Influence of sigma phase in the corrosion resistance of super duplex stainless steel ASTM A890 grade 1C after isothermal treatment

Detalhes bibliográficos
Autor(a) principal: Daniel de Castro GirÃo
Data de Publicação: 2015
Tipo de documento: Dissertação
Idioma: por
Título da fonte: Biblioteca Digital de Teses e Dissertações da UFC
Texto Completo: http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=15245
Resumo: The super duplex stainless steels are often used in applications where high mechanical strength is required, combined with corrosion resistance, especially in highly aggressive environments. However, when certain manufacturing processes are involved (hot forming or welding, for example) can occur the precipitation of undesirable phases, causing reduction of both mechanical properties as well as corrosion resistance. Particularly between 700 and 900 ÂC may occur sigma phase formation. This phase is responsible for the reduction of corrosion and mechanical resistance of super duplex steels. Through computer simulation in Thermo-CalCÂ program, the phase diagram of ASTM A890 GRADE 1C super duplex stainless steel showed higher precipitated fraction of this phase in 830 ÂC temperature. Thus, this essay aims to evaluate the influence of isothermal treatment time in regards to this material aging, the corrosion resistance due to the formation of sigma phase. The evaluation of corrosion resistance was performed through open circuit potential monitoring, electrochemical impedance and potentiodynamic polarization tests (anodic branch) in 0.5 M H2SO4 solution, 0.5 M H2SO4 + 0.5M HCl and 0.5 M HCl at temperatures of 25, 35 and 45 ÂC. Additionally, a microstructural characterization of this material was performed by quantification phase through optical microscopy, morphological analysis by Scanning and Transmission Electron Microscopy, coupled techniques Electron backscattered diffraction and Electron Energy Dispersion Spectroscopy, and Vickers microhardness measures. The microstructural and morphological characterization confirmed the presence of sigma phase in super duplex stainless steel 1C and that the amount of this phase increases with aging heat treatment time. This phase showed a greater microhardness than the ferrite and austenite phases. The aging heat treatment influenced negatively on corrosion resistance of the steel when exposed to acidic solutions of H2SO4 and HCl at 25 ÂC, mainly when these are present in the same solution, probably due to their low pH. In this solution (H2SO4 + HCl), both increasing the aging heat treatment time as well as the temperature (35 and 45 ÂC), affects negatively the sample corrosion resistance, decreasing acoording a higher content of this phase.
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spelling info:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/masterThesisInfluence of sigma phase in the corrosion resistance of super duplex stainless steel ASTM A890 grade 1C after isothermal treatment InfluÃncia da fase sigma na resistÃncia à corrosÃo do aÃo inoxidÃvel super duplex ASTM A890 grau 1C apÃs tratamento isotÃrmico2015-02-05Walney Silva Araujo21325102562http://lattes.cnpq.br/5265070571589358Pedro de Lima Neto29470293304http://lattes.cnpq.br/2969689646961586Idalina Vieira Aoki01076389830http://lattes.cnpq.br/620292911852999001467844306http://lattes.cnpq.br/8614307679953136Daniel de Castro GirÃoUniversidade Federal do CearÃPrograma de PÃs-GraduaÃÃo em Engenharia e CiÃncia de MateriaisUFCBR Fase sigma Envelhecimento - Tratamento tÃrmicoStainless steel super duplex Corrosion Sigma phase Aging heat treatmentCORROSAOThe super duplex stainless steels are often used in applications where high mechanical strength is required, combined with corrosion resistance, especially in highly