Control of Edge Plate Stray Grain of Single-Crystal Turbine Blade by Using Process Bar Method

Single-crystal (SX) turbine blade is the key component for aero-engines. However, the quality of the SX turbine blade is limited by the stray grain defects. When the structure and material are determined, in order to eliminate this defect, the process bar method is used to control the formation of stray grain. However, the structure of process bar is not researched. Generally, the process bar is designed by experience. In this paper, the simulation method is used to design the process bar structure. In order to describe the stray grain features, the critical stray grain cooling rate is put forward to predict the stray grain defect. With the help of the CAE analysis, the process bar dimension and position are determined by this method for a sample turbine blade. The result shows the process bar could modify the shape of the solidification interface and control the stray grain defect. Meanwhile, it also could control the dimension of the platform. And then, the effectiveness of this process bar design method is confirmed in the sample turbine blade experiment. The experiment result illustrated that the stray grain was eliminated.