Creep residual life prediction of a nickel-based single crystal superalloy based on microstructure evolution

Abstract

Microstructure evolution occurs throughout the high temperature creep process inside nickel-based single crystal superalloys. In this study, creep tests of a nickel-based single crystal superalloy in the [001] orientation at 980 °C and 1100 °C were performed. The results indicated that creep failure occurred due to the formation of micropores and deterioration. Scanning electron microscopy (SEM) observations showed that the material degradation during creep was primarily reflected in the coarsening of the matrix channel and the precipitation of the TCP phase. Meanwhile, transmission electron microscopy (TEM) observations indicated that the dislocation morphology of the [001] orientation is consistent with the characteristics of the octahedral slip system. To obtain a quantifying explanation of such microscopic phenomena, a material constitutive model and creep damage model considering the Orowan effect and the dislocation effect were established based on the crystal plasticity theory. The model parameters were fitted according to the experimental results. Based on the quantitative description of the microstructure evolution during the creep process, the residual life prediction model of a single crystal superalloy was established for guidance in engineering applications.