Anomaloustemperaturedependence ofoxidationkineticsduringsteamoxidation offerriticsteelsinthetemperature range550–650 °C J. _ Zurek a, * ,E.Wessel a ,L.Niewolak a ,F.Schmitz b , T.-U.Kern b ,L.Singheiser a ,W.J.Quadakkers a a Forschungszentrum J€ ulich GmbH, IWV-2, 52425 J€ ulich, FRG b Siemens Power Generation, M€ ulheim, FRG Received6August2003;accepted16January2004 Availableonline12March2004 Abstract Theoxidationbehaviorofanumberofselectedferriticsteelsinasimulatedsteamenvi- ronmentattemperaturesbetween550and650 °Cwasstudied.Intheprevailingtestgas,some ofthestudied9–12%Crsteelstendedtoexhibitananomaloustemperaturedependenceofthe oxidation behavior. This means, that the oxidation rates do not steadily increase with increasingtemperature.Athighertemperatures,someofthestudiedsteelstendtoformavery thinandprotectiveoxidescalewhereasatlowertemperaturerapidlygrowing,less-protective oxidesarebeingdeveloped.Theanomaloustemperaturedependenceisrelatedtodifferencesin chromiumdistributionintheinnerpartoftheoxidescale.Theeffectisobservedforsteelswith intermediate-Cr contents (10–12%) whereas steels with either lower or higher Cr contents exhibitanincreasingoxidationratewithincreasingtemperature. Ó 2004ElsevierLtd.Allrightsreserved. Keywords: A.Steel;B.SIMS;C.Hightemperaturecorrosion;Selectiveoxidation * Correspondingauthor.Tel.:+48-2461-61-55-22;fax:+48-2461-61-36-99. E-mail address: j.zurek@fz-juelich.de (J. _ Zurek). 0010-938X/$-seefrontmatter Ó 2004ElsevierLtd.Allrightsreserved. doi:10.1016/j.corsci.2004.01.010 www.elsevier.com/locate/corsci CorrosionScience46(2004)2301–2317