Microstructural evolution and localized corrosion resistance of an aged superduplex stainless steel

Angelini, Emma Paola Maria Virginia; Benedetti, Bruno; Rosalbino, Francesco

doi:10.1016/j.corsci.2003.09.024

Cited by 100 publications

(71 citation statements)

References 12 publications

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“…Besides, the high temperature and long aging time also promotes the Cr and Mo diffusion, reducing the amount of chromium and molybdenum depleted boundaries, resulting in a lower value of I r /I a and Q r /Q a . This healing process was reported by Angelini et al 20 . A clear example of desensitization process is shown by specimens aged at 950 °C, Figures 7 and 8.…”

Section: Influence Of Deleterious Phases Precipitation In the Corrosimentioning

confidence: 55%

Influence of Deleterious Phases Precipitation in the Corrosion Resistance Measured by Double Loop Electrochemical Polarization Reactivation Test in Superduplex Stainless Steel

et al. 2015

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This work investigates the influence of deleterious phases precipitation on the corrosion resistance of two wrought superduplex stainless steels UNS S32750 with similar composition, but different grain sizes. Isothermal treatments were carried out to introduce different amounts of deleterious phases, such as chi (χ), sigma (σ) and secondary austenite (γ 2 ). The specimens were tested by double loop electrochemical potentiodynamic reactivation test (DL-EPR). The kinetics of precipitation in the two steels was different due to the difference of the grain sizes. The results show a correlation between the sensitization degrees, measured by DL-EPR, with the amount of deleterious phases precipitated.

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Section: Influence Of Deleterious Phases Precipitation In the Corrosimentioning

confidence: 55%

Influence of Deleterious Phases Precipitation in the Corrosion Resistance Measured by Double Loop Electrochemical Polarization Reactivation Test in Superduplex Stainless Steel

et al. 2015

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“…ANGELINI et al [7] efetuaram ensaios de polarização cíclica, em um AISD, à temperatura ambiente em uma solução desaerada contendo 3,5% em peso de NaCl. Nestas experiências observou-se que grandes tempos de tratamento aumentam a susceptibilidade da liga à corrosão localizada a 700 ºC e 800 ºC, pois as curvas de polarização foram caracterizadas por um baixo potencial de pites (E p ) e um extenso ciclo de histerese.…”

Section: Introductionunclassified

Estudo da Influência da precipitação de fases deletérias na resistência à corrosão por ensaio de polarização anódica cíclica em aços inoxidáveis superduplex

et al. 2015

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A influência da precipitação de fases deletérias na resistência à corrosão em dois aços inoxidáveis superduplex (AISD) UNS S32750 com diferentes tamanhos de grão foi investigada. Foram realizados tratamentos isotérmicos de modo a introduzir na microestrutura diversas quantidades de fases deletérias, tais como chi, sigma, austenita secundária e nitretos de cromo. Nestas condições foram efetuados ensaios de corrosão por polarização anódica cíclica. Estudos por microscopias ótica (MO) e eletrônica de varredura (MEV) foram realizados para caracterizar as fases precipitadas e a sua cinética de precipitação. Os resultados permitem correlacionar os valores obtidos pelos ensaios de polarização com o percentual de fases deletérias precipitadas para diferentes condições de tratamento em AISD com composições similares, mas com diferentes tamanhos de grão. Observou-se ainda que o tamanho de grão e a temperatura de envelhecimento influem na cinética de precipitação, na morfologia e no tamanho das fases deletérias precipitadas, incidindo na resistência à corrosão por pites dos AISD. Palavras-chave:Aços inoxidáveis superduplex, Resistência à corrosão, Ensaio de polarização anódica cíclica. ABSTRACTThe influence of deleterious phases precipitation in corrosion resistance was investigated in two superduplex stainless steel (SDSS) UNS S32750 with different grain sizes. Isothermal treatments were performed in order to introduce various quantities of deleterious phases, such as chi, sigma, secondary austenite and chromium nitrides. Under these conditions corrosion tests were carried out by cyclic anodic polarization method. Studies by light optical microscopy (LOM) and scanning electron microscopy (SEM) were performed to characterize the precipitated phases and the precipitation kinetics. The results allow to correlate the values obtained by polarization tests with the percentage of deleterious phases precipitates to the different conditions of treatments of SDSS with similar compositions, but with different grain sizes. It was observed that the grain sizes and aging temperature influence the kinetics of precipitation, morphology and size of deleterious phases. These features affect the corrosion resistance of SDSS.

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“…In the ferritic stainless steels (Fe-29Cr-4Mo), the phase precipitates in the grain boundaries during isothermal aging treatment at 1123 K in the early stage, and the volume fraction of the phase reached 20% after aging at 1123 K for 36 ks. 7) In the 25Cr duplex stainless steel alloys, Agelini et al 8) reported that the volume fraction of the phase reached 2.5 and 5 vol% after aging at 923 K for 3.6 ks and 14.4 ks, respectively. Furthermore, Aguilar et al 9) reported the volume fraction of the phase reaches approximately 5 vol% even if after aging at 1123 K for 0.3 ks.…”

Section: Introductionmentioning

confidence: 99%

Effect of Sigma Phase in Co-29Cr-6Mo Alloy on Corrosion Behavior in Saline Solution

2006

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Effect of the sigma () phase in Co-29Cr-6Mo alloy on corrosion behavior in saline solution has been investigated. The area fraction of the phase contained in Co-29Cr-6Mo alloy varies depending on the aging time at 1023 K. The phase is mainly observed at grain boundaries. The area fraction of the phase increases with increasing aging time and reaches 0.6% after aging at 1023 K for 21.6 ks.The Co-29Cr-6Mo alloys aged at 1023 K for various aging times were immersed in saline solution at 310 K for 1 week and metal ions released from the alloys were examined by inductively coupled plasma atomic emission spectrometer (ICP-AES). The quantity of a released Co ion does not depend on the aging time and shows almost the same value regardless of the different area fraction of the phase, while that of released Cr, Mo and Ni ions increases with increasing area fraction of the phase. Results of polarization test in saline solution at 310 K revealed that passive current density and breakdown potential of Co-29Cr-6Mo alloys aged at 1023 K for various aging times exhibit almost the same values, although the alloys have different area fraction of the phase. These results suggest that a small amount of the phase (<0:6%) hardly affect the formation and breakdown of passive film in the Co-29Cr-6Mo alloy aged at 1023 K.

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Microstructural evolution and localized corrosion resistance of an aged superduplex stainless steel

Cited by 100 publications

References 12 publications

Influence of Deleterious Phases Precipitation in the Corrosion Resistance Measured by Double Loop Electrochemical Polarization Reactivation Test in Superduplex Stainless Steel

Influence of Deleterious Phases Precipitation in the Corrosion Resistance Measured by Double Loop Electrochemical Polarization Reactivation Test in Superduplex Stainless Steel

Estudo da Influência da precipitação de fases deletérias na resistência à corrosão por ensaio de polarização anódica cíclica em aços inoxidáveis superduplex

Effect of Sigma Phase in Co-29Cr-6Mo Alloy on Corrosion Behavior in Saline Solution

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