Kinetics of sigma phase formation in a Duplex Stainless Steel

This work determines the kinetics of sigma phase formation in UNS S31803 Duplex Stainless Steel (DSS), describing the phase transformations that occur in isothermal aging between 700 and 900 ºC for time periods up to 1032 hours, allowing the determination of the Time-Temperature-Precipitation (TTP)...

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Main Author: Rodrigo Magnabosco
Format: Article
Language:English
Published: Associação Brasileira de Metalurgia e Materiais (ABM); Associação Brasileira de Cerâmica (ABC); Associação Brasileira de Polímeros (ABPol) 2009-09-01
Series:Materials Research
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Online Access:http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392009000300012
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author Rodrigo Magnabosco
author_facet Rodrigo Magnabosco
author_sort Rodrigo Magnabosco
collection DOAJ
description This work determines the kinetics of sigma phase formation in UNS S31803 Duplex Stainless Steel (DSS), describing the phase transformations that occur in isothermal aging between 700 and 900 ºC for time periods up to 1032 hours, allowing the determination of the Time-Temperature-Precipitation (TTP) diagram for sigma phase and proposing a model to predict the kinetics of sigma phase formation using a Johnson-Mehl-Avrami (JMA) type expression. The higher kinetics of sigma phase formation occurs at 850 ºC. However, isothermal aging between 700 and 900 ºC for time periods up to 1032 hours are not sufficient to the establishment of thermodynamic equilibrium. Activation energy for both nucleation and growth of sigma phase is determined (185 kJ.mol-1) and its value is equivalent to the activation energy for Cr diffusion in ferrite, indicating that diffusion of Cr is probably the major thermally activated process involved in sigma phase formation. The determined JMA type expression presents good fit with experimental data between 700 and 850 ºC.
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publishDate 2009-09-01
publisher Associação Brasileira de Metalurgia e Materiais (ABM); Associação Brasileira de Cerâmica (ABC); Associação Brasileira de Polímeros (ABPol)
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spelling doaj.art-54ec6e6c02894e48b5df3eedd10ed1df2022-12-21T20:09:43ZengAssociação Brasileira de Metalurgia e Materiais (ABM); Associação Brasileira de Cerâmica (ABC); Associação Brasileira de Polímeros (ABPol)Materials Research1516-14392009-09-0112332132710.1590/S1516-14392009000300012Kinetics of sigma phase formation in a Duplex Stainless SteelRodrigo MagnaboscoThis work determines the kinetics of sigma phase formation in UNS S31803 Duplex Stainless Steel (DSS), describing the phase transformations that occur in isothermal aging between 700 and 900 ºC for time periods up to 1032 hours, allowing the determination of the Time-Temperature-Precipitation (TTP) diagram for sigma phase and proposing a model to predict the kinetics of sigma phase formation using a Johnson-Mehl-Avrami (JMA) type expression. The higher kinetics of sigma phase formation occurs at 850 ºC. However, isothermal aging between 700 and 900 ºC for time periods up to 1032 hours are not sufficient to the establishment of thermodynamic equilibrium. Activation energy for both nucleation and growth of sigma phase is determined (185 kJ.mol-1) and its value is equivalent to the activation energy for Cr diffusion in ferrite, indicating that diffusion of Cr is probably the major thermally activated process involved in sigma phase formation. The determined JMA type expression presents good fit with experimental data between 700 and 850 ºC.http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392009000300012duplex stainless steelssigma phasephase transformationskinetics
spellingShingle Rodrigo Magnabosco
Kinetics of sigma phase formation in a Duplex Stainless Steel
Materials Research
duplex stainless steels
sigma phase
phase transformations
kinetics
title Kinetics of sigma phase formation in a Duplex Stainless Steel
title_full Kinetics of sigma phase formation in a Duplex Stainless Steel
title_fullStr Kinetics of sigma phase formation in a Duplex Stainless Steel
title_full_unstemmed Kinetics of sigma phase formation in a Duplex Stainless Steel
title_short Kinetics of sigma phase formation in a Duplex Stainless Steel
title_sort kinetics of sigma phase formation in a duplex stainless steel
topic duplex stainless steels
sigma phase
phase transformations
kinetics
url http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392009000300012
work_keys_str_mv AT rodrigomagnabosco kineticsofsigmaphaseformationinaduplexstainlesssteel