Corrosion of martensitic stainless steel in ethanol-containing gasoline: Influence of contamination by chloride, H2O and acetic acid

Corrosion of stainless steel DIN 1.4035 (Fe-13%Cr) was studied in ethanol-containing gasoline mixtures as a function of H2O, chloride and acetic acid concentrations. H2O and Cl− are primary corrosion triggering factors in EtOH/gasoline mixtures. The critical water content depends on the EtOH/gasoline-ratio. Pitting corrosion occurred in EtOH/gasoline blends at extremely low chloride-concentrations, which did not lead to passivity breakdown in a purely aqueous solution. An increasing chloride-concentration accelerates pit propagation, with little influence on pit densities. On the other hand, higher concentrations of acetic acid lead to a larger attacked area, with minor influence on the pit propagation in depth.