aggressive environments. However, when certain manufacturing processes are involved (hot forming or welding, for example) can occur the precipitation of undesirable phases, causing reduction of both mechanical properties as well as corrosion resistance. Particularly between 700 and 900 ÂC may occur sigma phase formation. This phase is responsible for the reduction of corrosion and mechanical resistance of super duplex steels. Through computer simulation in Thermo-CalC program, the phase diagram of ASTM A890 GRADE 1C super duplex stainless steel showed higher precipitated fraction of this phase in 830 ÂC temperature. Thus, this essay aims to evaluate the influence of isothermal treatment time in regards to this material aging, the corrosion resistance due to the formation of sigma phase. The evaluation of corrosion resistance was performed through open circuit potential monitoring, electrochemical impedance and potentiodynamic polarization tests (anodic branch) in 0.5 M H2SO4 solution, 0.5 M H2SO4 + 0.5M HCl and 0.5 M HCl at temperatures of 25, 35 and 45 ÂC. Additionally, a microstructural characterization of this material was performed by quantification phase through optical microscopy, morphological analysis by Scanning and Transmission Electron Microscopy, coupled techniques Electron backscattered diffraction and Electron Energy Dispersion Spectroscopy, and Vickers microhardness measures. The microstructural and morphological characterization confirmed the presence of sigma phase in super duplex stainless steel 1C and that the amount of this phase increases with aging heat treatment time. This phase showed a greater microhardness than the ferrite and austenite phases. The aging heat treatment influenced negatively on corrosion resistance of the steel when exposed to acidic solutions of H2SO4 and HCl at 25 ÂC, mainly when these are present in the same solution, probably due to their low pH. In this solution (H2SO4 + HCl), both increasing the aging heat treatment time as well as the temperature (35 and 45 ÂC), affects negatively the sample corrosion resistance, decreasing acoording a higher content of this phase.Os aÃos inoxidÃveis super duplex sÃo frequentemente utilizados em aplicaÃÃes onde à necessÃria uma grande resistÃncia mecÃnica, combinada a resistÃncia à corrosÃo, especialmente em ambientes de elevada agressividade. Entretanto, ao sofrer determinados processos de fabricaÃÃo (conformaÃÃo a quente ou soldagem, por exemplo), pode ocorrer à precipitaÃÃo de fases indesejÃveis, que causam tanto reduÃÃo de propriedades mecÃnicas quanto afetam a resistÃncia à corrosÃo. Particularmente entre 700 ÂC e 900 ÂC pode ocorrer à formaÃÃo de fase sigma. Esta fase à responsÃvel pela reduÃÃo da resistÃncia à corrosÃo e mecÃnica dos aÃos inoxidÃveis super duplex. Por meio de simulaÃÃo computacional no programa Thermo-CalCÂ, o diagrama de fases do aÃo inoxidÃvel super duplex ASTM A890 GRAU 1C apresentou maior fraÃÃo precipitada desta fase na temperatura de 830 ÂC. Assim, o presente trabalho tem por objetivo avaliar a influÃncia do tempo de tratamento isotÃrmico de envelhecimento deste material, na resistÃncia à corrosÃo devido à formaÃÃo da fase sigma. A avaliaÃÃo da resistÃncia à corrosÃo foi realizada por meio do monitoramento do potencial de circuito aberto, impedÃncia eletroquÃmica e de ensaios de polarizaÃÃo potenciodinÃmica (ramo anÃdico) em soluÃÃo de H2SO4 0,5 M, H2SO4 0,5 M + HCl 0,5 M e HCl 0,5 M, nas temperaturas de 25, 35 e 45 ÂC. Adicionalmente, foi realizada a caracterizaÃÃo microestrutural desse material atravÃs de quantificaÃÃo de fases por microscopia Ãtica, anÃlise morfolÃgica por Microscopia EletrÃnica de Varredura e TransmissÃo, acoplados as tÃcnicas de DifraÃÃo de ElÃtrons Retroespalhados e Espectroscopia de DispersÃo de