Crystal Plasticity Simulation of Grain Size Effect on Deformation Behavior in Face Center Cubic Polycrystal

Abstract

A improved method is developed to model the effect of grain size on deformation behavior in polycrystalline pure copper. In this method, a grain size controlled polycrystalline geometry model based on the Voronoi tessellation is employed to generate virtual grain structures that are statistically equivalent to metallographic measurements in terms of grain size distributions, and a crystal plasticity constitutive model considering size effect is proposed on the basis of Hall-Petch type relationship. Then, a set of crystal plasticity finite element models are developed to simulate the tension flow stresses of polycrystalline pure copper with different mean grain size. The results show that the size constants τ0', k1, τs', k2 and ns in the crystal plasticity constitutive model are determined as 13.754, 65.584, 152.653, −4.820 and 0.418, respectively, and the simulated data of flow stresses show good agreement with experimental ones. In comparison with the classical method, the shear strain distributions and the differences of their ranges are remarkable, and more local shear strain concentrations can be observed in the transition zones between the larger grains and the smaller ones, when the improved method is applied.