Estudo da resistência à corrosão intergranular do aço inoxidável austenítico f138 - perspectiva de desempenho após Deformação Plástica Severa (DPS)
Autor(a) principal: | |
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Data de Publicação: | 2018 |
Tipo de documento: | Dissertação |
Idioma: | por |
Título da fonte: | Repositório Institucional da UFSCAR |
Texto Completo: | https://repositorio.ufscar.br/handle/ufscar/10893 |
Resumo: | Austenitic stainless steels are widely used in heating and cooling circuits of thermoelectric and nuclear power plants (NPP) in the storage and reprocessing of nuclear fuels, mainly because they have good processability, high resistance to corrosion and creep. In particular in thermonuclear applications there is, however, the trouble of swelling caused by the nucleation of He voids and bubbles within the irradiated material and the increased sensitivity to intergranular corrosion due to the acceleration by diffusion of alloying elements in the material. Using severe plastic deformation (DPS) by the equal channel angular pressing (ECAP), an increase in the bondary area can be achieved as well as an increase in the density of dislocation enhancing He trapping in these regions. In relation to intergranular corrosion, the mechanism acting in most cases is the sensitization caused by precipitation in boundary grain of chromium-rich phases such as Cr23C6 and intermetallic precipitates. Increased plastic deformation (above 15%) can accelerate the sensitization process in austenitic stainless steels. In order to evaluate the effect of DPS on the corrosion resistance in oxidizing media, the ASTM 262 Practice C test was performed on a ASTM F138 steel after solubilization (1h at 1100oC), sensitization (240h at 850oC) and ECAP (7 passes at 300oC). Microstructural characterization was performed to analyze the sensitization process and to verify the corrosion mechanisms using Optical Microscopy (OM), Scanning Electron Microscopy (SEM) together with X-ray Energy Dispersion Spectroscopy (EDS), Transmission Electron Microscopy (TEM), Mapping of crystallographic orientation by diffraction patterns in MET, X-ray Diffraction (DR-X) and X-ray Excited Photoelectron Spectroscopy (XPS). It was verified that while the sensitized material underwent intergranular corrosion the solubilized and ECAP material were subjected to gerenal corrosion. The mass loss in HNO3 was larger for general corrosion than for intergranular corrosion. The passive film of the ECAP sample contained more Chromium III and Molybdenum than in the solubilized sample, and therefore presented higher resistance to corrosion in the HNO3 medium. The sensitized material presented precipitates with high concentration of chromium and molybdenum leaving the surrounding regions more susceptible to intergranular corrosion and by pites. The film formed on the surface of the sensitized samples presented higher amount of the Chromium VI oxide in relation to the solubilized samples and ECA7x. This oxide is less resistant to acid corrosion than Chromium III oxide. The passive film of the ECAP sample contained more Chromium III and Molybdenum than in the solubilized sample, and therefore presented higher resistance to corrosion in the HNO3 medium. |
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Rodrigues, Rodolfo de SouzaKliauga, Andrea Madeirahttp://lattes.cnpq.br/3527528295399928http://lattes.cnpq.br/27603878135353328568c7c8-672b-4fea-87a9-7ebee811892c2019-02-04T11:41:30Z2019-02-04T11:41:30Z2018-10-26RODRIGUES, Rodolfo de Souza. Estudo da resistência à corrosão intergranular do aço inoxidável austenítico f138 - perspectiva de desempenho após Deformação Plástica Severa (DPS). 