Energia de ElÃtrons, alÃm de medidas de microdureza vickers. A caracterizaÃÃo microestrutural e morfolÃgica confirmou a presenÃa de fase sigma no aÃo inoxidÃvel super duplex 1C e que a quantidade desta fase aumenta com o tempo de tratamento tÃrmico de envelhecimento. Esta fase apresentou microdureza maior que as fases ferrita e austenita. O tratamento tÃrmico de envelhecimento influenciou de maneira negativa na resistÃncia a corrosÃo desse aÃo quando exposto a soluÃÃes Ãcidas de H2SO4 e HCl a 25 C, principalmente quando este estÃo presentes na mesma soluÃÃo, devido provavelmente ao seu baixo pH. Nesta soluÃÃo (H2SO4 + HCl), tanto o aumento do tempo de tratamento tÃrmico de envelhecimento quanto o aumento da temperatura (35 e 45 ÂC), afetam negativamente na resistÃncia à corrosÃo do material estudado, diminuindo à medida que se tem um maior conteÃdo de fase sigma. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=15245application/pdfinfo:eu-repo/semantics/openAccessporreponame:Biblioteca Digital de Teses e Dissertações da UFCinstname:Universidade Federal do Cearáinstacron:UFC2019-01-21T11:28:27Zmail@mail.com -
dc.title.en.fl_str_mv Influence of sigma phase in the corrosion resistance of super duplex stainless steel ASTM A890 grade 1C after isothermal treatment
dc.title.alternative.pt.fl_str_mv InfluÃncia da fase sigma na resistÃncia à corrosÃo do aÃo inoxidÃvel super duplex ASTM A890 grau 1C apÃs tratamento isotÃrmico
title Influence of sigma phase in the corrosion resistance of super duplex stainless steel ASTM A890 grade 1C after isothermal treatment
spellingShingle Influence of sigma phase in the corrosion resistance of super duplex stainless steel ASTM A890 grade 1C after isothermal treatment
Daniel de Castro GirÃo
Fase sigma
Envelhecimento - Tratamento tÃrmico
Stainless steel super duplex
Corrosion
Sigma phase
Aging heat treatment
CORROSAO
title_short Influence of sigma phase in the corrosion resistance of super duplex stainless steel ASTM A890 grade 1C after isothermal treatment
title_full Influence of sigma phase in the corrosion resistance of super duplex stainless steel ASTM A890 grade 1C after isothermal treatment
title_fullStr Influence of sigma phase in the corrosion resistance of super duplex stainless steel ASTM A890 grade 1C after isothermal treatment
title_full_unstemmed Influence of sigma phase in the corrosion resistance of super duplex stainless steel ASTM A890 grade 1C after isothermal treatment
title_sort Influence of sigma phase in the corrosion resistance of super duplex stainless steel ASTM A890 grade 1C after isothermal treatment
author Daniel de Castro GirÃo
author_facet Daniel de Castro GirÃo
author_role author
dc.contributor.advisor1.fl_str_mv Walney Silva Araujo
dc.contributor.advisor1ID.fl_str_mv 21325102562
dc.contributor.advisor1Lattes.fl_str_mv http://lattes.cnpq.br/5265070571589358
dc.contributor.advisor-co1.fl_str_mv Pedro de Lima Neto
dc.contributor.advisor-co1ID.fl_str_mv 29470293304
dc.contributor.advisor-co1Lattes.fl_str_mv http://lattes.cnpq.br/2969689646961586
dc.contributor.referee1.fl_str_mv Idalina Vieira Aoki
dc.contributor.referee1ID.fl_str_mv 01076389830
dc.contributor.referee1Lattes.fl_str_mv http://lattes.cnpq.br/6202929118529990
dc.contributor.authorID.fl_str_mv 01467844306
dc.contributor.authorLattes.fl_str_mv http://lattes.cnpq.br/8614307679953136
dc.contributor.author.fl_str_mv Daniel de Castro GirÃo
contributor_str_mv Walney Silva Araujo
Pedro de Lima Neto
Idalina Vieira Aoki
dc.subject.por.fl_str_mv Fase sigma
Envelhecimento - Tratamento tÃrmico
topic Fase sigma
Envelhecimento - Tratamento tÃrmico
Stainless steel super duplex
Corrosion
Sigma phase
Aging heat treatment
CORROSAO
dc.subject.eng.fl_str_mv Stainless steel super duplex
Corrosion
Sigma phase
Aging heat treatment
