钛合金管材热挤压过程模拟

Simulation of the Hot Extrusion Process of Titanium Alloy Tube

摘要: 本文使用有限元软件模拟TC4管材热挤压过程。通过建立合适的有限元模型，研究了坯料初始温度为850℃、900℃、950℃和1000℃时，热挤压过程中挤压力、等效应力、等效应变及管材温度的变化规律，可以得出以下结论：(1) TC4管坯初始预热温度升高使得金属发生热软化，导致挤压力降低；随着预热温度的升高，挤压筒内的坯料应力逐渐减小，管材的变形更加均匀，但头部仍然存在挤压小变形区；(2) 出模口管材的温度由内向外呈现先升高后降低的趋势，坯料预热温度从850℃升高至1000℃时，稳态挤压出模口温升分别为93℃、64℃、40℃和16℃，挤压末期出模口管材的温降分别为10℃、40℃、66℃、104℃；(3) TC4坯料初始温度为950℃时，挤压力适中，管材挤压变形均匀，仅在管材尾部存在少量应变集中。在TC4坯料初始预热温度为950℃热挤压实验中，挤压后的组织和性能均满足使用要求，且沿壁厚方向的组织与温度变化有关，进而验证了模拟结果。

Abstract: In this paper, finite element software is used to simulate the hot extrusion process of TC4 pipe. By establishing an appropriate finite element model, the variation of extrusion pressure, equivalent stress, equivalent strain and pipe temperature during hot extrusion were studied when the initial billet temperature was 850˚C, 900˚C, 950˚C and 1000˚C. The following conclusions can be drawn: (1) The increase of initial preheating temperature of TC4 tube billet makes the metal thermal softening and leads to the decrease of extrusion pressure; with the increase of preheating temperature, the billet stress in the extrusion cylinder decreases gradually, and the deformation of the pipe becomes more uniform, but there is still a small deformation zone at the head. (2) The temperature of die outlet pipe increased first and then decreased from inside to outside. When the billet preheating temperature increased from 850˚C to 1000˚C, the temperature rise of steady-state extrusion die outlet was 93˚C, 64˚C, 40˚C and 16˚C respectively, and the temperature drop of die outlet pipe at the end of extrusion was 10˚C, 40˚C, 66˚C and 104˚C respectively. (3) When the initial temperature of TC4 billet is 950˚C, the extrusion pressure is moderate, the extrusion deformation of the pipe is uniform, and only a small amount of strain concentration exists at the end of the pipe. In the hot extrusion experiment with the initial preheating temperature of TC4 billet at 950˚C, the microstructure and properties after extrusion meet the application requirements, and the microstructure along the wall thickness direction is related to the temperature change, thus verifying that the simulation results are correct.