Simulation of grain selection during single crystal casting of a Ni-base superalloy

The grain selection process during single crystal casting of a Ni-base superalloy DD403 in spiral grain selector is simulated by a macro-scale ProCAST coupled a meso-scale Cellular Automaton Finite Element (CAFE) model. And the simulation results are validated by experimental observations. It is found that the grain orientations can be optimized in starter block and the length of starter block could be reduced to about 26.0 mm. A single crystal can be rapidly selected after the solidification front climbing 400° along the spiral passage. It is proposed that the coupling effect of the heat flow direction, the preferred growth direction and the geometrical restriction of spiral wall makes contribution to the crystal selection in spiral passage. An investigation into the grain orientation selection in grain selectors with different geometries reveals that crystal orientation can be optimized by increasing the length of starter block or decreasing its width. However, no obvious relationship is found between the crystal orientation and the parameters of spiral passage.