Ti-3Al-2.5V钛合金管织构演变规律研究

Texture development of Ti-3Al-2.5V titanium alloy tubes

摘要:

各向异性是钛合金管的一种重要性能，宏观上通常用收缩应变比（CSR）进行描述，而在微观上则可以通过织构演变分析其变化规律。本文通过EBSD方法研究了Ti-3Al-2.5V管轴向拉伸过程中的织构演变，揭示了CSR与织构演变的内在联系。结果表明，随着轴向塑性应变的增加，钛合金管α相晶体的基轴从开始变形时的沿径向分布逐渐朝着周向方向偏转，然后稳定在与径向成45°左右的位置。另外，β相在轴向拉伸过程中也表现出了明显的择优取向。正是因为织构的变化导致了CSR先迅速减小，然后缓慢减小，最后趋于稳定的变化规律。考虑到α相密排六方晶胞的基轴取向在轴向上的分量，改进了简化的CSR- f （织构量化参数）模型。与实验结果的对比表明，改进模型与实验值符合得较好。

Abstract:

The anisotropy, which is one of key mechanical properties of Ti-alloy tubes, is usually described in terms of the contractile strain ratio (CSR) macroscopically and dependent on the micro texture evolution. In order to understand the variation of CSR, the texture evolution of Ti-3Al-2.5V titanium alloy tubes is studied by Electron Back-Scattered Diffraction (EBSD). The results show that the basal poles of the α-phase inclined from the radial direction to circumferential direction and stabilized around 45° between these two directions, and the strongly preferred orientation of the β-phase was observed with the increase of axial plastic strain. This change of texture causes the CSR values to decrease rapidly in the initial stage, then decrease slowly until stabilizing in the final stage. The simple model between CSR and texture quantity parameter f is modified by incorporating the texture component in the axial direction. Comparison with experiment shows that the modified model is in better agreement with the experimental values than the simple model.