Abstract:In order to reveal the temperature dependence of anisotropic stress−rupture behavior of SRR99 single crystal superalloys under conditions of temperature ranging from 650 to 1 040 °C and typical stresses, fracture morphologies and microstructure evolution were investigated by SEM and TEM. From the Larson-Miller curves, it is found that single crystal with [001] orientation has the optimum stress rupture property in comparison with [011] and [111] orientations at lower and intermediate temperature. With increasing temperature to 1 040 °C, stress−rupture properties of single crystals with three principal orientations tend to be equivalent. Based on the fracture surface and microstructural observations, superior stress−rupture behavior of single crystal with [001] orientation was rationalized and the effect of misorientation of single crystal on stress rupture property was also discussed.

Key words: single crystal superalloy; stress−rupture property; anisotropy; deformation mechanism