2018. Dissertação (Mestrado em Ciência dos Materiais) – Universidade Federal de São Carlos, Sorocaba, 2018. Disponível em: https://repositorio.ufscar.br/handle/ufscar/10893.https://repositorio.ufscar.br/handle/ufscar/10893Austenitic stainless steels are widely used in heating and cooling circuits of thermoelectric and nuclear power plants (NPP) in the storage and reprocessing of nuclear fuels, mainly because they have good processability, high resistance to corrosion and creep. In particular in thermonuclear applications there is, however, the trouble of swelling caused by the nucleation of He voids and bubbles within the irradiated material and the increased sensitivity to intergranular corrosion due to the acceleration by diffusion of alloying elements in the material. Using severe plastic deformation (DPS) by the equal channel angular pressing (ECAP), an increase in the bondary area can be achieved as well as an increase in the density of dislocation enhancing He trapping in these regions. In relation to intergranular corrosion, the mechanism acting in most cases is the sensitization caused by precipitation in boundary grain of chromium-rich phases such as Cr23C6 and intermetallic precipitates. Increased plastic deformation (above 15%) can accelerate the sensitization process in austenitic stainless steels. In order to evaluate the effect of DPS on the corrosion resistance in oxidizing media, the ASTM 262 Practice C test was performed on a ASTM F138 steel after solubilization (1h at 1100oC), sensitization (240h at 850oC) and ECAP (7 passes at 300oC). Microstructural characterization was performed to analyze the sensitization process and to verify the corrosion mechanisms using Optical Microscopy (OM), Scanning Electron Microscopy (SEM) together with X-ray Energy Dispersion Spectroscopy (EDS), Transmission Electron Microscopy (TEM), Mapping of crystallographic orientation by diffraction patterns in MET, X-ray Diffraction (DR-X) and X-ray Excited Photoelectron Spectroscopy (XPS). It was verified that while the sensitized material underwent intergranular corrosion the solubilized and ECAP material were subjected to gerenal corrosion. The mass loss in HNO3 was larger for general corrosion than for intergranular corrosion. The passive film of the ECAP sample contained more Chromium III and Molybdenum than in the solubilized sample, and therefore presented higher resistance to corrosion in the HNO3 medium. The sensitized material presented precipitates with high concentration of chromium and molybdenum leaving the surrounding regions more susceptible to intergranular corrosion and by pites. The film formed on the surface of the sensitized samples presented higher amount of the Chromium VI oxide in relation to the solubilized samples and ECA7x. This oxide is less resistant to acid corrosion than Chromium III oxide. The passive film of the ECAP sample contained more Chromium III and Molybdenum than in the solubilized sample, and therefore presented higher resistance to corrosion in the HNO3 medium.Aços inoxidáveis austeníticos são amplamente empregados em estruturas dos circuitos de aquecimento e resfriamento de usinas termoelétricas, termonucleares, no armazenamento e reprocessamento de combustíveis nucleares, principalmente por apresentar boa processabilidade, alta resistência à corrosão e à fluência. Em particular, nas aplicações termonucleares, há, no entanto, a desvantagem do inchamento causado pela nucleação de voids e bolhas de He no interior do material irradiado e do aumento da sensibilidade à corrosão intergranular devido à aceleração do processo difusivo de elementos de liga no material. Utilizando deformação plástica severa (DPS), por meio do processo de extrusão por canal angular (ECA), consegue-se obter um aumento da área de contorno, assim como aumento da densidade de discordâncias, aprisionando os átomos de He nessas regiões. Em relação a corrosão intergranular, o mecanismo atuante na maioria dos casos é a sensitização causada por precipitação nos contornos de grão de fases ricas em cromo, tais como Cr23C6 e precipitados intermetálicos. O aumento de deformação plástica (acima de 15%) pode acelerar o processo de sensitização nos aços