(1. 南昌航空大学 材料科学与工程学院，南昌 330063；
2. 南京航空航天大学 材料科学与技术学院，南京 210016；
3. 北京航空材料研究院 钛合金研究室，北京100095)
摘 要: 采用Thermecmaster-Z热模拟试验机在变形温度1 050~1 100 ℃，应变速率10−3~1 s−1的条件下进行热模拟压缩试验。采用加工硬化率处理方法对应力－应变数据进行处理，结合ln θ —ε曲线的拐点及−∂(ln θ)/∂ε —ε曲线最小值的判据，研究TA15钛合金β区变形时的动态再结晶临界条件。结果表明：在本实验条件下，TA15钛合金的ln θ —ε曲线均出现拐点及−∂(ln θ)/∂ε —ε曲线均出现最小值；临界应变随应变速率的增大及变形温度的降低而增加，且临界应变与峰值应变之间基本保持恒定值εc/εp=0.62；临界应变预测模型函数关系可以表示为εc= 0.92×10−2Z 0.0843。
关键字: 加工硬化率；动态再结晶；临界条件；TA15钛合金
during deformation of β area in TA15 titanium alloy
（1. School of Materials Science and Engineering, Nanchang Hangkong University, Nanchang 330063, China;
2. College of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China;
3. Titanium Alloys Laboratory, Beijing Institute of Aeronautical Materials, Beijing 100095, China）
Abstract:The hot simulation compression tests of titanium alloy TA15 were conducted at deformation temperature of 1 050−1 100 ℃ and strain rate of 10−3−1 s−1 with the Thermecmaster-Z hot simulation test machine. The critical conditions of dynamic recrystallization for onset of DRX during deformation of β area were obtained by computation of the work hardening rate θ from initial stress—stain data and introduction of the inflection point criterion of lnθ —ε curves and the minimum value criterion of −∂(lnθ)/∂ε —ε curves. The results indicate that an inflection point in the ln θ —ε curve appears and a minimum value of −∂(lnθ)/∂ε —ε curve is presented when the critical state is attained for this alloy. The critical strain increases with increasing the strain rate and decreasing the deformation temperature. There is linear relationship between critical strain and peak strain, i.e. εc/εp=0.65. The predicting model of critical strain is described by the function of εc=0.92×10−2Z0.0843.
Key words: work hardening rate; dynamic recrystallization; critical condition; TA15 titanium alloy
