3D-FE Simulation Of Equal Channel Angular Pressing Of Ti-6Al-4V Alloy

Equal channel angular pressing (ECAP) method as a severe plastic deformation (SPD)technology of metals, grains of the deformed materials are greatly to micrometer size or evento nanometer size, it can result in the increased strength at the same time remained ductility ofmaterials. ECAP is an effective way to obtain the large bulk ultrafine grained (UFG) materials,so it has a good prospect for industrial applications. In this paper, a series of ECAP finiteelement models of Ti-6Al-4V alloy in different parameters are constructed by using the finiteelement software DEFORM-3D. And the behavior of deformation in the ECAP process ofTi-6Al-4V alloy sample is simulated and analyzed. In order to research the effect of differentparameters such as temperatures, friction, mold geometry factors and deformation velocity tograin refinement, and to obtain the optimum size of grain in simulation, so as to provide atheoretic guide for making practical technology.According to the load-time curve obtained during the simulation in the followingparameters: internal corner angle of120o, outside corner angle of37o, friction coefficient of0.1, temperature of920℃, deformation speed of3mm/s. The deformation process of ECAPcan be divided into four stages: initial stage, transition stage, steady stage and final stage.Steady stage is the main one among four stage, during which severe shear deformationsteadily and continuously occurs so that the load remains as a constant. When the process isfinished, a steady zone with a larger equivalent strain is gained in the center section of thesample.The simulation results at different temperatures (860℃、890℃、920℃、950℃) show asthe temperature increases during the extrusion forming process, the load during the process isdecreasing, shear deformation occurs more easily, But it is not good for the grain refinementin the high temperature.The simulation results under the condition of different outside corner angles (0o、37o、60o)show that the larger outside corner angle is the less hindrance the metal encounters.Furthermore, with the increase of outside corner angle, the load needed in the process ofECAP and the uniform deformation region of the sample decrease and the inhomogeneity ofequivalent strain increases.The simulation results under the different friction coefficient (0.05、0.1、0.2) show that asthe friction coefficient increases, the equivalent strain accumulated during the process is growing. The extent of inhomogeneous deformation in the sample increases in case of frictionand the load in the process is extremely large compared. Friction is extremely unfavorablefactors。...