The Study On 3-D Finite Element Simulation And Experiment Method For ECAP

As untrafine-grained(UFG) materials show unique properties, such as high strength and superplasticity, a considerable interest has been concentrated on these special materials over the past few years, especially on the mechanical behavior and processing technology of materials. Equal channel angular pressing (ECAP) has been the subject of considerable research in recent years, because it is very effective in producing UFG structures and can produce UFG billets large enough for various structural applications.In this paper, a three dimensional finite element (3D-FEM) model is used to simulate the process of equal channel angular pressing. Equivalent plastic strains are compared in different friction conditions. It is found that the deformation varies along three directions, which indicates two dimensional finite element model is unable to properly simulate the deformation distribution during ECAP process. The influence of friction on equivalent plastic strain and pressure is also found remarkable. Deformation inhomogeneity indexes and the location of maximum equivalent plastic strain vary with increasing friction coefficient.3D-FEM models, which can simulate two continuous ECAP passes. were also used to analyze the deformation distribution of three pressing routes commonly using in producing UFG materials. The simulation results indicates that after two passes. the equivalent plastic strain distribution of 180° rotation route, which the samples was rotated 180° along its axes between two passes, is the most homogeneous. But from the view of deformation homogeneity, if one sample will be subjected to more than four passes, the 90° rotation route, which the samples was rotated 90° along its axes in same direction between two passes, is thought to be the most capable route to achieve homogeneous deformation.Besides the FEM simulation, two ECAP dies were designed to produce UFG copper. Although the tests were failed because of the defects of the dies. some experience and lesson are learnt from those unsuccessful experiments, which must be valuable to the future research.