{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/34460"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/34460","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Thermo-mechanical response and plastic deformation behavior of Hastelloy X at elevated temperatures — role of dynamic strain aging","abstract":"In this work, the plastic behavior of Hastelloy X subjected to thermo-mechanical loading is investigated, and the phenomenon of dynamic strain aging is studied under isothermal and temperature jump experiments, using the technique of digital image correlation (DIC). The material of interest, a Ni-based superalloy, is widely used in high temperature applications, and it is important to understand its plastic response in such loading regimes. It is seen that Hastelloy X exhibits serrated or jerky flow behavior at higher temperatures, which manifests as oscillations on the uniaxial tension stress strain curve. This is a consequence of the Portevin-Le Chatelier (PLC) effect, and is characterized by strain bands propagating through the length of the specimen, at specific time intervals, leading to a local increase in strain as the band propagates. Although the existence of a PLC effect in Hastelloy X has been observed before, the current work elucidates the effect of PLC bands on the deformation under uniaxial and biaxial states of stress, and under both isothermal and thermal cycling conditions. Variability in the response at different temperatures is studied locally, through the DIC measurements, and globally through far field measurements, with a relation between the two measurement scales being established. The DIC results, when correlated with the global load-displacement measurements, illustrate the contribution of the PLC effect to the plastic response of the specimen. A section of experimental work is devoted to characterization of the material behavior, and understanding the phenomenon of dynamic strain aging. A qualitative assessment of PLC band characteristics is also discussed. The effects of dynamic strain aging on the reduction of flow stress are investigated under both uniaxial and biaxial loading conditions. Cyclic thermal experiments under the influence of stress concentrations lead to certain counterintuitive phenomena such as greater strain accumulation at lower flow stresses.","abstract_html":"In this work, the plastic behavior of Hastelloy X subjected to thermo-mechanical loading is investigated, and the phenomenon of dynamic strain aging is studied under isothermal and temperature jump experiments, using the technique of digital image correlation (DIC). The material of interest, a Ni-based superalloy, is widely used in high temperature applications, and it is important to understand its plastic response in such loading regimes. It is seen that Hastelloy X exhibits serrated or jerky flow behavior at higher temperatures, which manifests as oscillations on the uniaxial tension stress strain curve. This is a consequence of the Portevin-Le Chatelier (PLC) effect, and is characterized by strain bands propagating through the length of the specimen, at specific time intervals, leading to a local increase in strain as the band propagates. Although the existence of a PLC effect in Hastelloy X has been observed before, the current work elucidates the effect of PLC bands on the deformation under uniaxial and biaxial states of stress, and under both isothermal and thermal cycling conditions. Variability in the response at different temperatures is studied locally, through the DIC measurements, and globally through far field measurements, with a relation between the two measurement scales being established. The DIC results, when correlated with the global load-displacement measurements, illustrate the contribution of the PLC effect to the plastic response of the specimen. A section of experimental work is devoted to characterization of the material behavior, and understanding the phenomenon of dynamic strain aging. A qualitative assessment of PLC band characteristics is also discussed. The effects of dynamic strain aging on the reduction of flow stress are investigated under both uniaxial and biaxial loading conditions. Cyclic thermal experiments under the influence of stress concentrations lead to certain counterintuitive phenomena such as greater strain accumulation at lower flow stresses.","abstract_has_math":false,"creators":["Swaminathan, Bharath"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"M.S.","degree_level":"Thesis","degree_discipline":"Aerospace Engineering","degree_department":null,"school":null,"contributors":["Lambros, John"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2012,"date_issued":"2012-09-18T21:18:15Z","date_published":"2012-09-18T21:18:15Z","updated_at":"2026-07-22T22:25:31Z","subjects":["Dynamic Strain Aging","Portevin-Le Chatelier effect","Hastelloy X","Nickel based superalloys","Plasticity","Digital Image Correlation (DIC)","Stress Concentration","Cottrell-Stokes effect","strain jumps","Load relaxation","Thermo-mechanical loading","flow stress","high temperature digital image correlation (DIC)"],"languages":["en"],"rights":["Copyright 2012 by Bharath Swaminathan. All Rights Reserved."],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/2142/34460","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Lambros, John"]},{"key":"dc:creator","label":"Author","values":["Swaminathan, Bharath"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2012-09-18T21:18:15Z","2014-09-18T10:00:47Z","2012-08"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Aerospace Engineering"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Thesis"]},{"key":"thesis:degree_name","label":"Degree Name","values":["M.S."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois at Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Dynamic Strain Aging","Portevin-Le Chatelier effect","Hastelloy X","Nickel based superalloys","Plasticity","Digital Image Correlation (DIC)","Stress Concentration","Cottrell-Stokes effect","strain jumps","Load relaxation","Thermo-mechanical loading","flow stress","high temperature digital image correlation (DIC)"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2012 by Bharath Swaminathan. All Rights Reserved."]