Directional solidification behavior of turbine blades in DZ125 alloy:design of blade numbers on assembly

The influence of blades assembly,i.e.,the blade number on the solidification process,heat exchange and grain structure on a directionally solidified Ni-based superalloy DZ125 was investigated by combining the experimental and simulation results.The casting process was simulated thermodynamically by ProCAST software,where the interface heat transfer coefficient was precisely determined by a measurement with thermocouples.There is a good agreement between experimental and simulation results.It was interestingly found that with the number of blades increasing from 6 to 10,due to the decrease in radiation absorption efficiency,the maximum temperature and the heating rate decrease in the mold,during the preheat process.During the withdrawal procedure,increased assembly numbers reduce the radiation exchange from mold to the enclosure,resulting in the decrease in cooling rate and temperature gradient of the blades.At the end of withdrawal,the slower cooling rate of the outside balances the temperature distribution of internal and external surfaces on the rabbet of blade.