Numerical Simulation for Microstructure Evolution in In718 Alloy During Cylindrical Cup Backward Extrusion

A coupled numerical simulation between thermal-mechanical and microstructure evolution was realized through embedding the developed user subroutines into the FEM software DEFORM-3D system. Then the dynamic recrystallization fraction and average grain size of In718 alloy in cylindrical cup backward extrusion with different parameters was solved and analyzed. The complete dynamic recrystallization occurs in the middle of cylinder wall and the grain size is the finest. However, the grain size of top of cylinder wall changes less because of the less plastic deformation. Furthermore, higher speed of punch is useful to the DRX but it is not enough time to occur dynamic recrystallization completely with much higher speed of punch. In spite of more recrystallization occurring in the bottom, the grains grow in the cylinder wall so that much higher temperature goes against improving finer and uniform of grain size. Therefore, it is better for obtaining finer and uniform grain size with 1000(°C)-1050(°C) and 5(mm/s) in In718 alloy cylindrical cup backward extrusion according to the research.