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Modeling of Fe–Cr martensitic steels corrosion in liquid lead alloys / F. Balbaud-Célérier in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 10 (Octobre 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 10 (Octobre 2010) . - 09 p. Titre : Modeling of Fe–Cr martensitic steels corrosion in liquid lead alloys Type de document : texte imprimé Auteurs : F. Balbaud-Célérier, Auteur ; L. Martinelli, Auteur Année de publication : 2011 Article en page(s) : 09 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Bismuth  alloys  Chromium  alloys  Corrosion  Dissolving  Fission  reactor  coolants  Fission  reactor  cooling  Iron  alloys  Lead  alloys  Liquid  alloys  Martensitic  steel  Oxidation Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Among the Generation IV systems, sodium fast reactors (SFRs) are promising and benefits of considerable technological experience. However, the availability and acceptability of the SFR are affected by the problems linked with the sodium-water reaction. One innovative solution to this problem is the replacement of the sodium in the secondary loops by an alternative liquid fluid. Among the fluids considered, lead-bismuth is at the moment being evaluated. Liquid lead-bismuth has been considerably studied in the frame of the research program on accelerator driven systems for transmutation applications. However, lead alloys are corrosive toward structural materials. The main parameters impacting the corrosion rate of Fe–Cr martensitic steels (considered as structural materials) are the nature of the steel (material side), temperature, liquid alloy velocity, and dissolved oxygen concentration (liquid alloy side). In this study, attention is focused on the behavior of Fe-9Cr steels, and more particularly, T91 martensitic steel. It has been shown that in the case of Fe–Cr martensitic steels, the corrosion process depends on the concentration of oxygen dissolved in Pb–Bi. For an oxygen concentration lower than the one necessary for magnetite formation (approximately <10−8 wt % at T[approximate]500°C for Fe-9Cr steels), corrosion proceeds by dissolution of the steel. For a higher oxygen content dissolved in Pb–Bi, corrosion proceeds by oxidation of the steel. These two corrosion processes have been experimentally and theoretically studied in CEA Saclay and also by other partners, leading to some corrosion modeling in order to predict the life duration of these materials as well as their limits of utilization. This study takes into account the two kinds of corrosion processes: dissolution and oxidation. In these two different processes, the lead alloy physico-chemical parameters are considered: the temperature and the liquid alloy velocity for both processes and the oxygen concentration for oxidation. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] Modeling of Fe–Cr martensitic steels corrosion in liquid lead alloys [texte imprimé] / F. Balbaud-Célérier, Auteur ; L. Martinelli, Auteur . - 2011 . - 09 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 10 (Octobre 2010) . - 09 p. Mots-clés : Bismuth  alloys  Chromium  alloys  Corrosion  Dissolving  Fission  reactor  coolants  Fission  reactor  cooling  Iron  alloys  Lead  alloys  Liquid  alloys  Martensitic  steel  Oxidation Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Among the Generation IV systems, sodium fast reactors (SFRs) are promising and benefits of considerable technological experience. However, the availability and acceptability of the SFR are affected by the problems linked with the sodium-water reaction. One innovative solution to this problem is the replacement of the sodium in the secondary loops by an alternative liquid fluid. Among the fluids considered, lead-bismuth is at the moment being evaluated. Liquid lead-bismuth has been considerably studied in the frame of the research program on accelerator driven systems for transmutation applications. However, lead alloys are corrosive toward structural materials. The main parameters impacting the corrosion rate of Fe–Cr martensitic steels (considered as structural materials) are the nature of the steel (material side), temperature, liquid alloy velocity, and dissolved oxygen concentration (liquid alloy side). In this study, attention is focused on the behavior of Fe-9Cr steels, and more particularly, T91 martensitic steel. It has been shown that in the case of Fe–Cr martensitic steels, the corrosion process depends on the concentration of oxygen dissolved in Pb–Bi. For an oxygen concentration lower than the one necessary for magnetite formation (approximately <10−8 wt % at T[approximate]500°C for Fe-9Cr steels), corrosion proceeds by dissolution of the steel. For a higher oxygen content dissolved in Pb–Bi, corrosion proceeds by oxidation of the steel. These two corrosion processes have been experimentally and theoretically studied in CEA Saclay and also by other partners, leading to some corrosion modeling in order to predict the life duration of these materials as well as their limits of utilization. This study takes into account the two kinds of corrosion processes: dissolution and oxidation. In these two different processes, the lead alloy physico-chemical parameters are considered: the temperature and the liquid alloy velocity for both processes and the oxygen concentration for oxidation. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

Modelling of the oxide scale formation on Fe-Cr steel during exposure in liquid lead-bismuth eutectic in the 450–600 °C temperature range / L. Martinelli in Materials and corrosion, Vol. 62 N° 6 (Juin 2011) 

