The influence of simulated fuel-grade ethanol on fatigue crack propagation in pipeline and storagetank steels

This study presents an evaluation of fatigue crack propagation in three steels (A36, X52, and X70) in a simulated fuel-grade ethanol environment. A fracture mechanics testing approach was used to determine crack propagation rates as a function of the stress-intensity-factor amplitude ( Delta K). Results of this testing and the fracture analysis indicate that all three materials are susceptible to enhanced fatigue damage in fuel-grade ethanol environments. We show that the damage mechanism is attributed to susceptibility of each material to ethanol stress-corrosion cracking under fatigue loading conditions and propose a model for determining crack growth rates in ethanol fuel.