Kinetics of sigma phase formation in a Duplex Stainless Steel

Magnabosco, Rodrigo

doi:10.1590/s1516-14392009000300012

Cited by 188 publications

(127 citation statements)

References 14 publications

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“…The kinetics of sigma formation measured in this study is consistent with that reported by Magnabosco 4 and with the results of Elmer et al 2 obtained using In-situ Synchrotron X-Ray Diffraction. More important than the kinetic measurements, however, is the indication that the Barkhausen noise signal can be adequately used to assess the decrease in ferromagnetic phase over time, thus making it a valuable non-destructive technique.…”

Section: Barkhausen Noise Measurementssupporting

confidence: 93%

“…Since σ is the intermetallic phase more prominently formed during field applications of duplex stainless steel, its formation has been the object of several studies throughout the years, mostly focused on morphology and formation kinetics [1][2][3][4][5][6][7][8] , as well as its effects on mechanical properties [9][10][11] and corrosion resistance [12][13][14][15][16][17] . Processes that include high temperature thermal cycling, such as welding, are particularly critical regarding the appearance of σ, due to the temperature range to which the heat affected zone is exposed in a poorly controlled manner.…”

Section: Introductionmentioning

confidence: 99%

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Use of Magnetic Barkhausen Noise (MBN) to Follow Up the Formation of Sigma Phase in Saf2205 (UNS S31803) Duplex Stainless Steel

et al. 2016

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Duplex stainless steels have a structure normally composed of austenite and ferrite in approximately equal proportions. In order to attain control of its fabrication processes and performance, it is important to understand its microstructural evolution, due to the formation of intermetallic phases such as sigma (σ) and chi (χ), which may cause a severe deterioration of mechanical properties. In the present study, the evolution of sigma phase during heat treatments at temperatures in which intermetallic phases can be formed (800ºC-900°C) was studied using magnetic analyses on a SAF2205 (DIN 1.4462/UNS S31803) steel. A significant reduction of the intensity of Magnetic Barkhausen Noise (MBN) was observed with the increase of heat treatment time, indicating a decrease in the quantity of ferromagnetic phases. For 24-hour-long treatments, the Barkhausen Noise signal is almost completely enclosed by the background noise, indicating the existence of a very small volume fraction of ferrite. If proper calibration samples are to be produced, this technique may be a viable method for non-destructive evaluation of field components working under thermal conditions that may cause the formation of intermetallic phases.

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Section: Barkhausen Noise Measurementssupporting

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Use of Magnetic Barkhausen Noise (MBN) to Follow Up the Formation of Sigma Phase in Saf2205 (UNS S31803) Duplex Stainless Steel

et al. 2016

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“…One physical method for determining the evolution of sigma phase is to measure magnetically the change in the volume fraction of ferrite [8].…”

Section: Introductionmentioning

confidence: 99%

Quantification of sigma-phase evolution in thermally aged 2205 duplex stainless steel

et al. 2015

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In this study, the evolution of sigma-phase development in a 2205 duplex steel was studied following thermal ageing in the temperature range 750-850°C for periods up to 100 h. A suite of materials analysis techniques including combined electron backscatter diffraction-energy-dispersive X-ray imaging and magnetic force microscopy are used to quantify the change in volume fraction of the phases. The experimental results for each ageing condition are compared with the results from other ageing experiments and the predictions from the computer modelling. They show good correlation for the amount of sigma phase formed under a range of ageing conditions (and thus varying quantities of sigma phase). EBSD measurements showed no preferential orientation relationships relative to the parent ferrite for the nucleation of sigma phase, implying that the minimisation of boundary misorientation energy is not significant in determining sigma-phase nucleation sites. The results are discussed with respect to the experimentally measured properties of sigma phase and the kinetics of the precipitation process.

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“…Estas alterações metalúrgicas dizem respeito à precipitação de fases intermetálicas, como a fase sigma, que se presente, mesmo em pequenas quantidades, leva a efeitos deletérios em relação às propriedades Haskel et al mecânicas e de resistência à corrosão. Existem duas faixas de temperaturas que podem levar a precipitações nos aços inoxidáveis duplex, sendo elas a temperatura de 475 °C que é responsável pela precipitação da fase alfa linha (α') e a faixa de temperatura entre 600 e 900 °C na qual precipitam fases tais como a sigma (σ), chi (ϗ), austenita secundária (γ 2 ), carbetos tais como o M 7 C 3 e o M 23 C 6 e o nitreto Cr 2 N [5][6][7][8].…”

Section: Introductionunclassified

Avaliação da Técnica de Voltametria Linear para Determinação Quantitativa de Fase Sigma no Aço Inoxidável Duplex UNS S31803

et al. 2015

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Este é um artigo publicado em acesso aberto (Open Access) sob a licença Creative Commons Attribution Non-Commercial, que permite uso, distribuição e reprodução em qualquer meio, sem restrições desde que sem fins comerciais e que o trabalho original seja corretamente citado. Linear Voltammetry Assessment to Quantitative Determination of the Sigma Phase in Duplex Stainless Steel UNS S31803Abstract: Precipitation of intermetallic phases in duplex stainless steels constitute a problem regarding the use of such materials in certain temperature ranges, in this way, are necessary methods to quantify, non-destructively, the presence of microstructural changes due to thermal contribution. In this work, electrochemical tests of linear voltammetry, tensile and Vickers hardness were performed in duplex stainless steel UNS S31803 for evaluation of the intermetallic sigma phase presence in the microstructure of the material. Samples of this steel were isothermally aged at 870 °C for times up to 3600 seconds to induce the precipitation of different grades of this phase. Linear voltametry tests were conducted in 5% KOH electrolyte solution in an electrochemical cell 3.3.10 -6 m 2 , with a reference electrode of the type Saturated Calomel and auxiliary electrode of platinum wire. The results of this technique showed sensitivity to detect sigma phase content greater than 1% in the material enabling its application as a Non-Destructive Testing (NDT).Key-words: Duplex steel; Deleterious phases; Sigma phase; Linear voltammetry. IntroduçãoOs aços inoxidáveis duplex foram estudados extensivamente ao longo dos anos por apresentarem boas características em relação à resistência mecânica e a corrosão. Estas características se devem a sua microestrutura balanceada de ferrita e austenita, onde a resistência mecânica se deve a boa correlação das propriedades individuais destas fases, e a resistência à corrosão ao cromo em sua estrutura, formando um filme passivador [1].No entanto, componentes fabricados a partir deste material que operem em determinadas faixas de temperatura ou que sejam submetidos a algum gradiente térmico durante a fabricação, tal como ocorre na conformação a quente ou durante o processo de soldagem, podem sofrer alterações metalúrgicas em sua microestrutura e, consequentemente, perda das propriedades originais [2][3][4]. Estas alterações metalúrgicas dizem respeito à precipitação de fases intermetálicas, como a fase sigma, que se presente, mesmo em pequenas quantidades, leva a efeitos deletérios em relação às propriedades

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Kinetics of sigma phase formation in a Duplex Stainless Steel

Cited by 188 publications

References 14 publications

Use of Magnetic Barkhausen Noise (MBN) to Follow Up the Formation of Sigma Phase in Saf2205 (UNS S31803) Duplex Stainless Steel

Use of Magnetic Barkhausen Noise (MBN) to Follow Up the Formation of Sigma Phase in Saf2205 (UNS S31803) Duplex Stainless Steel

Quantification of sigma-phase evolution in thermally aged 2205 duplex stainless steel

Avaliação da Técnica de Voltametria Linear para Determinação Quantitativa de Fase Sigma no Aço Inoxidável Duplex UNS S31803

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