Simulation of Creep in Nickel Based Single Crystal Superalloy

Studeent: Yunhong Pang

Advisor: Dr. I.J Rao

ABASTRACT

Nickel based single crystal superalloys are finding wide spread use in high temperature gas turbines and other similar applicants because of their superior high-temperature strength and creep properties as compared to the other materials. This is due to two factors: solid solution and precipitation strengthening of the gamma and gamma prime phases, and the elimination of grain boundaries.

This research is focused on developing a continuum model to simulate the creep response of Nickel based single crystal superalloys that includes the influence of stress, temperature and orientations. A framework, built on the idea of evolution of nature configurations, utilizing the maximization of the rate of dissipation, has been used to formulate the model.

The main material parameters required to solve the equations are the components of the viscosity tensor, K. A parametric study is required to decide the viscosity tensor K.. Anisotropic property is also taken into account by introducing a fourth order tensor.

Two types of constitutive equation are obtained for high and low temperature separately. Simulation results, creep curves and strain vs. strain rate curve, also clearly indicate the difference between the low and high temperature regimes.