resistance to Stage II crack propagation is inferior. Twin boundary (TB) cracking in the relatively large grains dominates the crack initiation process along with occasional crack initiation due to slip band cracking. Activation of the primary slip systems parallel to the TB at matrix and twin and high resolved shear stress associated with high Schmid factor (SF) are required for TB crack initiation. Cracks preferentially propagate along slip bands associated with high SF slip systems after initiation. But cracks also propagate along slip bands associated with slip systems with lower SF if the inclination angle between the slip band ahead of the crack tip and the crack segment of the crack tip is small enough to enable a steady transition (or non-deflected growth) of cracks across the grain boundary.
Ni-based superalloys, twin boundary, schmid factor, slip band, fatigue cracking
0921-5093
148-159
Jiang, R.
b78f0919-0168-43cd-9cda-dd922d8776bf
Karpasitis, N.
289d3496-e04f-478e-a853-0117a76175bb
Gao, N.
9c1370f7-f4a9-4109-8a3a-4089b3baec21
Reed, P.A.S.
8b79d87f-3288-4167-bcfc-c1de4b93ce17
Jiang, R.
b78f0919-0168-43cd-9cda-dd922d8776bf
Karpasitis, N.
289d3496-e04f-478e-a853-0117a76175bb
Gao, N.
9c1370f7-f4a9-4109-8a3a-4089b3baec21
Reed, P.A.S.
8b79d87f-3288-4167-bcfc-c1de4b93ce17

Jiang, R., Karpasitis, N., Gao, N. and Reed, P.A.S. (2015) Effects of microstructures on fatigue crack initiation and short crack propagation at room temperature in an advanced disc superalloy. Materials Science and Engineering: A, 641, 148-159. (doi:10.1016/j.msea.2015.05.065).

Record type: Article

Abstract

Fatigue crack initiation and early short crack propagation behaviour in two microstructural variants of a recently developed Low Solvus, High Refractory (LSHR) disc superalloy at room temperature has been investigated by three-point bending with replication procedure. The results shows that fine gained (FG) LSHR possesses higher fatigue life due to its better crack initiation resistance, limited crack coalescence and comparable Stage I crack propagation resistance to the coarse grained (CG) LSHR, although its resistance to Stage II crack propagation is inferior. Twin boundary (TB) cracking in the relatively large grains dominates the crack initiation process along with occasional crack initiation due to slip band cracking. Activation of the primary slip systems parallel to the TB at matrix and twin and high resolved shear stress associated with high Schmid factor (SF) are required for TB crack initiation. Cracks preferentially propagate along slip bands associated with high SF slip systems after initiation. But cracks also propagate along slip bands associated with slip systems with lower SF if the inclination angle between the slip band ahead of the crack tip and the crack segment of the crack tip is small enough to enable a steady transition (or non-deflected growth) of cracks across the grain boundary.

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Accepted/In Press date: 21 May 2015
e-pub ahead of print date: 19 June 2015
Published date: 12 August 2015
Keywords: Ni-based superalloys, twin boundary, schmid factor, slip band, fatigue cracking
Organisations: Faculty of Engineering and the Environment

Identifiers

Local EPrints ID: 378781
URI: http://eprints.soton.ac.uk/id/eprint/378781
ISSN: 0921-5093
PURE UUID: 88f801d0-e181-495d-9f36-dd12ff4a0dac
ORCID for P.A.S. Reed: ORCID iD orcid.org/0000-0002-2258-0347

Catalogue record

Date deposited: 15 Jul 2015 09:04
Last modified: 17 Dec 2019 02:00

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Contributors

Author: R. Jiang
Author: N. Karpasitis
Author: N. Gao
Author: P.A.S. Reed ORCID iD

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