Channel Angular Extrusion Process Of Deformation Behavior

It is now established that equal channel angular pressing provides the capability of producing an ultra-fine grain size, in submicrometer or nanometer range, in many large-grained polycrystalline samples. The shearing associated with equal channel angular pressing was examined using optical microscopy. Samples of commercial pure Al with a large grain size were subjected to equal channel angular pressing to different strains and then examined on three orthogonal planes. Samples were pressed without any rotation or with rotations of either 90?or 180?deg between each consecutive pressing. The experimental observations are compared with models, which predict the shearing characteristics associated with equal channel angular pressing under different conditions. It is demonstrated that there is good agreement, in term of both the grain elongation and shearing within individual grains, between the experimental results and the predictions of the models.The Properties of the materials are strongly dependent on the shear plastic deformation behavior during equal channel angular pressing, which is controlled mainly by die geometry, materials properties and processing conditions, hi this study, the plastic deformation behavior of materials during the ECAP process with a round die corner angle (120? was investigated using the commercial two-dimensional rigid-plastic finite element code (DEFORM2D). The ECAP process was explained using five steps based on the calculated load curve (fast increase, slow increase, fast increase, steady and finally decreasing stages). The inhomogeneous strain distribution within the workpiece was analyzed by subdividing the workpiece into a front transient zone, an end transient zone, an outer less sheared zone, and the remaining shearing deformation zone. Due to the faster flow of outer part compared with the inner part within main deforming zone, the lesser shear zone hi the outer part of the workpiece occurs. The inhomogeneity of deformation occurs using a free friction between the samples and die. If using a angular die, the homogeneity of deformation will be enhanced.