Effect of centrifugal casting process on mold filling and grain structure of K418B turbine guide

Abstract

Due to the complicated geometry and thin wall of the turbine guide, some casting defects such as misrun and coarse columnar grains are usually produced during the gravity investment casting process, which have a close relationship with the mold filling and melt solidification processes. In this study, the filling and solidification processes of K418B nickel-based superalloy turbine guide under centrifugal casting condition were studied by numerical simulation with ProCAST software, and the actual pouring experiment was carried out to verify the filling integrity and grain structure of the castings. The results show that the pouring temperature of 1540 °C and centrifugal velocity of 150 rpm were beneficial to the complete mold filling of the guide castings, and the misrun defects at the exhaust sides of the guide were completely eliminated. At the same time, under the action of centrifugal force field, the coarse columnar grains perpendicular to the exhaust sides of the guide vanes were replaced by the fine equiaxed grains, which might help for improving the comprehensive mechanical properties of K418B turbine guide.