Creep behavior of a directionally solidified nickel based superalloy

Abstract

Directionally solidified nickel-base superalloys provide significant improvements relative to the limitations inherent to equiaxed materials in the areas of creep resistance, oxidation, and low and high cycle fatigue resistance. The objectives of this study are to perform critical experiments and investigate the high temperature creep deformation, creep rupture and creep crack growth behavior of DS GTD111. The specimens in the longitudinal direction showed higher creep ductility, lower minimum strain rates and longer creep rupture times than the specimens in the transverse direction. The results in the transverse direction were similar to the ones for the equiaxed version of this superalloy A power-law model and the theta-projection model is evaluated for representing the material behavior and both appear to provide accurate representations of creep deformation over a wide range of stress, time and temperature conditions. The Monkman–Grant relationship, the Larson–Miller parameter and the theta projection model have been successfully used to predict the time to rupture for different orientation-temperature-stress conditions. The time dependent fracture mechanics approach is used to model creep crack growth behavior.