A unified physically based crystal plasticity model for FCC metals over a wide range of temperatures and strain rates

摘要

A unified physically based crystal plasticity model for FCC crystalline materials is developed. This statistical dislocation dynamics based model considers the cellular dislocation substructures, in terms of three distinct dislocation densities, i.e., mobile dislocation density, immobile dislocation densities in cell walls (CWs) and cell interiors (CIs).The generation, trapping, immobilization and annihilation of dislocations on the slip system level are taken as the basis for evolution of three dislocation categories. Both the thermally activated cross-slip and rate controlling climb are viewed as the essential recovery mechanisms, to improve the prediction ability of the model over a wide range of temperatures. The model is applied to the hot compression simulations of polycrystalline pure copper. The predicted stress-strain curves fit the experimental data very well at the temperatures of 373 K to 573 K and strain rates of 0.01 s~(-1) to 1 s~(-1). Furthermore, the proposed model has only a single set of parameters, which are almost unrelated to the deformation conditions, so that the determination of parameters is less dependent on the fitting of experimental data. Such physically based model can more easily be used in the prediction of plastic deformation processes under conditions without available experimental data.