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The effects of microstructure and microtexture generated during solidification on deformation micromechanism in IN713C nickel-based superalloy / Gang Liu

DOI (Published version): 10.23889/Suthesis.53058

Abstract

Nickel-based superalloy IN713C produced by investment casting method are used for turbine blade of turbocharger in modern vehicles. IN713C alloy possesses good strength, fatigue, creep and high temperature oxidation resistance that make the alloy suitable to be used in harsh service environment such...

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Published: Swansea 2019
Institution: Swansea University
Degree level: Doctoral
Degree name: Ph.D
Supervisor: Birosca, Soran
URI: https://cronfa.swan.ac.uk/Record/cronfa53058
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first_indexed 2019-12-19T04:17:34Z
last_indexed 2020-09-17T03:16:08Z
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fullrecord <?xml version="1.0"?><rfc1807><datestamp>2019-12-18T17:26:31.6393572</datestamp><bib-version>v2</bib-version><id>53058</id><entry>2019-12-18</entry><title>The effects of microstructure and microtexture generated during solidification on deformation micromechanism in IN713C nickel-based superalloy</title><swanseaauthors/><date>2019-12-18</date><abstract>Nickel-based superalloy IN713C produced by investment casting method are used for turbine blade of turbocharger in modern vehicles. IN713C alloy possesses good strength, fatigue, creep and high temperature oxidation resistance that make the alloy suitable to be used in harsh service environment such as in the heating part of turbocharger. However, this material suffers from microstructure and microtexture heterogeneity produced during solidification. This microstructure heterogeneity across the component will inevitably give rise to local stress and strain accumulation which may facilitate crack initiation and affect crack propagation. Fatigue, both LCF (Low Cycle Fatigue) and HCF (High Cycle fatigue) are the common failure modes of turbine blade component in turbocharger. It is of industrial and academic interests to identify and classify the features of fracture surface of each failure mode. The necessity of optimisation of fatigue property for the newly developed turbocharger component parts is becoming critical and a fundamental research for understanding fatigue deformation micromechanism and the influence of microstructure (dendrite structure, carbides / oxidised carbides, grain size, etc.) and microtexture (individual crystallographic orientation, cluster of grains, etc.) is required. In the current investigation, LCF and HCF fatigue tests are conducted on real turbine blades as wel as on bars produced via investment casting. Various microstructure characterisation tools were used to identify the deformation micromechanics during LCF and HCF fatigue conditions. The results showed that in real turbine blades where there are much less casting defects than in the testing bar, the fatigue crack initiated from blade surface and crack propagation process was mainly dominated by oxidation-assistant process with oxidised carbides during LCF test. During the late stage of crack propagation, the interdendrite area was found to deform differently from the surrounding area to accommodate accumulated strain heterogeneity. Whilst for HCF, facet was initiated from slip planes with the highest Schmid factor and assisted by small porosity in most cases. As for the fatigue tests conducted on test bars produced via investment casting, the dendrite structure played a vital role in crack propagation mechanism. Based on the observations throughout this study, a concept of &#x2018;crack propagation unit (CPU)&#x2019; was proposed. From this proposed micro deformation mechanism, a new perspective of Hall-Patch effect of small grain size in casting alloys (containing dendrite structure) was further elucidated duirng both LCF and HCF. Finally, solidification trials were performed to study the exact correlation between solidification cooling rate and microstructure evolution including grain size and structure, gamma prime, carbides and other phases.</abstract><type>E-Thesis</type><journal/><publisher/><placeOfPublication>Swansea</placeOfPublication><keywords>Superalloy, deformation micromechanism, microstructure, microtexture</keywords><publishedDay>31</publishedDay><publishedMonth>10</publishedMonth><publishedYear>2019</publishedYear><publishedDate>2019-10-31</publishedDate><doi>10.23889/Suthesis.53058</doi><url/><notes>A selection of third party content is redacted or is partially redacted from this thesis.</notes><college>COLLEGE NANME</college><CollegeCode>COLLEGE CODE</CollegeCode><institution>Swansea University</institution><supervisor>Birosca, Soran</supervisor><degreelevel>Doctoral</degreelevel><degreename>Ph.D</degreename><apcterm/><lastEdited>2019-12-18T17:26:31.6393572</lastEdited><Created>2019-12-18T17:26:31.6393572</Created><authors><author><firstname>Gang</firstname><surname>Liu</surname><order>1</order></author></authors><documents><document><filename>53058__16143__64eeaea5a4ea42cfb6cfa6579b52130d.pdf</filename><originalFilename>Liu_Gang_PhD_Thesis_Final_Redacted.pdf</originalFilename><uploaded>2019-12-18T18:11:14.6783826</uploaded><type>Output</type><contentLength>27497883</contentLength><contentType>application/pdf</contentType><version>Redacted version - open access</version><cronfaStatus>true</cronfaStatus><copyrightCorrect>true</copyrightCorrect></document></documents><OutputDurs/></rfc1807>
spelling 2019-12-18T17:26:31.6393572 v2 53058 2019-12-18 The effects of microstructure and microtexture generated during solidification on deformation micromechanism in IN713C nickel-based superalloy 2019-12-18 Nickel-based superalloy IN713C produced by investment casting method are used for turbine blade of turbocharger in modern vehicles. IN713C alloy possesses good strength, fatigue, creep and high temperature oxidation resistance that make the alloy suitable to be used in harsh service environment such as in the heating part of turbocharger. However, this material suffers from microstructure and microtexture heterogeneity produced during solidification. This microstructure heterogeneity across the component will inevitably give rise to local stress and strain accumulation which may facilitate crack initiation and affect crack propagation. Fatigue, both LCF (Low Cycle Fatigue) and HCF (High Cycle fatigue) are the common failure modes of turbine blade component in turbocharger. It is of industrial and academic interests to identify and classify the features of fracture surface of each failure mode. The necessity of optimisation