High temperature corrosion of valve steels in combustion gases of petrol containing ethanol addition

The corrosion of four valve steels (X33CrNiMn23-8, X50CrMnNiNbN21-9, X53CrMnNiN20-8 and X55CrMnNiN20-8) in combustion gases of petrol, containing different concentrations of ethanol (5, 10 and 50 wt.%) has been studied at 900 °C under thermal cycle conditions. It has been shown that the chemical composition, in particular chromium content, determines the corrosion resistance of these materials. The X33CrNiMn23-8 steel containing the highest chromium concentration does not virtually undergo corrosion, because of the formation of protective chromia scale. On the other hand, three remaining steels with lower chromium concentration undergo high temperature corrosion due to formation of heterogeneous scale with worse protective properties.