Dislocation density-based modeling of deformation behavior of aluminium under equal channel angular pressing

In this study, the deformation behavior of aluminium during equal channel angular pressing (ECAP) was calculated on the basis of a dislocation density-based model. The behavior of the material under ECAP, including the dislocation density and cell size evolution as well as texture development, was simulated using the finite element method (FEM). The simulated stress, strain and cell size were compared with the experimental data, which were obtained by ECAP for several passes in a modified Route C regime. Good agreement between simulation results and experimental data, including strain distribution, dislocation density and cell size evolution, strain hardening and texture development was obtained. As concerns the general trends, the stress was found to increase rapidly in the first ECAP pass, the strain-hardening rate then dropping from the second pass on. Calculations showed a non-uniform strain distribution evolving in the course of ECAP. The simulated cell size is also in good agreement with the experiment, particularly with the observed rapid decrease of the cell size during the first pass slowing down from the second pass onwards. Larger cells were found to form in the upper and the lower parts of the workpiece where the strain is smaller than in the middle part. Due to the accumulation of strain throughout the workpiece and an overall trend to saturation of the cell size, a decrease of the difference in cell size with the number of passes was predicted.