Influence of temperature on the R-effect for the fatigue crack growth of
nickel-base superalloy GH4169
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 examined 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.