Finite Element Simulation Of CP-Ti During Equal Channel Angular Processing At Room Temperature

Equal Channel Angular Processing is an effective method to process ultra-fine materials, by which various kinds of ultra-fine metal materials are done successfully. The application of commercial pure Titanium is restricted due to its low strength. As a result, there is an important meaning for academic research and practical use to fabricate high strength ultra-fine-grained pure Titanium material by ECAP and research relative basic theory.Finite Element Method provides a new way for ECAP, by which new technology is simulated to analyze the rules of metal move and change of strain and stress, deformation conditions, technologic parameters etc. this paper simulated the ECAP process of commercial pure Titanium and carried out relative experiments, which includes the distribution of stress and strain and change of extrusion loads under the condition of different die and technologic parameters, so that it can provide effective academic foundation for the design of die and actual experiments.The research observes that the foursquare meshes on the surfaces of workpiece change to parallelogram after ECAP, which are demonstrated by the actual experiment and simulation at the same time. Simulation research shows that the whole workpiece can be divided three parts: non-deformation and small deformation part at the fore, even deformation part in the middle, non-deformation part at the end. The changes of extrusion force during ECAP include the linear going-up stage, yielding stage, the second going-up stage, steady-going stage, and going-down stage as well. When being not outer curvature angle and inter curvature angle at the cross of the two channels, the workpiece deforms unevenly and the maximum equivalent strain exists the underneath surface of the workpiece. For the die with the angle 90° between the two channels and the outer curvature angle 20°, when the radius of inter curvature angle changes from 0mm to 2mm, the workpiece deforms more evenly and equivalent strain is biggest at the 0.5mm radius of inter curvature angle. For the die with the angle 120° between the two channels, when the outer curvature angle changes from 0° to 60°, the deformation of workpiece is the most even and severe at the 20° outer curvature angle. When the angle between the channels varies from 90° to 120° and the outer curvature angle is changeless at 20°, the equivalent strain distribute more even and the maximum equivalent strain and extrusion load decrease with the increase of the angle between the channels. The workpiece deforms more uneven and the maximum pressing force enhaneces when the friction coefficient goes up. The deformation of workpiece is more uneven and the maximum equivalent strain and extrusion load increase when the pressing velocity goes up.