Deflected teardrop cracking in nickel based superalloys: sustained macroscopic deflected fatigue crack growth
Deflected teardrop cracking in nickel based superalloys: sustained macroscopic deflected fatigue crack growth
A sustained macroscopic deflected fatigue crack growth, the so-called ‘tear drop’ crack (TDC), has been observed under mode I (tensile) loading in Udimet 720Li when tested at 300°C in air and at 300, 600 and 650°C in vacuum. A definition of the onset of sustained shear crack growth is proposed and applied to different test geometries in different temperatures and environments. SEM analysis of the fracture surfaces have shown a competition between the sustained shear and mode I crack growth modes in both the terraced shear lip and flat tear drop region, which indicates that the macroscopic deflection is triggered by the free surface.
The tilt angles measured from the deflections have been used to define a mixed mode plane stress test, attempting to replicate the stress state giving rise to deflected shear growth.
nickel based superalloys, teardrop cracking, sustained deflected fatigue crack growth, mixed mode
188-201
Schoettle, C.
fc2bdbe4-b10a-42e0-b839-7985e6a9c622
Sinclair, I.
6005f6c1-f478-434e-a52d-d310c18ade0d
Starink, M.J.
fe61a323-4e0c-49c7-91f0-4450e1ec1e51
Reed, P.A.S.
8b79d87f-3288-4167-bcfc-c1de4b93ce17
November 2012
Schoettle, C.
fc2bdbe4-b10a-42e0-b839-7985e6a9c622
Sinclair, I.
6005f6c1-f478-434e-a52d-d310c18ade0d
Starink, M.J.
fe61a323-4e0c-49c7-91f0-4450e1ec1e51
Reed, P.A.S.
8b79d87f-3288-4167-bcfc-c1de4b93ce17
Schoettle, C., Sinclair, I., Starink, M.J. and Reed, P.A.S.
(2012)
Deflected teardrop cracking in nickel based superalloys: sustained macroscopic deflected fatigue crack growth.
International Journal of Fatigue, 44, .
(doi:10.1016/j.ijfatigue.2012.04.017).
Abstract
A sustained macroscopic deflected fatigue crack growth, the so-called ‘tear drop’ crack (TDC), has been observed under mode I (tensile) loading in Udimet 720Li when tested at 300°C in air and at 300, 600 and 650°C in vacuum. A definition of the onset of sustained shear crack growth is proposed and applied to different test geometries in different temperatures and environments. SEM analysis of the fracture surfaces have shown a competition between the sustained shear and mode I crack growth modes in both the terraced shear lip and flat tear drop region, which indicates that the macroscopic deflection is triggered by the free surface.
The tilt angles measured from the deflections have been used to define a mixed mode plane stress test, attempting to replicate the stress state giving rise to deflected shear growth.
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e-pub ahead of print date: 17 May 2012
Published date: November 2012
Keywords:
nickel based superalloys, teardrop cracking, sustained deflected fatigue crack growth, mixed mode
Organisations:
Engineering Mats & Surface Engineerg Gp
Identifiers
Local EPrints ID: 339007
URI: http://eprints.soton.ac.uk/id/eprint/339007
ISSN: 0142-1123
PURE UUID: f5d5e416-a188-4187-9ce2-d8b89fc3df47
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Date deposited: 21 May 2012 14:10
Last modified: 15 Mar 2024 02:45
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Author:
C. Schoettle
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