High temperature corrosion of Fe-Cr-(Mn/Si) alloys in CO2-H2O-SO2 gases

Model alloys Fe-9Cr, Fe-20Cr (wt.%) and these alloys doped with 2%Mn or 0.5%Si were exposed to Ar-20%CO2-20%H2O-(0, 0.5)%SO2 (vol.%) gas at 811 degrees C for up to 500 h. The Fe-9Cr and Fe-9Cr-2 Mn underwent breakaway oxidation in both gases. The Fe-9Cr-0.5Si developed Cr2O3 scale in sulphur-free gas, but entered breakaway in sulphur-bearing gas. The Fe-20Cr developed Cr2O3 scale, with the growth rate being reduced by SO2 addition. Addition of SO2 did not alter the already high corrosion resistance of Fe-20Cr-2Mn. The temperature dependence of sulphur effects is discussed in terms of interfacial adsorptions, by comparing their corrosion behaviour at 650 degrees C. (C) 2016 Elsevier Ltd. All rights reserved.