Numerical simulation and experimental verification of gravity and centrifugal investment casting low pressure turbine blades for high Nb–TiAl alloy

Abstract

Gravity and centrifugal investment casting processes of low-pressure turbine blades with high Nb–TiAl alloy were simulated by Procast software. Actual blade components were poured by vacuum induction suspended furnace with Ar protection. The experimental verification indicated that the simulation results were in good agreement with the experimental results. Comparative results had shown that the surface of centrifugal casting blade was more complete than that of gravity casting one. In gravity casting process, molten metal filled the thinnest trailing edge at last, resulting in the generation of misrun defects. Furthermore, the shrinkage porosity and crack defects of gravity casting were much more and dispersive. The internal and external quality of centrifugal casting was much better than that of gravity casting. Microstructures from edge to center of gravity casting blade had no significant change. The microstructure for centrifugal casting blade is finer than that for gravity casting blade, however, a large number of dentritic γ segregation appeared in the blade edge of centrifugal casting, which resulted from the fast cooling rate of centrifugal casting surface.