Cross-scale simulation of grain refinement and microstructure evolution in orthogonal turning of polycrystalline copper based on the FEM and CA model

Polycrystalline copper shows great potential for manufacturing of MEMS and other microstructures. It tends to dynamic recrystallizing under severe plastic deformation machining, which often produces grain refinement, affecting surface hardness and properties. To better understand the grain refinement process in machining, model endeavor on macroscopic distribution of fine grains and specific microscopic dynamic recrystallization of grains are highly needed. In this study, grain refinement and crystal microstructure evolution of polycrystalline copper were simulated by combing the FEM and cellular automat methods. The macro prediction of material dislocation density and grain size is realized by integrating the material dislocation-based constitutive into orthogonal cutting FEM model through the user-defined subroutine. Then, the CA model with the input thermal-mechanical information come from the FEM results is adopted to simulate the microscopic microstructure evolution process. Finally, orthogonal turning experiment of polycrystalline copper was carried out, and thermal-field electron backscatter diffraction technique (EBSD) are used to investigate the grain size and crystal orientation. The study show that the integrating of FEM and cellular automat method is an effective approach to understand the microstructure evolution of polycrystalline copper in high-speed cutting process.