0000000000637254
AUTHOR
Olivier Delrue
Influence de la composition chimique du film passif et des contraintes résiduelles sur le comportement micro-électrochimique des aciers inoxydables duplex en milieux contenant des ions chlorure
Le comportement micro-electrochimique d’aciers inoxydables duplex a ete determine dans des milieux contenant des chlorures, a l’aide de la technique de la microcellule electrochimique (capillaires de 30 µ m). Les resultats obtenus ont ete analyses en considerant la composition chimique du film passif. Des relations quantitatives entre les parametres electrochimiques et la distribution en chrome et fer dans la couche passive ont ete trouvees. Comme les deux phases ont des proprietes mecaniques differentes, un champ de contraintes residuelles heterogene est genere a la surface de l’alliage. Une methode thermo-mecanique basee sur la simulation numerique par elements finis a ete utilisee pour c…
Influence of the passive film properties and residual stresses on the micro-electrochemical behavior of duplex stainless steels
In the present paper, the chemical composition of passive films formed on both phases of two types of duplex stainless steels (UNS S31803 and UNS S32304) is determined at the micro-scale using Auger electron spectroscopy (AES). Samples were either mechanically polished (down to diamond pastes) or electrochemically etched in acidic solutions. The micro-electrochemical behavior of samples was then determined in sodium chloride media by means of the electrochemical micro-cell technique (capillary diameters of 30 μm). The results obtained were analyzed considering the passive film chemical composition. Quantitative relationships between electrochemical parameters and the distribution of chromiu…
Influence of long-term ageing in solution containing chloride ions on the passivity and the corrosion resistance of duplex stainless steels
Abstract The influence of long-term ageing in NaCl on the passivity and the electrochemical behavior of UNS S32304 is studied. The passive film thickness, the Cr/Fe ratio and the chloride content were significantly increased after ageing. The chloride distribution depends on residual stresses, sample microstructure and surface preparation. Local electrochemical measurements revealed that pitting potentials are between 250–550 mV vs. SCE after electropolishing. The higher the chloride content, the lower the local pitting potential. It was also shown that the presence of chloride was balanced by the enrichment in chromium after ageing. Then no pitting potential could be measured.