一种新型高强高韧TC27钛合金的高温变形行为

 采用Gleeble 3500 热模拟机对一种新型高强高韧TC27 钛合金进行等温恒应变速率压缩实验,开展TC27 钛合金的高温变形行为研究，为制定TC27 钛合金的热加工工艺提供依据。研究结果表明，TC27 钛合金应力应变曲线在变形温度较低时大致呈应变软化型；而在变形温度较高且应变速率较低时，应力应变关系曲线基本为稳态流动型。在应变速率为70 s^-1时，呈现较大幅的震荡现象。TC27 钛合金的流动应力对变形温度的敏感性在低温变形时要显著大于在高温变形时的；对应变速率的敏感程度随变形温度的升高而降低。利用实验数据对TC27 钛合金分别在700~850℃和850~1150℃温度段建立了本构方程，并具有较高的精度。通过高温变形微观组织观察，发现在变形温度高于β转变温度变形时，随变形温度提高，或应变速率降低，动态再结晶数量增加。

High Temperature Deformation Behavior of a High Strength and High Toughness TC27 Titanium Alloy

The high temperature deformation behavior of TC27 titanium alloy with high strength and high toughness was studied through isothermal constant strain-rate compression experiments using a Gleeble 3500 thermo-mechanical simulator, which might provide reference for thermal processing of TC27 titanium alloy. The results show that the stress-strain curves of TC27 titanium alloy at low temperature and high temperature roughly corresponded to the softening type and steady-state-flow type, respectively, and significant shock decline was observed when the strain rate was 70 s^-1. The dependence of temperature on flow stress at low temperature was much more significant than that at high temperature, and the dependence of strain rate decreased when the temperature was increased. Based on experimental data, two high precision constitutive equations of TC27 titanium alloy were established for temperature ranges of 700-850℃ and 850-1150℃. Observation on the microstructure shows that the amount of dynamic recrystallized grains increased with the rise of temperature or the decrease of strain rate when the temperature was higher than β transition temperature.