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/34460"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["In this work, the plastic behavior of Hastelloy X subjected to thermo-mechanical loading is investigated, and the phenomenon of dynamic strain aging is studied under isothermal and temperature jump experiments, using the technique of digital image correlation (DIC). The material of interest, a Ni-based superalloy, is widely used in high temperature applications, and it is important to understand its plastic response in such loading regimes. It is seen that Hastelloy X exhibits serrated or jerky flow behavior at higher temperatures, which manifests as oscillations on the uniaxial tension stress strain curve. This is a consequence of the Portevin-Le Chatelier (PLC) effect, and is characterized by strain bands propagating through the length of the specimen, at specific time intervals, leading to a local increase in strain as the band propagates. Although the existence of a PLC effect in Hastelloy X has been observed before, the current work elucidates the effect of PLC bands on the deformation under uniaxial and biaxial states of stress, and under both isothermal and thermal cycling conditions. Variability in the response at different temperatures is studied locally, through the DIC measurements, and globally through far field measurements, with a relation between the two measurement scales being established. The DIC results, when correlated with the global load-displacement measurements, illustrate the contribution of the PLC effect to the plastic response of the specimen. A section of experimental work is devoted to characterization of the material behavior, and understanding the phenomenon of dynamic strain aging. A qualitative assessment of PLC band characteristics is also discussed. The effects of dynamic strain aging on the reduction of flow stress are investigated under both uniaxial and biaxial loading conditions. Cyclic thermal experiments under the influence of stress concentrations lead to certain counterintuitive phenomena such as greater strain accumulation at lower flow stresses.","Item withdrawn by Mark Zulauf (zulauf@illinois.edu) on 2012-05-24T21:17:50Z Item was in collections: University of Illinois Theses & Dissertations (ID: 1) No. of bitstreams: 1 Swaminathan_Bharath.pdf: 26040071 bytes, checksum: 7750cdf28f694800919dea90c2d47aed (MD5)","Made available in DSpace on 2012-09-18T21:18:15Z (GMT). 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The material of interest, a Ni-based superalloy, is widely used in high temperature applications, and it is important to understand its plastic response in such loading regimes. It is seen that Hastelloy X exhibits serrated or jerky flow behavior at higher temperatures, which manifests as oscillations on the uniaxial tension stress strain curve. This is a consequence of the Portevin-Le Chatelier (PLC) effect, and is characterized by strain bands propagating through the length of the specimen, at specific time intervals, leading to a local increase in strain as the band propagates. Although the existence of a PLC effect in Hastelloy X has been observed before, the current work elucidates the effect of PLC bands on the deformation under uniaxial and biaxial states of stress, and under both isothermal and thermal cycling conditions. Variability in the response at different temperatures is studied locally, through the DIC measurements, and globally through far field measurements, with a relation between the two measurement scales being established. The DIC results, when correlated with the global load-displacement measurements, illustrate the contribution of the PLC effect to the plastic response of the specimen. A section of experimental work is devoted to characterization of the material behavior, and understanding the phenomenon of dynamic strain aging. A qualitative assessment of PLC band characteristics is also discussed. The effects of dynamic strain aging on the reduction of flow stress are investigated under both uniaxial and biaxial loading conditions. Cyclic thermal experiments under the influence of stress concentrations lead to certain counterintuitive phenomena such as greater strain accumulation at lower flow stresses.","Item withdrawn by Mark Zulauf (zulauf@illinois.edu) on 2012-05-24T21:17:50Z Item was in collections: University of Illinois Theses & Dissertations (ID: 1) No. of bitstreams: 1 Swaminathan_Bharath.pdf: 26040071 bytes, checksum: 7750cdf28f694800919dea90c2d47aed (MD5)","Made available in DSpace on 2012-09-18T21:18:15Z (GMT). No. of bitstreams: 2 Swaminathan_Bharath.pdf: 26040248 bytes, checksum: fed51125d7b2918db0319e25504808de (MD5) license.txt: 4069 bytes, checksum: 0d10c5246aa46cb2894afd2e3f61dd18 (MD5)","Restriction data tranferred 2014-07-01T11:35:02-05:00 Original Data Group with Access UIUC Users [automated] Release Date: 2014-09-18 16:21:01 UTC Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD system","Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Seth Robbins (srobbins@illinois.edu) on 2012-09-18T21:21:08Z Item is restricted until 2014-09-18T21:21:01Z","U of I Only Restriction Lifted for Item 34734 on 2014-09-18T10:00:47Z."],"dc:identifier":["http://hdl.handle.net/2142/34460"],"dc:language":["en"],"dc:rights":["Copyright 2012 by Bharath Swaminathan. All Rights Reserved."],"dc:subject":["Dynamic Strain Aging","Portevin-Le Chatelier effect","Hastelloy X","Nickel based superalloys","Plasticity","Digital Image Correlation (DIC)","Stress Concentration","Cottrell-Stokes effect","strain jumps","Load relaxation","Thermo-mechanical loading","flow stress","high temperature digital image correlation (DIC)"],"dc:title":["Thermo-mechanical response and plastic deformation behavior of Hastelloy X at elevated temperatures — role of dynamic strain aging"],"thesis:degree_discipline":["Aerospace Engineering"],"thesis:degree_level":["Thesis"],"thesis:degree_name":["M.S."],"thesis:institution_name":["University of Illinois at Urbana-Champaign"]},"updated_at":"2026-07-22T22:25:31Z"}