Public ISBD [article]  in Materials and corrosion > Vol. 62 N° 6 (Juin 2011) . - pp. 531–542 Titre : Modelling of the oxide scale formation on Fe-Cr steel during exposure in liquid lead-bismuth eutectic in the 450–600 °C temperature range Type de document : texte imprimé Auteurs : L. Martinelli, Auteur ; F. Balbaud-Célérier, Auteur Année de publication : 2011 Article en page(s) : pp. 531–542 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Fe-Cr  Magnetite,  Spinel  Oxidation  mechanism  Pb-Bi Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Previous studies showed that the oxidation of T91 (Fe-9Cr martensitic steel) in liquid Pb-Bi eutectic leads to the formation of a duplex oxide layer containing an inner Fe2.3Cr0.7O4 spinel layer and an upper magnetite layer. The magnetite layer is easily removed by the Pb-Bi flow when the oxygen concentration is low and the flow velocity is high. This phenomenon is not currently understood. The magnetite layer growth rate is limited by the iron diffusion in the oxide layer lattice. The Fe-Cr spinel layer grows in the nanometric cavities formed at the Fe-Cr spinel /T91 interface by the outwards diffusion of iron. Due to this mechanism the growth rate of the Fe-Cr spinel layer is linked to that of magnetite. A modelling of this mechanism is presented. The modelling is in agreement with the experimental data in the case of a high oxygen concentration. However, the calculated oxide scale thicknesses are systematically lower than the experimental values in the case of a low oxygen concentration when the iron diffusion only occurs via interstitials in the oxide scale. Consequently, the estimation of the iron diffusion coefficient, when diffusion occurs via interstitials, is not reliable. To have a better estimation of this iron diffusion coefficient in the Fe-Cr spinel, when diffusion occurs via interstitials, a fit is done using experimental data coming from the European DEMETRA project. Although this evaluation is only based on a fit on the experimental data, it permits to estimate the oxide layer growth kinetics in case of the formation of the described duplex oxide layer, for each oxygen concentration (leading to a vacancy and/or an interstitial diffusion), each temperature between 450 and 620 °C and each hydrodynamic flow. This model shows that the hydrodynamic flow affects the corrosion rate only by the removal of the upper magnetite layer leading to an increase of the oxygen concentration at the spinel/magnetite interface. The oxidation mechanism is thus neither changed by the Pb-Bi flow nor by the oxygen concentration. However, the oxygen concentration modifies the iron diffusion process in the oxide lattice. DEWEY : 620.1 ISSN : 0947-5117 En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.201005871/abstract [article] Modelling of the oxide scale formation on Fe-Cr steel during exposure in liquid lead-bismuth eutectic in the 450–600 °C temperature range [texte imprimé] / L. Martinelli, Auteur ; F. Balbaud-Célérier, Auteur . - 2011 . - pp. 531–542. Génie Mécanique Langues : Anglais (eng) in Materials and corrosion > Vol. 62 N° 6 (Juin 2011) . - pp. 531–542 Mots-clés : Fe-Cr  Magnetite,  Spinel  Oxidation  mechanism  Pb-Bi Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Previous studies showed that the oxidation of T91 (Fe-9Cr martensitic steel) in liquid Pb-Bi eutectic leads to the formation of a duplex oxide layer containing an inner Fe2.3Cr0.7O4 spinel layer and an upper magnetite layer. The magnetite layer is easily removed by the Pb-Bi flow when the oxygen concentration is low and the flow velocity is high. This phenomenon is not currently understood. The magnetite layer growth rate is limited by the iron diffusion in the oxide layer lattice. The Fe-Cr spinel layer grows in the nanometric cavities formed at the Fe-Cr spinel /T91 interface by the outwards diffusion of iron. Due to this mechanism the growth rate of the Fe-Cr spinel layer is linked to that of magnetite. A modelling of this mechanism is presented. The modelling is in agreement with the experimental data in the case of a high oxygen concentration. However, the calculated oxide scale thicknesses are systematically lower than the experimental values in the case of a low oxygen concentration when the iron diffusion only occurs via interstitials in the oxide scale. Consequently, the estimation of the iron diffusion coefficient, when diffusion occurs via interstitials, is not reliable. To have a better estimation of this iron diffusion coefficient in the Fe-Cr spinel, when diffusion occurs via interstitials, a fit is done using experimental data coming from the European DEMETRA project. Although this evaluation is only based on a fit on the experimental data, it permits to estimate the oxide layer growth kinetics in case of the formation of the described duplex oxide layer, for each oxygen concentration (leading to a vacancy and/or an interstitial diffusion), each temperature between 450 and 620 °C and each hydrodynamic flow. This model shows that the hydrodynamic flow affects the corrosion rate only by the removal of the upper magnetite layer leading to an increase of the oxygen concentration at the spinel/magnetite interface. The oxidation mechanism is thus neither changed by the Pb-Bi flow nor by the oxygen concentration. However, the oxygen concentration modifies the iron diffusion process in the oxide lattice. DEWEY : 620.1 ISSN : 0947-5117 En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.201005871/abstract