Effect of Oxygen on Ethanol Stress Corrosion Cracking Susceptibility: Part 1—Electrochemical Response and Cracking-Susceptible Potential Region Available to Purchase

It is known that dissolved oxygen promotes stress corrosion cracking (SCC) of carbon steel in fuel-grade ethanol. The effects of oxygen on ethanol SCC were investigated using controlled-potential tests in deaerated simulated fuel-grade ethanol (SFGE) with supporting electrolytes. The effects of applied anodic potentials and supporting electrolyte on the electrochemical response of steel were investigated using micro-electrodes. The cracking susceptibility was reproduced in potentiostatic slow strain rate (SSR) tests in the absence of dissolved oxygen. Under potential control, SCC only occurs in a specific potential region, roughly −50 mV vs. saturated calomel electrode (SCE) ~ 300 mV_SCE. The cracking susceptibility is well characterized by secondary cracks on the necked section of the SSR samples and brittle attack along the perimeter of fracture surface. No evidence was found for the presence of ethanol oxidation products, which had been hypothesized to be responsible for the cracking susceptibility.