NUMERICAL SIMULATION OF RECRYSTALLIZATION PROCESS OF NICKEL BASE SINGLE CRYSTAL SUPERALLOY

The formation of recrystallization can cause great damage on the performance of nickel base single crystal superalloy turbine blade. The stress, strain and stored energy distribution of single crystal superalloy were modeled and simulated under the condition of inhomogeneous deformation. The critical stored energy was established which takes the anisotropic mechanical properties of single crystal superalloy and the recrystallization grain boundary migration process into account. Based on the calculation of the critical stored energy, the recrystallization microstructure in the local deformation zone after heat treatment was simulated by using cellular automaton (CA) method. DD6 single crystal test bars were treated by the cold deformation process and then annealed at the temperature of 1280 C for 30, 60 and 240 min. The experimental results showed that the recrystallization occurred on the surface near the deformation area. The recrystallizaton area and the grain size increased gradually with time. The simulated microstructure results agree well with the experimental ones (EBSD) and indicate that the recrystallization process of single crystal superalloy can be well simulated by the proposed model.