inoxidáveis austeníticos. Para avaliar esses efeitos de degradação de materiais metálicos nanoestruturados, foram realizados ensaios de corrosão em amostras de aço inoxidável austenítico ASTM F138 com granulação nanométrica, comparando as taxas de corrosão do mesmo aço em amostras após o processo de solubilização e sensitização. Para obter as amostras nanoestruturadas foi realizada a extrusão em canal angular (ECA) a, 300∘C, até uma deformação equivalente a 4,9. As amostras solubilizadas foram obtidas após permanecerem por 1100∘C a 1 hora em uma mufla e resfriadas em água. As amostras sensitizadas foram obtidas após permanecerem no forno a 850∘C durante 240 horas e resfriadas a temperatura ambiente. Os ensaios de corrosão foram realizados conforme a norma ASTM 262 Práticas A e C. Foram realizadas caracterizações microestruturais para análise do processo de sensitização e para verificar os mecanismos de corrosão utilizou-se Microscopia Óptica (MO), Microscopia Eletrônica de Varredura (MEV) juntamente com Espectroscopia por Dispersão de Energia de Raios-X (EDS), Microscopia Eletrônica de Transmissão (MET), Mapeamento da orientação cristalográfica por padrões de difração em MET, Difração de Raios-X (DR-X) e Espectroscopia de Fotoelétrons Excitados por Raios-X (XPS). Foi verificado que as amostras nanoestruturadas e sensitizadas apresentaram maior resistência a corrosão do que as amostras apenas solubilizadas. Na amostra sensitizada, a corrosão intergranular foi causada por precipitados com alta concentração de cromo e molibdênio. Os filmes formados na superfície das amostras sensitizadas apresentaram maior quantidade de óxido de Cromo VI em relação as amostras solubilizadas e ECA7x. Esse óxido é menos resistente a corrosão em meio ácido do que de Cromo III. O filme passivo formado na amostra submetida à DPS apresentou maior quantidade de Cromo III e de molibdênio proporcionando, assim, uma maior resistência à corrosão generalizada.Não recebi financiamentoporUniversidade Federal de São CarlosCâmpus SorocabaPrograma de Pós-Graduação em Ciência dos Materiais - PPGCM-SoUFSCarSensitizaçãoDeformação Plástica Severa (DPS)Extrusão em Canal Angular (ECA)Corrosão IntergranularDeformações (Mecânica)Resistência de materiaisPlásticos - ExtrusãoSensitizationSevere Plastic Deformation (SPD)Equal Channel Angular Pressing (ECAP)Intergranular Corrosion (IGC)Deformations (Mechanics)Strength of materialsPlastics - ExtrusionENGENHARIAS::ENGENHARIA DE MATERIAIS E METALURGICAEstudo da resistência à corrosão intergranular do aço inoxidável austenítico f138 - perspectiva de desempenho após Deformação Plástica Severa (DPS)Study of resistance to intergranular corrosion of austenitic stainless steel f138 - performance perspective after Severe Plastic Deformation (SPD)info:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/masterThesisOnline6006005a0a5ea7-a08f-40ff-b5ad-6295eccae02einfo:eu-repo/semantics/openAccessreponame:Repositório Institucional da UFSCARinstname:Universidade Federal de São Carlos (UFSCAR)instacron:UFSCARORIGINALDissertacao - Rodolfo de Souza Rodrigues.pdfDissertacao - Rodolfo de Souza Rodrigues.pdfapplication/pdf7580891https://repositorio.ufscar.br/bitstream/ufscar/10893/1/Dissertacao%20-%20Rodolfo%20de%20Souza%20Rodrigues.pdf282c5911d46acf6bb1a3515e5cdce307MD51Carta comprovante entrega dissertacao final.pdfCarta comprovante entrega dissertacao final.pdfCarta comprovante que a dissertaçao é o texo finalapplication/pdf51384https://repositorio.ufscar.br/bitstream/ufscar/10893/2/Carta%20comprovante%20entrega%20dissertacao%20final.pdf7eb31d532130d5a184dda167a4e6d1f6MD52Autorizacao para inclusao no repositorio.pdfAutorizacao para inclusao no repositorio.pdfAutorizaçao de inclusao no repositórioapplication/pdf347161https://repositorio.ufscar.br/bitstream/ufscar/10893/3/Autorizacao%20para%20inclusao%20no%20repositorio.pdf63e46f77d231a05ccb66cdb84f519025MD53LICENSElicense.txtlicense.txttext/plain; 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dc.title.por.fl_str_mv |
