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为了优化室温下等通道转角挤压纯钛工件的几何形状,采用三维有限元软件模拟了纯钛工件的变形行为。通过对比分析工件形状和尺寸对损伤因子、挤压力以及剪切带处应变速率分布等参数的影响,获得了工件最佳几何形状。仿真结果表明,方条形工件的损伤因子大于圆棒型工件,且高于纯钛材料的临界损伤因子,表明方条形工件不利于变形,易产生表面裂纹。3D模拟结果表明,直径为15mm的圆棒型工件具有最小的损伤因子,适中的挤压载荷以及相对均匀的应变分布。依据仿真结果提供的最佳工件,即直径为15 mm的圆棒型工件,室温下成功挤压出直径15 mm的纯钛圆棒。挤压后样品截面上硬度分布均匀,与3D仿真所预示的均匀应变分布相一致。
In order to optimize the geometrical shape of the pure titanium workpiece extruded at equal channel angles at room temperature, the deformation behavior of the pure titanium workpiece was simulated by using the 3D finite element software. By comparing the influence of the shape and size of the workpiece on the damage factors, the extrusion pressure and the strain rate distribution at the shear zone, the best geometric shape of the workpiece is obtained. The simulation results show that the damage factor of square bar is larger than that of round bar, and higher than the critical damage factor of pure titanium. It shows that the square bar is unfavorable to deformation and easy to produce surface cracks. The results of 3D simulation show that the round bar with the diameter of 15mm has the smallest damage factor, the moderate compression load and the relatively uniform strain distribution. Based on the simulation result, the best workpiece, a 15 mm diameter rod, was successfully extruded at room temperature into a 15 mm diameter titanium rod. The hardness distribution of the sample after extrusion is uniform, consistent with the uniform strain distribution predicted by the 3D simulation.