Anisotropy And Non-uniformity Of The Plastic Deformation For Polycrystalline Metal

Crystalline engineering materials mostly occur in polycrystalline forms. The main characters of plastic deformation are anisotropy and non-uniformity. Single crystal exhibits a strong plastic anisotropy due to crystallographic glide on a discrete set of slip directions. Anisotropy in polycrystals resulting from moderately large strains is caused primarily by the reorientation of grains into preferred orientations. The heterogeneous deformation behaviour observed within grains in a polycrystal is attributed to microstructural features such as grain structure, topology, size, etc. Consequently, quantitative prediction of anisotropy and heterogeneity during plastic deformation processes will play an important role in theoretical research and practical manufacturing. In this paper, the anisotropy and heterogeneity during plastic deformation of polycrystalline material were simulated using the crystal plasticity model.In the simulation of the longitudinal anisotropic behavior of the axisymmetry deformation texture for polycrystalline copper, the polycrystalline copper was stretched along an arbitrary direction after it had undergone axisymmetry deformation. Longitudinal anisotropy and transversal isotropy of the axisymmetry deformation of polycrystal were analyzed. The contours of elastic module and flow stress in three-dimensional orientation space were given and analyzed. The evolutions of elastic module and flow stress in some planes and some directions were also analyzed. According to the results, during of the axisymmetry deformation, longitudinal anisotropy and transversal isotropy of polycrystal were obvious with the effective strain increasing.In the simulation of heterogeneity of coarse-grained polycrystal under uniaxial tensin, the true strain and the true stess in the grain interiors and around grain boundaries were analyzed. Activated slip systems in the plastic deformation were quantitative predicted according to the shear strain along different slip systems. It was found that both intergranular and intragranular plastic deformation fields were highly heterogeneous. Grains with soft orientations were likely to experience more plastic deformation than grains with hard orientations. The activated slip systems were different with grains. There were two or three activated three slip systems in each grain, and at most two were primary. Intergranular deformation was subordinate in plastic deformation of polycrystalline material.