The corrosion resistance of 316L stainless steel in 65 wt % ethanol, 35 wt % water, 1 wt % H 2 SO 4 solution containing different NaCl concentrations and at different temperatures was investigated using open circuit potential measurements, polarization curves, and electrochemical impedance spectroscopy. At 25 C, the minimum NaCl concentration required for occurrence of pitting was 0.58 wt %. In 0.35 wt % NaCl solution, localized corrosion was observed at temperatures higher than 40 C and, depending on the potential, metastable or stable pits were observed. No pits were observed below 40 C in 0.35 wt % NaCl solution. Stainless steels are used as construction materials for key corrosion-resistant equipment in most of the major industries, and especially in chemical, petroleum, processing, and power generation plants. A very thin film, known as the passive film, which is selfhealing in a wide variety of environments, 1-4 provides their corrosion resistance. Due to environmental concerns, there has recently been an increase in the demand for ethanol as a road vehicle fuel. There is therefore, a greater need for studies of the corrosion resistance of materials used in alcohol production plants, and in transportation and storage facilities.Among these stainless steels, the 300 series stands out. The 300 series represents compositional modifications of the classic 18=8 (18% Cr-8% Ni) stainless steel, which has been a popular corrosion-resistant material for some 70 years, to improve pitting, crevice and stress corrosion resistance, high-temperature oxidation resistance and strength, and reduce intergranular corrosion in welded materials. Type 304 is the general-purpose grade, widely used in applications requiring a good combination of corrosion resistance and formability. On the other hand, type 316 contains molybdenum and has greater resistance than type 304 to pitting in marine and chemical industry environments. and pitting corrosion constitutes one of the most important failure mechanisms. Pits cause failure through perforation, and engender stress corrosion cracks.1 Pitting corrosion has been studied for the last few decades and, according to Frankel,6 fundamental studies have focused on characterization of the passive film, the initial stages of passive film breakdown, metastable pitting growth, and the growth of large and stable pits.Solution chloride concentration is a very important parameter influencing pitting formation on stainless steels. Increasing the chloride concentration significantly increases the possibility of pitting. The chloride levels that can be tolerated without the onset of pitting increase with the chromium and molybdenum contents of austenitic and ferritic stainless steels (for example, the minimum chloride ion concentration in 1 mol L À1 H 2 SO 4 for initiation of pitting on pure Fe is 0.3 mmol L
À1, while on Fe-18.6Cr-9.9Ni alloy it is 0.1 mol L
À1).
1Electrochemical studies of pitting corrosion have found the existence characteristic potentials. Stable pits form at potentials noble to t...