TA18钛合金管材多行程皮尔格冷轧过程三维有限元模拟：II 塑性变形行为分析

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

摘要:

利用已建立的TA18钛合金管材多行程皮尔格冷轧三维有限元模型，研究了F 25.4 mm×1.32 mm的TA18钛合金管材轧制塑性变形行为。结果表明：平均总轧制力模拟结果比理论结果稍大。轧成管最大等效塑性应变对称出现在轧辊周向面孔型脊部偏转约63.80°的位置，而最小/最大等效塑性应变的位置相差约90°。轧成管径向和周向受压应力，轴向受拉应力，且变形程度径向最大，轴向次之，切向最小。轧成管各向异性程度从外表面到中性层再到内表面依次减小。工作锥径向塑性真应变矢量的变化分为3个阶段，其变化趋势和Q值各不相同，塑性真应变矢量的应变比变化范围是从–30o（Q=0）到0o（Q=1）再到+30o（Q=∞），且工作锥经历了从径向织构到周向织构的转变，使得最终应变比保持在20o到27o之间，管材达到了六方晶体管材织构分布的稳定状态。

Abstract:

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 F 25.4 mm×1.32 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°, and the minimal equivalent plastic strain of the final tube appears in the above position deviating from 90°. 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° (Q=0) to 0° (Q=1), and then to +30° (Q=￥). The radial texture of middle tube is changed into the circumferential texture during the forming process, and the final strain ratio keeps within 20° to 27° in order to satisfy the stable texture state of the hexagonal close-packed metals tube.