Modes of Grain Selection in Spiral Selector during Directional Solidification of Nickel-base Superalloys

The modes of grain selection in spiral selector were investigated by both a ProCAST simulation and experimental confirmation. The results show that the efficiency of grain selection in starter block is associated with the geometry shape. At the early stage of grain selection, the optimization of grain orientation is dominated by competitive grain growth, but the optimization of grain orientation in starter block is gradually dominated by geometry shape at the later stage of grain selection. Besides, the spiral part could also optimize the orientation of the selected single crystal when the initial angle is large enough, and the single crystal selection in spiral parts with different pitch lengths and initial angles is dominated by different modes. The simulation results agree well with experimental ones.