dc.subject.cnpq.fl_str_mv CORROSAO
dc.description.abstract.por.fl_txt_mv The super duplex stainless steels are often used in applications where high mechanical strength is required, combined with corrosion resistance, especially in highly aggressive environments. However, when certain manufacturing processes are involved (hot forming or welding, for example) can occur the precipitation of undesirable phases, causing reduction of both mechanical properties as well as corrosion resistance. Particularly between 700 and 900 ÂC may occur sigma phase formation. This phase is responsible for the reduction of corrosion and mechanical resistance of super duplex steels. Through computer simulation in Thermo-CalCÂ program, the phase diagram of ASTM A890 GRADE 1C super duplex stainless steel showed higher precipitated fraction of this phase in 830 ÂC temperature. Thus, this essay aims to evaluate the influence of isothermal treatment time in regards to this material aging, the corrosion resistance due to the formation of sigma phase. The evaluation of corrosion resistance was performed through open circuit potential monitoring, electrochemical impedance and potentiodynamic polarization tests (anodic branch) in 0.5 M H2SO4 solution, 0.5 M H2SO4 + 0.5M HCl and 0.5 M HCl at temperatures of 25, 35 and 45 ÂC. Additionally, a microstructural characterization of this material was performed by quantification phase through optical microscopy, morphological analysis by Scanning and Transmission Electron Microscopy, coupled techniques Electron backscattered diffraction and Electron Energy Dispersion Spectroscopy, and Vickers microhardness measures. The microstructural and morphological characterization confirmed the presence of sigma phase in super duplex stainless steel 1C and that the amount of this phase increases with aging heat treatment time. This phase showed a greater microhardness than the ferrite and austenite phases. The aging heat treatment influenced negatively on corrosion resistance of the steel when exposed to acidic solutions of H2SO4 and HCl at 25 ÂC, mainly when these are present in the same solution, probably due to their low pH. In this solution (H2SO4 + HCl), both increasing the aging heat treatment time as well as the temperature (35 and 45 ÂC), affects negatively the sample corrosion resistance, decreasing acoording a higher content of this phase.
Os aÃos inoxidÃveis super duplex sÃo frequentemente utilizados em aplicaÃÃes onde à necessÃria uma grande resistÃncia mecÃnica, combinada a resistÃncia à corrosÃo, especialmente em ambientes de elevada agressividade. Entretanto, ao sofrer determinados processos de fabricaÃÃo (conformaÃÃo a quente ou soldagem, por exemplo), pode ocorrer à precipitaÃÃo de fases indesejÃveis, que causam tanto reduÃÃo de propriedades mecÃnicas quanto afetam a resistÃncia à corrosÃo. Particularmente entre 700 ÂC e 900 ÂC pode ocorrer à formaÃÃo de fase sigma. Esta fase à responsÃvel pela reduÃÃo da resistÃncia à corrosÃo e mecÃnica dos aÃos inoxidÃveis super duplex. Por meio de simulaÃÃo computacional no programa Thermo-CalCÂ, o diagrama de fases do aÃo inoxidÃvel super duplex ASTM A890 GRAU 1C apresentou maior fraÃÃo precipitada desta fase na temperatura de 830 ÂC. Assim, o presente trabalho tem por objetivo avaliar a influÃncia do tempo de tratamento isotÃrmico de envelhecimento deste material, na resistÃncia à corrosÃo devido à formaÃÃo da fase sigma. A avaliaÃÃo da resistÃncia à corrosÃo foi realizada por meio do monitoramento do potencial de circuito aberto, impedÃncia eletroquÃmica e de ensaios de polarizaÃÃo potenciodinÃmica (ramo anÃdico) em soluÃÃo de H2SO4 0,5 M, H2SO4 0,5 M + HCl 0,5 M e HCl 0,5 M, nas temperaturas de 25, 35 e 45 ÂC. Adicionalmente, foi realizada a caracterizaÃÃo microestrutural desse material