Simulation Of Inhomogeneous Slip Deformation In FCC Metals With Textured Polycrystal Plasticity Finite Element

With equal-angle-distance discretization of the orientations in the four-dimension orientation space and the particle swarm optimization (PSO) texture decomposition components based orientation discretization method proposed, the textured polycrystal plasticity finite element (TPCPFE) model is established in the present dissertation. The influences of inter- and intra- granular inhomogeneous deformation on the development of rolling textures of FCC metals are systematically and quantitatively investigated. The mean value θ_m of the disorientation between the discretized points and the corresponding granular average orientation is used as the parameter for the characterization of inhomogeneous deformation in the meso-scale. And the inhomogeneous deformation in the meso-scale under plain strain compression (PSC) due to orientation gradient and grain boundary is investigated with TPCPFE. The PSO method is introduced into the quantitative texture decomposing and the texture computational optimization for analysis of the plasticity anisotropy, which introduces a more precise algorithm for texture analysis. The following results can be concluded:(i) The quantitative texture decomposition and true orientation distribution function (ODF) calculation with the PSO method is more precise and more effective than the traditional method. By contrasting PSO with Nelder-Mead Simplex (NMS) algorithm, it shows that for the composed textures with simple textured components the same results calculated are obtained with both methods. However, for complicated textures the NMS will easily fall into local minimum which will lead to error in quantitative texture decomposing. Thus the PSO method is more suitable for actual complicated quantitative texture analysis.(ii) The parameter of θ_m for characterization of the inhomogeneous deformation in the meso-scale can avoid the error that comes from defocusing due to moving of the incident beam in the EBSD analysis. And together with the recrystallization theory, the parameter θ_mc which is critical value of θ_m can be used as a quantitative description of recrystallization in EBSD analysis of the partially recrystallized materials.(iii) By taking inter- and intra-granular inhomogeneous deformation into account, the TPCPFE model is more precise than the Sachs, FC and the modified models for simulation of rolling textures.(iv) With the TPCPFE simulation of the inhomogeneous deformation in the meso-scale, strengthening cube texture by meso-scale inhomogeneous deformation is proposed. And with simulation of the development of θ_m and the misoriention θ_rot between the average orientations before and after deformation, the inhomogeneous plasticity flow behavior of cube texture is obtained in the...