Comparative assessment of the degradation mechanism of micro-alloyed steel in E20 and E80 simulated fuel grade ethanol environments

In this study, micro-alloyed steel (MAS) material normally used in the production of autoparts was immersed in gasoline (as a reference), E20 and E80 simulated fuel grade ethanol (SFGE) environment and its degradation mechanism was evaluated. Investigation of corrosion behaviour through mass loss tests and electrochemical measurements showed that no mass loss was recorded for tests in gasoline whereas lowest corrosion rate values were found in E20 and the highest values in E80. Post-corrosion SEM images of the samples after immersion tests showed degradation of MAS in E20 by crevice and pitting corrosion. On the other hand, MAS deteriorated in E80 by uniform corrosion. The presence of water and dissolved chlorides in E20 stimulated pit initiation and growth on MAS. Corrosion degradation of MAS is dependent on ethanol concentration within the tested range of 20 to 80 % ethanol.