Corrosion resistance test of stainless steels in the biofuel environment

The oxidation degradation characteristics of four types of bioethanol fuel and one type of biodiesel fuel were investigated. It was found that rape methyl ester (RME) was the fuel that was most susceptive to oxidative degradation, whereas bioethanol fuels were resistant. Oxidative degradation of the fuels promoted the formation of fatty acids in the water phase. Once all formic and acetic acid contained in the oxidized RME was distributed in 0.1 vol% of the water phase, its pH was estimated to be ~1.6. Of the different stainless steel variants in the corrosion tests, which simulated the most severe conditions, SUS436L and SUS444 exhibited excellent corrosion resistance. © 2019 Society of Automotive Engineers of Japan, Inc.