基于极性交互模型的TC20钛合金工艺参数优化及高温变形行为

High temperature deformation behavior and processing parameters optimization of TC20 titanium alloy based on polar reciprocity model

利用Gleeble-3800热模拟试验机对TC20钛合金进行了等温恒应变速率压缩实验,研究了其在变形温度940~1030℃、应变速率0.001~10 s^-1条件下的高温变形行为。根据实验所获得的数据,建立了包含Z参数的Arrhenius本构模型,并计算了变形激活能。结果表明:TC20钛合金的流动应力随变形温度的升高而减小,随应变速率的增加而增大,其变形激活能远高于纯α钛和β钛的自扩散激活能。基于极性交互模型原理,构建了PRM加工图。通过观察变形失稳区和稳定区的显微组织,发现失稳区的变形机制为局部流动,稳定区的变形机制为球化和动态再结晶。经综合分析,确定了TC20钛合金的最佳热加工工艺参数范围为:变形温度955~995℃,应变速率0.032~0.32 s^-1和变形温度1000~1030℃,应变速率0.001~0.018 s^-1。

The isothermal constant strain rate compression experiments of TC20 titanium alloy were carried out using a Gleeble-3800 thermal simulation testing machine to study its high temperature deformation behavior at deformation temperature of 940-1030 ℃ and strain rate of 0.001-10 s^-1. The Arrhenius constitutive model containing Z parameters was established according to the data obtained from the experiment, and the deformation activation energy was calculated. The results show that the flow stress of the TC20 titanium alloy decreases with the increase of deformation temperature and increases with the increase of strain rate, and its deformation activation energy is much higher than that of the self-diffusion activation energy of pure α titanium and β titanium. Based on the principle of polar reciprocity model, the PRM processing map was constructed. By observing the microstructure of the deformation instability region and the stability region, it is found that the deformation mechanism of the instability region is flow localization, and the deformation mechanism of the stability region is spheroidization and dynamic recrystallization. Through comprehensive analysis, the optimum hot working process parameters of the TC20 titanium alloy are determined as follows: deformation temperature of 955-995 ℃, strain rate of 0.032-0.32 s^-1 and deformation temperature of 1000-1030 ℃, strain rate of 0.001-0.018 s^-1.