摘要
The high temperature deformation behaviors of α＋β type titanium alloy TC11 （Ti-6.5Al-3.5Mo-1.5Zr-0.3Si） with coarse lamellar starting microstructure were investigated based on the hot compression tests in the temperature range of 950-1100 ℃ and the strain rate range of 0.001-10 s-1. The processing maps at different strains were then constructed based on the dynamic materials model, and the hot compression process parameters and deformation mechanism were optimized and analyzed, respectively. The results show that the processing maps exhibit two domains with a high efficiency of power dissipation and a flow instability domain with a less efficiency of power dissipation. The types of domains were characterized by convergence and divergence of the efficiency of power dissipation, respectively. The convergent domain in a＋fl phase field is at the temperature of 950-990 ℃ and the strain rate of 0.001-0.01 s^-1, which correspond to a better hot compression process window of α＋β phase field. The peak of efficiency of power dissipation in α＋β phase field is at 950 ℃ and 0.001 s 1, which correspond to the best hot compression process parameters of α＋β phase field. The convergent domain in β phase field is at the temperature of 1020-1080 ℃ and the strain rate of 0.001-0.1 s^-l, which correspond to a better hot compression process window of β phase field. The peak of efficiency of power dissipation in ℃ phase field occurs at 1050 ℃ over the strain rates from 0.001 s^-1 to 0.01 s^-1, which correspond to the best hot compression process parameters of ,8 phase field. The divergence domain occurs at the strain rates above 0.5 s^-1 and in all the tested temperature range, which correspond to flow instability that is manifested as flow localization and indicated by the flow softening phenomenon in stress-- strain curves. The deformation mechanisms of the optimized hot compression process windows in a＋β and β phase fields are identified to be spheroidizing and dynamic recrystallizing controlled by self-diffusion mechanism, respectively. The microstructure observation of the deformed specimens in different domains matches very well with the optimized results.
基于粗层片原始组织的α＋β型TC11钛合金的热压缩实验,研究了该合金在950-1100°C、0.001-10s1条件下的热变形行为;依据动态材料模型构建了不同应变下的加工图,并对热压缩工艺参数和变形机制分别进行优化和分析。结果表明,加工图中存在2个功率耗散效率较高区和1个功率耗散效率较低的流变失稳区。这些区域的功率耗散效率呈现出收敛或发散的特征。在α＋β两相区,功率耗散效率收敛区位于950-990°C、0.001-0.01s1范围,其峰值功率耗散效率出现在950°C、0.001s1,前者和后者分别为α＋β两相区较佳和最佳的热压缩工艺窗口;在β单相区,功率耗散效率收敛区位于1020-1080°C、0.001-0.1s1范围,其峰值功率耗散效率出现在1050°C、0.001-0.01s1,前者和后者分别为β相区的较佳和最佳的热压缩工艺窗口。功率耗散效率发散区位于应变速率大于0.5s1的范围内,其对应的流动失稳机制为局部流动,此时流变应力呈现出流变软化现象。在α＋β两相区和β单相区优化工艺窗口内的变形机制分别为动态球化和自扩散控制的动态再结晶。优化结果与变形组织观察结果吻合良好。
基金
Project (51005112) supported by the National Natural Science Foundation of China
Project (2010ZF56019) supported by the Aviation Science Foundation of China
Project (GJJ11156) supported by the Education Commission of Jiangxi Province, China
Project(GF200901008) supported by the Open Fund of National Defense Key Disciplines Laboratory of Light Alloy Processing Science and Technology, China