of fatigue property for the newly developed turbocharger component parts is becoming critical and a fundamental research for understanding fatigue deformation micromechanism and the influence of microstructure (dendrite structure, carbides / oxidised carbides, grain size, etc.) and microtexture (individual crystallographic orientation, cluster of grains, etc.) is required. In the current investigation, LCF and HCF fatigue tests are conducted on real turbine blades as wel as on bars produced via investment casting. Various microstructure characterisation tools were used to identify the deformation micromechanics during LCF and HCF fatigue conditions. The results showed that in real turbine blades where there are much less casting defects than in the testing bar, the fatigue crack initiated from blade surface and crack propagation process was mainly dominated by oxidation-assistant process with oxidised carbides during LCF test. During the late stage of crack propagation, the interdendrite area was found to deform differently from the surrounding area to accommodate accumulated strain heterogeneity. Whilst for HCF, facet was initiated from slip planes with the highest Schmid factor and assisted by small porosity in most cases. As for the fatigue tests conducted on test bars produced via investment casting, the dendrite structure played a vital role in crack propagation mechanism. Based on the observations throughout this study, a concept of ‘crack propagation unit (CPU)’ was proposed. From this proposed micro deformation mechanism, a new perspective of Hall-Patch effect of small grain size in casting alloys (containing dendrite structure) was further elucidated duirng both LCF and HCF. Finally, solidification trials were performed to study the exact correlation between solidification cooling rate and microstructure evolution including grain size and structure, gamma prime, carbides and other phases. E-Thesis Swansea Superalloy, deformation micromechanism, microstructure, microtexture 31 10 2019 2019-10-31 10.23889/Suthesis.53058 A selection of third party content is redacted or is partially redacted from this thesis. COLLEGE NANME COLLEGE CODE Swansea University Birosca, Soran Doctoral Ph.D 2019-12-18T17:26:31.6393572 2019-12-18T17:26:31.6393572 Gang Liu 1 53058__16143__64eeaea5a4ea42cfb6cfa6579b52130d.pdf Liu_Gang_PhD_Thesis_Final_Redacted.pdf 2019-12-18T18:11:14.6783826 Output 27497883 application/pdf Redacted version - open access true true
title The effects of microstructure and microtexture generated during solidification on deformation micromechanism in IN713C nickel-based superalloy
spellingShingle The effects of microstructure and microtexture generated during solidification on deformation micromechanism in IN713C nickel-based superalloy
,
title_short The effects of microstructure and microtexture generated during solidification on deformation micromechanism in IN713C nickel-based superalloy
title_full The effects of microstructure and microtexture generated during solidification on deformation micromechanism in IN713C nickel-based superalloy
title_fullStr The effects of microstructure and microtexture generated during solidification on deformation micromechanism in IN713C nickel-based superalloy
title_full_unstemmed The effects of microstructure and microtexture generated during solidification on deformation micromechanism in IN713C nickel-based superalloy
title_sort The effects of microstructure and microtexture generated during solidification on deformation micromechanism in IN713C nickel-based superalloy
author ,
author2 Gang Liu
format E-Thesis
publishDate 2019
institution Swansea University
doi_str_mv 10.23889/Suthesis.53058
document_store_str 1
active_str 0
description Nickel-based superalloy IN713C produced by investment casting method are used for turbine blade of turbocharger in modern vehicles. IN713C alloy possesses good strength, fatigue, creep and high temperature oxidation resistance that make the alloy suitable to be used in harsh service environment such as in the heating part of turbocharger. However, this material suffers from microstructure and microtexture heterogeneity produced during solidification. This microstructure heterogeneity across the component will inevitably give rise to local stress and strain accumulation which may facilitate crack initiation and affect crack propagation. Fatigue, both LCF (Low Cycle Fatigue) and HCF (High Cycle fatigue) are the common failure modes of turbine blade component in turbocharger. It is of industrial and academic interests to identify and classify the features of fracture surface of each failure mode. The necessity of optimisation of fatigue property for the newly developed turbocharger component parts is becoming critical and a fundamental research for understanding fatigue deformation micromechanism and the influence of microstructure (dendrite structure, carbides / oxidised carbides, grain size, etc.) and microtexture (individual crystallographic orientation, cluster of grains, etc.) is required. In the current investigation, LCF and HCF fatigue tests are conducted on real turbine blades as wel as on bars produced via investment casting. Various microstructure characterisation tools were used to identify the deformation micromechanics during LCF and HCF fatigue conditions. The results showed that in real turbine blades where there are much less casting defects than in the testing bar, the fatigue crack initiated from blade surface and crack propagation process was mainly dominated by oxidation-assistant process with oxidised carbides during LCF test. During the late stage of crack propagation, the interdendrite area was found to deform differently from the surrounding area to accommodate accumulated strain heterogeneity. Whilst for HCF, facet was initiated from slip planes with the highest Schmid factor and assisted by small porosity in most cases. As for the fatigue tests conducted on test bars produced via investment casting, the dendrite structure played a vital role in crack propagation mechanism. Based on the observations throughout this study, a concept of ‘crack propagation unit (CPU)’ was proposed. From this proposed micro deformation mechanism, a new perspective of Hall-Patch effect of small grain size in casting alloys (containing dendrite structure) was further elucidated duirng both LCF and HCF. Finally, solidification trials were performed to study the exact correlation between solidification cooling rate and microstructure evolution including grain size and structure, gamma prime, carbides and other phases.
published_date 2019-10-31T04:05:50Z
_version_ 1763753433769181184
score 11.036334

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