Three-Dimensional FE Simulation of Multi-strokes Pilgering Cold Roll of TA18 Titanium Alloy Tube: II Analysis of Plastic Deformation Behavior

Using the established three-dimensional FE model of multi-strokes pilgering cold roll of TA18 titanium alloy tube, the plastic deformation behavior of TA18 titanium alloy tube Phi 25.4 mmx1.32 mm during the forming process was investigated. Results show that the average total rolling force of simulation is a little larger than that of theoretical calculation. Maximal equivalent plastic strain of the final tube symmetrically appears in the pass ridge of dies deviating from 63.80 degrees, and the minimal equivalent plastic strain of the final tube appears in the above position deviating from 90 degrees. Both radial and circumferential plastic true strains are compressive strains, and axial plastic true strain is tensile strain. Meanwhile radial plastic deformation is maximal, the second is axial plastic deformation, and circumferential plastic deformation is minimal. Anisotropic characteristics of the final tube in outer surface are the heaviest, and then are the neutropause and the inner surface in sequence. There are three stages in the distributions of plastic true strain vector of middle tube, and the change curve and Q-value are different. Strain ratio of plastic true strain vector of middle tube ranges from -30 degrees (Q=0) to 0 degrees (Q=1), and then to +30 degrees (Q=infinity). The radial texture of middle tube is changed into the circumferential texture during the forming process, and the final strain ratio keeps within 20 degrees to 27 degrees in order to satisfy the stable texture state of the hexagonal close-packed metals tube.