INVESTIGATION OF THE STRESS CORROSION CRACKING OF CARBON STEEL IN FUEL GRADE ETHANOL ENVIRONMENTS

Recently, there has been much evidence of the phenomenon of stress corrosion cracking (SCC) in carbon steel equipment in the ethanol industry. Research shows the effects of simulated fuel grade ethanol (SFGE) composition on SCC severity in carbon steel. To evaluate the effect of chloride on SCC of carbon steel in SFGE, notched X60 carbon steel samples were tested using slow strain rate test (SSRT) in commercial fuel grade ethanol (FGE) with and without dissolved chlorides. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were used to characterize steel fracture surfaces, and capillary ion electrophoresis (CIE) and Karl Fischer titration (KF) to characterize compositional changes in FGE environments. Results showed that as chloride content increased in SFGE, SCC susceptibility increased. In FGE, SCC was not found in the absence of added-chlorides, but was severe when chlorides were present in the notched area of the sample during constant extension rate tests (CERT).