Abstract The TC4 titanium alloy powder test piece was prepared by spark plasma sintering. The multi-pass hot deformation of the TC4 titanium alloy was tested by using the Gleeble-1500 experiment machine. Measurement of relative density, X-ray diffraction, optical microscopy, scanning electron microscopy and electron backscatter diffraction were carried out for the TC4 titanium alloy. In order to reveal the evolution of the microstructure, describing its changes systematically is necessary, which has become the focus of this article. The results show that after multi-pass hot deformation, the relative density of the TC4 titanium alloy could reach 99.93%. With the increase in deformation and decrease in temperature, the β-transformed phase was retained, and many fine β-transformed phases were formed between two adjacent lamellar α. During the one-pass hot deformation, the rapid increase in relative density was the main reason for the instability of the flow stress in the stress–strain curve. For two-pass and three-pass hot deformations, more features of dynamic recrystallization and the characteristics of dynamic recovery at high strain rates (5 s−1) could be found. The size of the grains was about 15 µm after the three-pass hot deformation.

中文翻译：

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多道次变形对放电等离子烧结TC4钛合金组织演变的影响

摘要 采用放电等离子烧结法制备TC4钛合金粉末试件。采用Gleeble-1500实验机对TC4钛合金的多道次热变形进行了测试。对TC4钛合金进行了相对密度、X射线衍射、光学显微镜、扫描电子显微镜和电子背散射衍射的测量。为了揭示微观结构的演变，系统地描述其变化是必要的，这成为本文的重点。结果表明，经过多道次热变形后，TC4钛合金的相对密度可达99.93%。随着变形的增加和温度的降低，β-转变相得以保留，并且在相邻的两个层状α之间形成了许多细小的β-转变相。单程热变形过程中，相对密度的快速增加是应力-应变曲线中流动应力不稳定的主要原因。对于二道次和三道次热变形，可以发现更多的动态再结晶特征和高应变速率（5 s-1）下的动态回复特征。三道次热变形后晶粒尺寸约为 15 µm。