A comparative study of plastic deformation behaviors of OFHC copper based on crystal plasticity models in conjunction with phenomenological and dislocation density-based hardening laws

摘要

An innovative crystal plasticity model was developed by incorporating the dislocation density-based hardening law, in which the grain-level hardening behavior is dependent on the evolution of the dislocation density in the cell walls and cell interiors and the evolution of the volume fraction of the cell walls. The large plastic deformations of OFHC copper single crystals and polycrystals were simulated by the two crystal plasticity models in conjunction with the dislocation density-based hardening law and the classic saturation-type phenomenological hardening law, respectively. A comprehensive comparison study on the 2 hardening laws was accordingly carried out in terms of the stress-strain responses and texture evolutions. The simulation results of the two crystal plasticity models conjuncted with the different hardening laws have a good consistency, and both of them are generally in good agreement with the experimental data, which therefore validate the developed crystal plasticity model incorporated with the dislocation density-based hardening law. The Taylor-type mean-field model and Voronoi-type full-field model were, respectively, used as the homogenization schemes to calculate the macroscopic stress-strain responses of the polycrystalline aggregate, and the two kinds of calculated results were compared and analyzed in detail. By using the Taylor-type mean-field crystal plasticity finite element method (CPFEM), the processes of single shot impact along the different impact angles were numerically simulated; the macroscopic plastic deformations, microscopic texture evolutions and dislocation density evolutions were resultantly investigated, which would conduce to the further study on the microscopic strengthening mechanisms of shot peening or surface mechanical attrition treatment, and the rise of the new ideas for relevant modeling.