Estudo da resistência à corrosão intergranular do aço inoxidável austenítico f138 - perspectiva de desempenho após Deformação Plástica Severa (DPS) |
dc.title.alternative.eng.fl_str_mv |
Study of resistance to intergranular corrosion of austenitic stainless steel f138 - performance perspective after Severe Plastic Deformation (SPD) |
title |
Estudo da resistência à corrosão intergranular do aço inoxidável austenítico f138 - perspectiva de desempenho após Deformação Plástica Severa (DPS) |
spellingShingle |
Estudo da resistência à corrosão intergranular do aço inoxidável austenítico f138 - perspectiva de desempenho após Deformação Plástica Severa (DPS) Rodrigues, Rodolfo de Souza Sensitização Deformação Plástica Severa (DPS) Extrusão em Canal Angular (ECA) Corrosão Intergranular Deformações (Mecânica) Resistência de materiais Plásticos - Extrusão Sensitization Severe Plastic Deformation (SPD) Equal Channel Angular Pressing (ECAP) Intergranular Corrosion (IGC) Deformations (Mechanics) Strength of materials Plastics - Extrusion ENGENHARIAS::ENGENHARIA DE MATERIAIS E METALURGICA |
title_short |
Estudo da resistência à corrosão intergranular do aço inoxidável austenítico f138 - perspectiva de desempenho após Deformação Plástica Severa (DPS) |
title_full |
Estudo da resistência à corrosão intergranular do aço inoxidável austenítico f138 - perspectiva de desempenho após Deformação Plástica Severa (DPS) |
title_fullStr |
Estudo da resistência à corrosão intergranular do aço inoxidável austenítico f138 - perspectiva de desempenho após Deformação Plástica Severa (DPS) |
title_full_unstemmed |
Estudo da resistência à corrosão intergranular do aço inoxidável austenítico f138 - perspectiva de desempenho após Deformação Plástica Severa (DPS) |
title_sort |
Estudo da resistência à corrosão intergranular do aço inoxidável austenítico f138 - perspectiva de desempenho após Deformação Plástica Severa (DPS) |
author |
Rodrigues, Rodolfo de Souza |
author_facet |
Rodrigues, Rodolfo de Souza |
author_role |
author |
dc.contributor.authorlattes.por.fl_str_mv |
http://lattes.cnpq.br/2760387813535332 |
dc.contributor.author.fl_str_mv |
Rodrigues, Rodolfo de Souza |
dc.contributor.advisor1.fl_str_mv |
Kliauga, Andrea Madeira |
dc.contributor.advisor1Lattes.fl_str_mv |
http://lattes.cnpq.br/3527528295399928 |
dc.contributor.authorID.fl_str_mv |
8568c7c8-672b-4fea-87a9-7ebee811892c |
contributor_str_mv |
Kliauga, Andrea Madeira |
dc.subject.por.fl_str_mv |
Sensitização Deformação Plástica Severa (DPS) Extrusão em Canal Angular (ECA) Corrosão Intergranular Deformações (Mecânica) Resistência de materiais Plásticos - Extrusão |
topic |
Sensitização Deformação Plástica Severa (DPS) Extrusão em Canal Angular (ECA) Corrosão Intergranular Deformações (Mecânica) Resistência de materiais Plásticos - Extrusão Sensitization Severe Plastic Deformation (SPD) Equal Channel Angular Pressing (ECAP) Intergranular Corrosion (IGC) Deformations (Mechanics) Strength of materials Plastics - Extrusion ENGENHARIAS::ENGENHARIA DE MATERIAIS E METALURGICA |
dc.subject.eng.fl_str_mv |
Sensitization Severe Plastic Deformation (SPD) Equal Channel Angular Pressing (ECAP) Intergranular Corrosion (IGC) Deformations (Mechanics) Strength of materials Plastics - Extrusion |
dc.subject.cnpq.fl_str_mv |
ENGENHARIAS::ENGENHARIA DE MATERIAIS E METALURGICA |
description |
