Modeling and analysis of grain morphology effects on deformation response based on crystal plasticity finite element method

Abstract

In order to investigate the grain morphology effects on deformation response at macro‐ and micro‐scale in polycrystalline metal, a method considering grain size and shape effects is proposed based on the classical crystal plasticity finite element method in this paper. A grain morphology controlled polycrystalline geometry model consisting of grain shape models and grain size transition models is developed based on Voronoi diagram. Grain size effect is introduced into the classical crystal plasticity constitutive model quantitatively on the basis of Hall‐Petch type relationship. With the aid of the method, grain aggregate finite element meshes with different mean grain sizes are established to simulate the deformation response of polycrystalline pure copper. The predicted values of flow stresses show good agreement with experimental ones. Finally, a set of grain aggregate finite element meshes with same mean grain size but different grain distributions are developed to simulate the uniaxial tension processes of polycrystalline pure copper. The results shown that the effects of grain morphology on the macro‐scale deformation response are insignificant under a large number of grains with random morphology and orientation. When the grain distributions changes regularly along the x direction, the maximum decrease of flow stress data is 10 MPa.