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The Effect of Salt Composition on the Stress-Free and Cyclic Corrosion Performance of a Nickel-Based Superalloy / MATHEW HENDERY

Swansea University Author: MATHEW HENDERY

  • Redacted version - open access under embargo until: 21st December 2026

DOI (Published version): 10.23889/SUthesis.59395

Abstract

The stress-free corrosion and corrosion fatigue of nickel-based superalloy fine-grain (FG) RR1000 with varying salt compositions has been studied to provide a mechanistic understanding of the hot corrosion damage taking place at exposure temperatures of 600℃, approximately 50℃ lower than that of the...

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Published: Swansea 2021
Institution: Swansea University
Degree level: Doctoral
Degree name: EngD
Supervisor: Whittaker, Mark T.
URI: https://cronfa.swan.ac.uk/Record/cronfa59395
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These temperatures are continually increasing, with the drive to improve power plant efficiencies. The operating temperature range and sulphur containing combustion gases and fuels leave the rotor and blade materials open to attack from hot corrosion. The traditional mechanisms of hot corrosion in gas turbines have been reviewed; type I, transitional, and type II hot corrosion. Additionally, a form of hot corrosion typically observed in fireside boilers (fireside hot corrosion) has been discussed due to the satisfaction of many of the morphology requirements in this study. Characterisation of the differences between type II hot corrosion under stress-free conditions at 600&#x2103; and 700&#x2103; for equivalent salt fluxes, highlighted sulphide particle ingress into the bulk material underneath pits at 600&#x2103;, which has only recently been observed at 700&#x2103; in relatively recent work. Potassium-based salts were identified as the most damaging at 600&#x2103;, compared to the 98%Na2SO4-2%NaCl typically used in hot corrosion studies at 700&#x2103;. Additional testing attempted to identify the influence of potassium versus sodium based salts and their relative sulphate/chloride proportions. Corrosion-fatigue testing identified an unusual threshold stress, above which salts with higher chlorine were more damaging. This is thought to be due to the higher stresses promoting oxide cracking, thus allowing ingress of chlorine to reduce fatigue initiation lives. Below this threshold stress the relative quantity of sulphate appeared controlling, with electron back-scattered diffraction (EBSD) and pit measurement techniques showing pitting damage being necessary to penetrate the strain hardened layer (SHL) in order to promote crack growth.</abstract><type>E-Thesis</type><journal/><volume/><journalNumber/><paginationStart/><paginationEnd/><publisher/><placeOfPublication>Swansea</placeOfPublication><isbnPrint/><isbnElectronic/><issnPrint/><issnElectronic/><keywords>Molten salts, nickel, superalloys, corrosion fatigue, sulphidation</keywords><publishedDay>21</publishedDay><publishedMonth>12</publishedMonth><publishedYear>2021</publishedYear><publishedDate>2021-12-21</publishedDate><doi>10.23889/SUthesis.59395</doi><url/><notes>A selection of third party content is redacted or is partially redacted from this thesis due to copyright restrictions.ORCiD identifier: https://orcid.org/0000-0001-7279-3175</notes><college>COLLEGE NANME</college><CollegeCode>COLLEGE CODE</CollegeCode><institution>Swansea University</institution><supervisor>Whittaker, Mark T.</supervisor><degreelevel>Doctoral</degreelevel><degreename>EngD</degreename><degreesponsorsfunders>The current research was funded by the EPSRC Rolls-Royce Strategic Partnership in Structural Metallic Systems for Gas Turbines (grants EP/H500383/1 and EP/H022309/1) alongside the Materials and Manufacturing Academy (M2A) supported through the European Social Fund. The provision of materials and supporting information from Rolls-Royce plc is gratefully acknowledged</degreesponsorsfunders><apcterm/><lastEdited>2022-02-14T14:09:06.7693192</lastEdited><Created>2022-02-14T12:06:57.6193296</Created><path><level id="1">Faculty of Science and Engineering</level><level id="2">School of Engineering and Applied Sciences - Uncategorised</level></path><authors><author><firstname>MATHEW</firstname><surname>HENDERY</surname><order>1</order></author></authors><documents><document><filename>Under embargo</filename><originalFilename>Under embargo</originalFilename><uploaded>2022-02-14T12:25:42.7632378</uploaded><type>Output</type><contentLength>8071812</contentLength><contentType>application/pdf</contentType><version>Redacted version - open access</version><cronfaStatus>true</cronfaStatus><embargoDate>2026-12-21T00:00:00.0000000</embargoDate><documentNotes>The Effect of Salt Composition on the Stress-Free and Cyclic Corrosion Performance of a Nickel- Based Superalloy &#xA9; 2021 by Mathew L. 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spelling 2022-02-14T14:09:06.7693192 v2 59395 2022-02-14 The Effect of Salt Composition on the Stress-Free and Cyclic Corrosion Performance of a Nickel-Based Superalloy 3800acf7e6c0ed6c87028454fae97d2f MATHEW HENDERY MATHEW HENDERY true false 2022-02-14 The stress-free corrosion and corrosion fatigue of nickel-based superalloy fine-grain (FG) RR1000 with varying salt compositions has been studied to provide a mechanistic understanding of the hot corrosion damage taking place at exposure temperatures of 600℃, approximately 50℃ lower than that of the current literature. Gas turbine rotors typically experience lower tempeatures than the blades to which they are attached. These temperatures are continually increasing, with the drive to improve power plant efficiencies. The operating temperature range and sulphur containing combustion gases and fuels leave the rotor and blade materials open to attack from hot corrosion. The traditional mechanisms of hot corrosion in gas turbines have been reviewed; type I, transitional, and type II hot corrosion. Additionally, a form of hot corrosion typically observed in fireside boilers (fireside hot corrosion) has been discussed