Development of Numerical Simulation in Nickel-Based Superalloy Turbine Blade Directional Solidification

Ni-based superalloy turbine blades have been widely used in aerospace and industrial engine. Numerical simulation techniques can optimize the superalloy directional solidification process and enhance the rate of finished products. This paper summarized the existing macroscopic and microscopic numerical models in the superalloy blade directional solidification process. Simulations have been done on the temperature field evolution, grain structure and dendrite morphology in typical HRS and LMC directional solidification conditions, and the resulting microstructure features were investigated. In particular, the application of varying withdrawal rate in directional solidification of the superalloy blade was introduced. And the advantages of the varying withdrawal rate technique were emphasized by comparing it with the constant withdrawal rate method. The simulation results indicate that by applying varying withdrawal rate, the convex or concave shape of the mushy zone can be change to flat shape, so that parallel columnar grains can be obtained with enhanced high-temperature performance of the turbine blade.