Superalloy turbine blade is made by directional solidification process. To make the turbine blade of needed properties, the control of microstructure and defect in directional solidification process is very important. But it is very difficult to find out the details of solidification characteristics in experiment, so computer simulation is indispensable.
In directional solidification process, important process parameters are withdrawal speed and furnace temperature, and important solidification variables which affect the casting microstructure and defect are the shape of solid/liquid interface, solidification rate and temperature gradient. Different process parameters result in different solidification variables, so finally results in different microstructure and defect.
The objective of this research is to find out the effect of process parameters on the solidification variables by the numerical analysis of the directional solidification. To do this, two castings were analyzed with commercial FEM package, ANSYS. First, a rod-shape casting without any cross-sectional area change was calculated. This calculation results were compared with the experimental results and those two results were in good agreement. But in this simple rod shape casting, solidification rate and temperature gradient values were almost uniform during the solidification. So to find out the solidification phenomenon in complex rod shape casting like turbine blade, a casting with cross-sectional area change was modeled and calculated. From this calculation, the effect of process parameters on the microstructure and defect of casting were predicted.