due to the satisfaction of many of the morphology requirements in this study. Characterisation of the differences between type II hot corrosion under stress-free conditions at 600℃ and 700℃ for equivalent salt fluxes, highlighted sulphide particle ingress into the bulk material underneath pits at 600℃, which has only recently been observed at 700℃ in relatively recent work. Potassium-based salts were identified as the most damaging at 600℃, compared to the 98%Na2SO4-2%NaCl typically used in hot corrosion studies at 700℃. Additional testing attempted to identify the influence of potassium versus sodium based salts and their relative sulphate/chloride proportions. Corrosion-fatigue testing identified an unusual threshold stress, above which salts with higher chlorine were more damaging. This is thought to be due to the higher stresses promoting oxide cracking, thus allowing ingress of chlorine to reduce fatigue initiation lives. Below this threshold stress the relative quantity of sulphate appeared controlling, with electron back-scattered diffraction (EBSD) and pit measurement techniques showing pitting damage being necessary to penetrate the strain hardened layer (SHL) in order to promote crack growth. E-Thesis Swansea Molten salts, nickel, superalloys, corrosion fatigue, sulphidation 21 12 2021 2021-12-21 10.23889/SUthesis.59395 A selection of third party content is redacted or is partially redacted from this thesis due to copyright restrictions.ORCiD identifier: https://orcid.org/0000-0001-7279-3175 COLLEGE NANME COLLEGE CODE Swansea University Whittaker, Mark T. Doctoral EngD The current research was funded by the EPSRC Rolls-Royce Strategic Partnership in Structural Metallic Systems for Gas Turbines (grants EP/H500383/1 and EP/H022309/1) alongside the Materials and Manufacturing Academy (M2A) supported through the European Social Fund. The provision of materials and supporting information from Rolls-Royce plc is gratefully acknowledged 2022-02-14T14:09:06.7693192 2022-02-14T12:06:57.6193296 Faculty of Science and Engineering School of Engineering and Applied Sciences - Uncategorised MATHEW HENDERY 1 Under embargo Under embargo 2022-02-14T12:25:42.7632378 Output 8071812 application/pdf Redacted version - open access true 2026-12-21T00:00:00.0000000 The Effect of Salt Composition on the Stress-Free and Cyclic Corrosion Performance of a Nickel- Based Superalloy © 2021 by Mathew L. Hendery is licensed under a CC BY-NC-ND 4.0 License. true eng https://creativecommons.org/licenses/by-nc-nd/4.0/
title The Effect of Salt Composition on the Stress-Free and Cyclic Corrosion Performance of a Nickel-Based Superalloy
spellingShingle The Effect of Salt Composition on the Stress-Free and Cyclic Corrosion Performance of a Nickel-Based Superalloy
MATHEW HENDERY
title_short The Effect of Salt Composition on the Stress-Free and Cyclic Corrosion Performance of a Nickel-Based Superalloy
title_full The Effect of Salt Composition on the Stress-Free and Cyclic Corrosion Performance of a Nickel-Based Superalloy
title_fullStr The Effect of Salt Composition on the Stress-Free and Cyclic Corrosion Performance of a Nickel-Based Superalloy
title_full_unstemmed The Effect of Salt Composition on the Stress-Free and Cyclic Corrosion Performance of a Nickel-Based Superalloy
title_sort The Effect of Salt Composition on the Stress-Free and Cyclic Corrosion Performance of a Nickel-Based Superalloy
author_id_str_mv 3800acf7e6c0ed6c87028454fae97d2f
author_id_fullname_str_mv 3800acf7e6c0ed6c87028454fae97d2f_***_MATHEW HENDERY
author MATHEW HENDERY
author2 MATHEW HENDERY
format E-Thesis
publishDate 2021
institution Swansea University
doi_str_mv 10.23889/SUthesis.59395
college_str Faculty of Science and Engineering
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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 The stress-free corrosion and corrosion fatigue of nickel-based superalloy fine-grain (FG) RR1000 with varying salt compositions has been studied to provide a mechanistic understanding of the hot corrosion damage taking place at exposure temperatures of 600℃, approximately 50℃ lower than that of the current literature. Gas turbine rotors typically experience lower tempeatures than the blades to which they are attached. These temperatures are continually increasing, with the drive to improve power plant efficiencies. The operating temperature range and sulphur containing combustion gases and fuels leave the rotor and blade materials open to attack from hot corrosion. The traditional mechanisms of hot corrosion in gas turbines have been reviewed; type I, transitional, and type II hot corrosion. Additionally, a form of hot corrosion typically observed in fireside boilers (fireside hot corrosion) has been discussed due to the satisfaction of many of the morphology requirements in this study. Characterisation of the differences between type II hot corrosion under stress-free conditions at 600℃ and 700℃ for equivalent salt fluxes, highlighted sulphide particle ingress into the bulk material underneath pits at 600℃, which has only recently been observed at 700℃ in relatively recent work. Potassium-based salts were identified as the most damaging at 600℃, compared to the 98%Na2SO4-2%NaCl typically used in hot corrosion studies at 700℃. Additional testing attempted to identify the influence of potassium versus sodium based salts and their relative sulphate/chloride proportions. Corrosion-fatigue testing identified an unusual threshold stress, above which salts with higher chlorine were more damaging. This is thought to be due to the higher stresses promoting oxide cracking, thus allowing ingress of chlorine to reduce fatigue initiation lives. Below this threshold stress the relative quantity of sulphate appeared controlling, with electron back-scattered diffraction (EBSD) and pit measurement techniques showing pitting damage being necessary to penetrate the strain hardened layer (SHL) in order to promote crack growth.
published_date 2021-12-21T04:16:40Z
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score 11.016235

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