TC17合金在α+β两相区变形时的显微组织演变及其对流动应力的影响（英文）

Microstructure evolution and its effect on flow stress of TC17 alloy during deformation in α+β two-phase region

基于显微组织表征和等温热模拟压缩试验,研究TC17 合金在α+β两相区变形时的显微组织演变及其对流动应力的影响。研究表明:当变形温度为820 和850℃时,随着应变的增加,α相的球化率略微增加;随着变形温度的升高,α相的球化率略微增加,但是α相的体积分数明显减小。当变形温度为780℃、应变速率为1 s^-1 时,流动应力呈减小趋势;当应变为1.2 时,由于位错湮没和α片层转动,流动应力未达到稳定状态。当变形温度为820 和850℃、应变速率为1 s^-1、应变大于0.8 时,由于加工硬化和动态软化的平衡作用,流动应力呈稳定状态。合金动态软化归因于α片层转动、动态回复和轻微的球化。

The microstructure evolution and its effect on flow stress of TC17 alloy during deformation in the α+β two-phase region were investigated via microstructure characterization and isothermal compression tests. Results showed that the spheroidized rate of α phase at 820 and 850℃ slightly increased with increasing strain. With increasing deformation temperature, the spheroidized rate of α phase showed a slight increasing trend, but the volume fraction of α phase significantly decreased. The flow stress at 780 ℃ and 1 s^-1 decreased continuously and steady state condition was not achieved up to strain of 1.2 due to dislocation annihilation and α lamellae rotation. Under this condition, the dynamic spheroidization was retarded. At the deformation temperatures of 820 and 850℃, and a strain rate of 1 s^-1, a steady state flow stress was observed at strains above 0.8 due to the balance between work hardening and dynamic softening. The dynamic softening was attributed to the α lamellae rotation, dynamic recovery and a little spheroidization.