atravÃs de quantificaÃÃo de fases por microscopia Ãtica, anÃlise morfolÃgica por Microscopia EletrÃnica de Varredura e TransmissÃo, acoplados as tÃcnicas de DifraÃÃo de ElÃtrons Retroespalhados e Espectroscopia de DispersÃo de Energia de ElÃtrons, alÃm de medidas de microdureza vickers. A caracterizaÃÃo microestrutural e morfolÃgica confirmou a presenÃa de fase sigma no aÃo inoxidÃvel super duplex 1C e que a quantidade desta fase aumenta com o tempo de tratamento tÃrmico de envelhecimento. Esta fase apresentou microdureza maior que as fases ferrita e austenita. O tratamento tÃrmico de envelhecimento influenciou de maneira negativa na resistÃncia a corrosÃo desse aÃo quando exposto a soluÃÃes Ãcidas de H2SO4 e HCl a 25 C, principalmente quando este estÃo presentes na mesma soluÃÃo, devido provavelmente ao seu baixo pH. Nesta soluÃÃo (H2SO4 + HCl), tanto o aumento do tempo de tratamento tÃrmico de envelhecimento quanto o aumento da temperatura (35 e 45 ÂC), afetam negativamente na resistÃncia à corrosÃo do material estudado, diminuindo à medida que se tem um maior conteÃdo de fase sigma.
description The super duplex stainless steels are often used in applications where high mechanical strength is required, combined with corrosion resistance, especially in highly aggressive environments. However, when certain manufacturing processes are involved (hot forming or welding, for example) can occur the precipitation of undesirable phases, causing reduction of both mechanical properties as well as corrosion resistance. Particularly between 700 and 900 ÂC may occur sigma phase formation. This phase is responsible for the reduction of corrosion and mechanical resistance of super duplex steels. Through computer simulation in Thermo-CalCÂ program, the phase diagram of ASTM A890 GRADE 1C super duplex stainless steel showed higher precipitated fraction of this phase in 830 ÂC temperature. Thus, this essay aims to evaluate the influence of isothermal treatment time in regards to this material aging, the corrosion resistance due to the formation of sigma phase. The evaluation of corrosion resistance was performed through open circuit potential monitoring, electrochemical impedance and potentiodynamic polarization tests (anodic branch) in 0.5 M H2SO4 solution, 0.5 M H2SO4 + 0.5M HCl and 0.5 M HCl at temperatures of 25, 35 and 45 ÂC. Additionally, a microstructural characterization of this material was performed by quantification phase through optical microscopy, morphological analysis by Scanning and Transmission Electron Microscopy, coupled techniques Electron backscattered diffraction and Electron Energy Dispersion Spectroscopy, and Vickers microhardness measures. The microstructural and morphological characterization confirmed the presence of sigma phase in super duplex stainless steel 1C and that the amount of this phase increases with aging heat treatment time. This phase showed a greater microhardness than the ferrite and austenite phases. The aging heat treatment influenced negatively on corrosion resistance of the steel when exposed to acidic solutions of H2SO4 and HCl at 25 ÂC, mainly when these are present in the same solution, probably due to their low pH. In this solution (H2SO4 + HCl), both increasing the aging heat treatment time as well as the temperature (35 and 45 ÂC), affects negatively the sample corrosion resistance, decreasing acoording a higher content of this phase.
publishDate 2015
dc.date.issued.fl_str_mv 2015-02-05
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dc.publisher.initials.fl_str_mv UFC
dc.publisher.country.fl_str_mv BR
publisher.none.fl_str_mv Universidade Federal do CearÃ
dc.source.none.fl_str_mv reponame:Biblioteca Digital de Teses e Dissertações da UFC
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