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Thermo-Mechanical Fatigue Crack Growth of RR1000

Non-isothermal conditions during flight cycles have long led to the requirement for thermo-mechanical fatigue (TMF) evaluation of aerospace materials. However, the increased temperatures within the gas turbine engine have meant that the requirements for TMF testing now extend to disc alloys along wi...

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Autores principales: Pretty, Christopher John, Whitaker, Mark Thomas, Williams, Steve John
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5344579/
https://www.ncbi.nlm.nih.gov/pubmed/28772394
http://dx.doi.org/10.3390/ma10010034
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author Pretty, Christopher John
Whitaker, Mark Thomas
Williams, Steve John
author_facet Pretty, Christopher John
Whitaker, Mark Thomas
Williams, Steve John
author_sort Pretty, Christopher John
collection PubMed
description Non-isothermal conditions during flight cycles have long led to the requirement for thermo-mechanical fatigue (TMF) evaluation of aerospace materials. However, the increased temperatures within the gas turbine engine have meant that the requirements for TMF testing now extend to disc alloys along with blade materials. As such, fatigue crack growth rates are required to be evaluated under non-isothermal conditions along with the development of a detailed understanding of related failure mechanisms. In the current work, a TMF crack growth testing method has been developed utilising induction heating and direct current potential drop techniques for polycrystalline nickel-based superalloys, such as RR1000. Results have shown that in-phase (IP) testing produces accelerated crack growth rates compared with out-of-phase (OOP) due to increased temperature at peak stress and therefore increased time dependent crack growth. The ordering of the crack growth rates is supported by detailed fractographic analysis which shows intergranular crack growth in IP test specimens, and transgranular crack growth in 90° OOP and 180° OOP tests. Isothermal tests have also been carried out for comparison of crack growth rates at the point of peak stress in the TMF cycles.
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spelling pubmed-53445792017-07-28 Thermo-Mechanical Fatigue Crack Growth of RR1000 Pretty, Christopher John Whitaker, Mark Thomas Williams, Steve John Materials (Basel) Article Non-isothermal conditions during flight cycles have long led to the requirement for thermo-mechanical fatigue (TMF) evaluation of aerospace materials. However, the increased temperatures within the gas turbine engine have meant that the requirements for TMF testing now extend to disc alloys along with blade materials. As such, fatigue crack growth rates are required to be evaluated under non-isothermal conditions along with the development of a detailed understanding of related failure mechanisms. In the current work, a TMF crack growth testing method has been developed utilising induction heating and direct current potential drop techniques for polycrystalline nickel-based superalloys, such as RR1000. Results have shown that in-phase (IP) testing produces accelerated crack growth rates compared with out-of-phase (OOP) due to increased temperature at peak stress and therefore increased time dependent crack growth. The ordering of the crack growth rates is supported by detailed fractographic analysis which shows intergranular crack growth in IP test specimens, and transgranular crack growth in 90° OOP and 180° OOP tests. Isothermal tests have also been carried out for comparison of crack growth rates at the point of peak stress in the TMF cycles. MDPI 2017-01-04 /pmc/articles/PMC5344579/ /pubmed/28772394 http://dx.doi.org/10.3390/ma10010034 Text en © 2017 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC-BY) license (http://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Pretty, Christopher John
Whitaker, Mark Thomas
Williams, Steve John
Thermo-Mechanical Fatigue Crack Growth of RR1000
title Thermo-Mechanical Fatigue Crack Growth of RR1000
title_full Thermo-Mechanical Fatigue Crack Growth of RR1000
title_fullStr Thermo-Mechanical Fatigue Crack Growth of RR1000
title_full_unstemmed Thermo-Mechanical Fatigue Crack Growth of RR1000
title_short Thermo-Mechanical Fatigue Crack Growth of RR1000
title_sort thermo-mechanical fatigue crack growth of rr1000
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5344579/
https://www.ncbi.nlm.nih.gov/pubmed/28772394
http://dx.doi.org/10.3390/ma10010034
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