The effect of salt composition on the stress-free and corrosion-fatigue performance of a fine-grained nickel-based superalloy

This paper describes work to study hot corrosion damage in the nickel-based gas turbine alloy RR1000 coated with various salts at 600 °C. Interest in type-II hot corrosion on the fatigue resistance of gas turbine alloys has increased to minimise power/thermal inefficiencies. Stress-free corrosion demonstrated a greater impact of sulphate (versus chloride) on maximum pit depth, a key influencing factor of fatigue lives. In corrosion-fatigue testing, at low stresses sulphate was shown to be more influential of fatigue life. At high stresses, the presence of greater crack initiation sites, reduced initiation lives and cracked oxide suggests chlorine influenced the crack-initiation behaviour.