Influence of temperature on the R‐effect for the fatigue crack growth of nickel‐base superalloy GH4169

Abstract The stress ratio ( R ) effect, especially at elevated temperatures, is associated with the fatigue crack growth (FCG) prediction in aero‐engine hot‐end components under complex operation conditions. The FCG experiments with three R were conducted on Ni‐based superalloy GH4169 at room temperature (RT), 550°C, and 700°C. The results indicate that the R‐effect on the FCG of GH4196 is temperature‐dependent. Therefore, efforts were made to identify the R‐effect at various temperatures to describe the FCG. The concept of the crack‐closure or the two‐driving‐force was employed to quantify the R‐effect considering the temperature influence. Fractographic analyses on the fracture surface were performed to discuss the underlying mechanism responsible for the temperature influence. The study can contribute to the R‐dependent FCG modeling at various temperatures.