Austenitic stainless steels are widely used in heating and cooling circuits of thermoelectric and nuclear power plants (NPP) in the storage and reprocessing of nuclear fuels, mainly because they have good processability, high resistance to corrosion and creep. In particular in thermonuclear applications there is, however, the trouble of swelling caused by the nucleation of He voids and bubbles within the irradiated material and the increased sensitivity to intergranular corrosion due to the acceleration by diffusion of alloying elements in the material. Using severe plastic deformation (DPS) by the equal channel angular pressing (ECAP), an increase in the bondary area can be achieved as well as an increase in the density of dislocation enhancing He trapping in these regions. In relation to intergranular corrosion, the mechanism acting in most cases is the sensitization caused by precipitation in boundary grain of chromium-rich phases such as Cr23C6 and intermetallic precipitates. Increased plastic deformation (above 15%) can accelerate the sensitization process in austenitic stainless steels. In order to evaluate the effect of DPS on the corrosion resistance in oxidizing media, the ASTM 262 Practice C test was performed on a ASTM F138 steel after solubilization (1h at 1100oC), sensitization (240h at 850oC) and ECAP (7 passes at 300oC). Microstructural characterization was performed to analyze the sensitization process and to verify the corrosion mechanisms using Optical Microscopy (OM), Scanning Electron Microscopy (SEM) together with X-ray Energy Dispersion Spectroscopy (EDS), Transmission Electron Microscopy (TEM), Mapping of crystallographic orientation by diffraction patterns in MET, X-ray Diffraction (DR-X) and X-ray Excited Photoelectron Spectroscopy (XPS). It was verified that while the sensitized material underwent intergranular corrosion the solubilized and ECAP material were subjected to gerenal corrosion. The mass loss in HNO3 was larger for general corrosion than for intergranular corrosion. The passive film of the ECAP sample contained more Chromium III and Molybdenum than in the solubilized sample, and therefore presented higher resistance to corrosion in the HNO3 medium. The sensitized material presented precipitates with high concentration of chromium and molybdenum leaving the surrounding regions more susceptible to intergranular corrosion and by pites. The film formed on the surface of the sensitized samples presented higher amount of the Chromium VI oxide in relation to the solubilized samples and ECA7x. This oxide is less resistant to acid corrosion than Chromium III oxide. The passive film of the ECAP sample contained more Chromium III and Molybdenum than in the solubilized sample, and therefore presented higher resistance to corrosion in the HNO3 medium. |
publishDate |
2018 |
dc.date.issued.fl_str_mv |
2018-10-26 |
dc.date.accessioned.fl_str_mv |
2019-02-04T11:41:30Z |
dc.date.available.fl_str_mv |
2019-02-04T11:41:30Z |
dc.type.status.fl_str_mv |
info:eu-repo/semantics/publishedVersion |
dc.type.driver.fl_str_mv |
info:eu-repo/semantics/masterThesis |
format |
masterThesis |
status_str |
publishedVersion |
dc.identifier.citation.fl_str_mv |
RODRIGUES, Rodolfo de Souza. Estudo da resistência à corrosão intergranular do aço inoxidável austenítico f138 - perspectiva de desempenho após Deformação Plástica Severa (DPS). 2018. Dissertação (Mestrado em Ciência dos Materiais) – Universidade Federal de São Carlos, Sorocaba, 2018. Disponível em: https://repositorio.ufscar.br/handle/ufscar/10893. |
dc.identifier.uri.fl_str_mv |
https://repositorio.ufscar.br/handle/ufscar/10893 |
identifier_str_mv |
RODRIGUES, Rodolfo de Souza. Estudo da resistência à corrosão intergranular do aço inoxidável austenítico f138 - perspectiva de desempenho após Deformação Plástica Severa (DPS). 2018. Dissertação (Mestrado em Ciência dos Materiais) – Universidade Federal de São Carlos, Sorocaba, 2018. Disponível em: https://repositorio.ufscar.br/handle/ufscar/10893. |
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https://repositorio.ufscar.br/handle/ufscar/10893 |
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Universidade Federal de São Carlos Câmpus Sorocaba |
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Programa de Pós-Graduação em Ciência dos Materiais - PPGCM-So |
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Universidade Federal de São Carlos Câmpus Sorocaba |
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