Oxidation and its Effect on the Fatigue Properties of the Nickel Based Superalloy RR1000

LEWIS, DAVID

doi:10.23889/SUthesis.58632

E-Thesis 437 views

Oxidation and its Effect on the Fatigue Properties of the Nickel Based Superalloy RR1000 / DAVID LEWIS

Swansea University Author: DAVID LEWIS

Redacted version - open access under embargo until: 29th July 2025

DOI (Published version): 10.23889/SUthesis.58632

Abstract

As temperatures within the aero engine increase, oxidation will begin to have a greater effect on the high temperature materials. How this damage will affect the mechanical properties of the high pressure turbine rotor material i.e. nickel superalloy RR1000, must be understood. In this study an atte...

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Published:	Swansea 2021
Institution:	Swansea University
Degree level:	Doctoral
Degree name:	EngD
Supervisor:	Whittaker, Mark T. ; Mignanelli, Paul M.
URI:	https://cronfa.swan.ac.uk/Record/cronfa58632
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first_indexed	2021-11-12T13:41:33Z
last_indexed	2021-11-13T04:25:41Z
id	cronfa58632
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spelling	2021-11-12T14:06:16.6435130 v2 58632 2021-11-12 Oxidation and its Effect on the Fatigue Properties of the Nickel Based Superalloy RR1000 58b118ff28c0039d4de2adfda854b71d DAVID LEWIS DAVID LEWIS true false 2021-11-12 As temperatures within the aero engine increase, oxidation will begin to have a greater effect on the high temperature materials. How this damage will affect the mechanical properties of the high pressure turbine rotor material i.e. nickel superalloy RR1000, must be understood. In this study an attempt was made to understand how the oxides form and the effect they will have on the fatigue performance of the alloy. Initial thermal exposures were undertaken under no-load and tensile and compressive loads in order to determine the variation in oxide characteristics. Subsequent thermal exposures were undertaken to determine the effect oxidation has on the fatigue lives of the nickel-based superalloy. The oxide morphologies were the same throughout, but the application of an external load caused increased reaction rates, with compressive loads causing greater rate increase than tensile. Methodologies were determined using forms of the Arrhenius relationship to numerically compare the oxidation reaction. Tensile and compressive oxidation asymmetry was believed to be related to the mechano-chemical nature of the reaction. The pre-fatigue thermal exposures initially caused a considerable reduction in the fatigue lives with increasing oxidation. However, the longest exposure time resulted in an S-N curve that lay between the shortest and mid length exposures. A range of analyses were undertaken to determine the presence of any relevant mechanisms that caused this unexpected life improvement. It was found that few of the mechanisms investigated were likely to have an effect on the change in life. The exceptions were; reduction in dislocation movement and crack deflection as a result of a recrystallised zone at the surface, changes in the tertiary γ’ size, variation in hardness of different regions due to a γ’ depleted plastic zone and a hard ceramic oxide, and reduced initiations due to the presence of a ‘healing’ chromium oxide scale. Notch fatigue tests were performed to determine the importance of the findings to components in service and it was found that the notch acted as the cause of crack initiation, effectively mitigating against the effects of the oxidation damage. E-Thesis Swansea Superalloy, oxidation, fatigue, microscopy, nano-indentation 12 11 2021 2021-11-12 10.23889/SUthesis.58632 A selection of third party content is redacted or is partially redacted from this thesis due to copyright restrictions. COLLEGE NANME COLLEGE CODE Swansea University Whittaker, Mark T. ; Mignanelli, Paul M. Doctoral EngD EPSRC doctoral training grant 2021-11-12T14:06:16.6435130 2021-11-12T13:37:42.3016128 Faculty of Science and Engineering School of Engineering and Applied Sciences - Uncategorised DAVID LEWIS 1 Under embargo Under embargo 2021-11-12T14:01:48.7776921 Output 14604184 application/pdf Redacted version - open access true 2025-07-29T00:00:00.0000000 Copyright: The author, David T.S. Lewis, 2020. true eng
title	Oxidation and its Effect on the Fatigue Properties of the Nickel Based Superalloy RR1000
spellingShingle	Oxidation and its Effect on the Fatigue Properties of the Nickel Based Superalloy RR1000 DAVID LEWIS
title_short	Oxidation and its Effect on the Fatigue Properties of the Nickel Based Superalloy RR1000
title_full	Oxidation and its Effect on the Fatigue Properties of the Nickel Based Superalloy RR1000
title_fullStr	Oxidation and its Effect on the Fatigue Properties of the Nickel Based Superalloy RR1000
title_full_unstemmed	Oxidation and its Effect on the Fatigue Properties of the Nickel Based Superalloy RR1000
title_sort	Oxidation and its Effect on the Fatigue Properties of the Nickel Based Superalloy RR1000
author_id_str_mv	58b118ff28c0039d4de2adfda854b71d
author_id_fullname_str_mv	58b118ff28c0039d4de2adfda854b71d_***_DAVID LEWIS
author	DAVID LEWIS
author2	DAVID LEWIS
format	E-Thesis
publishDate	2021
institution	Swansea University
doi_str_mv	10.23889/SUthesis.58632
college_str	Faculty of Science and Engineering
hierarchytype
hierarchy_top_id	facultyofscienceandengineering
hierarchy_top_title	Faculty of Science and Engineering
hierarchy_parent_id	facultyofscienceandengineering
hierarchy_parent_title	Faculty of Science and Engineering
department_str	School of Engineering and Applied Sciences - Uncategorised{{{_:::_}}}Faculty of Science and Engineering{{{_:::_}}}School of Engineering and Applied Sciences - Uncategorised
document_store_str	0
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description	As temperatures within the aero engine increase, oxidation will begin to have a greater effect on the high temperature materials. How this damage will affect the mechanical properties of the high pressure turbine rotor material i.e. nickel superalloy RR1000, must be understood. In this study an attempt was made to understand how the oxides form and the effect they will have on the fatigue performance of the alloy. Initial thermal exposures were undertaken under no-load and tensile and compressive loads in order to determine the variation in oxide characteristics. Subsequent thermal exposures were undertaken to determine the effect oxidation has on the fatigue lives of the nickel-based superalloy. The oxide morphologies were the same throughout, but the application of an external load caused increased reaction rates, with compressive loads causing greater rate increase than tensile. Methodologies were determined using forms of the Arrhenius relationship to numerically compare the oxidation reaction. Tensile and compressive oxidation asymmetry was believed to be related to the mechano-chemical nature of the reaction. The pre-fatigue thermal exposures initially caused a considerable reduction in the fatigue lives with increasing oxidation. However, the longest exposure time resulted in an S-N curve that lay between the shortest and mid length exposures. A range of analyses were undertaken to determine the presence of any relevant mechanisms that caused this unexpected life improvement. It was found that few of the mechanisms investigated were likely to have an effect on the change in life. The exceptions were; reduction in dislocation movement and crack deflection as a result of a recrystallised zone at the surface, changes in the tertiary γ’ size, variation in hardness of different regions due to a γ’ depleted plastic zone and a hard ceramic oxide, and reduced initiations due to the presence of a ‘healing’ chromium oxide scale. Notch fatigue tests were performed to determine the importance of the findings to components in service and it was found that the notch acted as the cause of crack initiation, effectively mitigating against the effects of the oxidation damage.
published_date	2021-11-12T04:15:18Z
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score	11.037603

Oxidation and its Effect on the Fatigue Properties of the Nickel Based Superalloy RR1000 / DAVID LEWIS

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