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The oxidation damage of Ni-based superalloy, RR1000, with different surface modifications and the role of oxidation in fatigue crack initiation

Cruchley, Sam (2015)
Ph.D. thesis, University of Birmingham.

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Abstract

The oxidation behaviour of RR1000 with different surface modifications has been well studied using detailed metallographic and mass gain measurements. The oxide comprises of an external chromia scale with isolated grains of TiO\(_2\) on the outer surface. Sub-surface internal alumina is present, beneath which the presence of TiN occurs (at higher temperatures >800\(^o\)C), all contained within a ɣ' denuded zone. The chromia external scale growth rate is significantly greater than pure chromia on chromium and the enhancement is attributed to the increased ionic transport caused by doping of the chromia layer with Ti. This effect is still seen regardless of surface condition prior to oxidation.

Oxides, especially internal intergranular oxides have been shown to crack under room temperature fatigue conditions, causing a significant fatigue life deficit at a maximum applied stress of 800 MPa and 1000 MPa. At 825 MPa, it is suggested that plastic yielding of the ɣ' denuded zone initiated leading to a substantial increase in fatigue life, through either blunting the crack by deforming to accommodate the stress concentration at the crack tip or by preventing cracking of the oxides.

Type of Work:Ph.D. thesis.
Supervisor(s):Evans, Hugh and Bowen, Paul
School/Faculty:Colleges (2008 onwards) > College of Engineering & Physical Sciences
Department:School of Metallurgy and Materials
Additional Information:

Embargo until: 31/12/2018.

Publications arising from research:

S. Cruchley, M.P. Taylor, H.E. Evans, P. Bowen, M.C. Hardy, and S. Stekovic, Microstructural Characterisation of High Temperature Oxidation of Nickel Base Superalloy
RR1000 and the Effect of Shot-Peening, in Superalloys 2012: 12th International Symposium on Superalloys, 2012, TMS: Seven Springs, PA. p. 751-758. http://dx.doi.10.1002/9781118516430.ch83.

S. Cruchley, M.P. Taylor, H.E. Evans, P. Bowen, M.C. Hardy, and S. Stekovic, Chromia
layer growth on a Ni-based superalloy: Sub-parabolic kinetics and the role of titanium, Corrosion Science, 2013. 75: p. 58-66. http://dx.doi.10.1016/j.corsci.2013.05.016.

S. Cruchley, M.P. Taylor, H.E. Evans, P. Bowen, J. Sumner, J.R. Nicholls, N.J. Simms, R.J. Chater, B. A. Shollock, B. Foss, M. C. Hardy and S. Stekovic, A Cautionary Note on the use of Focused Ion Beam (FIB) Sectioning as a Technique for Characterising Oxidation Damage in Ni-based Superalloys, Materials at High Temperatures, 2014. 31(1): p. 27-33. http://dx.doi.org/10.1179/0960340913Z.0000000004

S. Cruchley, M.P. Taylor, H.E. Evans, M.C. Hardy and D.J. Child, Characterisation of the sub-surface oxidation damage in Ni-based superalloy, RR1000, Materials Science and Technology, 2014. 30(15): p. 1884-1889. http://dx.doi.org/10.1179/1743284714Y.0000000541

S. Cruchley, M.P. Taylor, H.Y. Li, H.E. Evans, P. Bowen, M.C. Hardy and D.J. Child, Effect of prior oxidation on high cycle fatigue performance of RR1000 and the role of oxidation in fatigue crack initiation, Materials at High Temperature, 32(1-2): p. 68-73. http://dx.doi.org/10.1179/0960340914Z.00000000064.

Subjects:QD Chemistry
TN Mining engineering. Metallurgy
Institution:University of Birmingham
ID Code:5894
This unpublished thesis/dissertation is copyright of the author and/or third parties. The intellectual property rights of the author or third parties in respect of this work are as defined by The Copyright Designs and Patents Act 1988 or as modified by any successor legislation. Any use made of information contained in this thesis/dissertation must be in accordance with that legislation and must be properly acknowledged. Further distribution or reproduction in any format is prohibited without the permission of the copyright holder.
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