TA15合金高低温恒应变速率拉伸变形行为对比研究

为进一步研究钛合金超塑性变形行为，对TA15合金在变形温度700~900 ℃、应变速率1×10?2~1×10?4 s?1条件下进行恒应变速率拉伸实验，对比不同温度、不同应变速率下合金的变形行为。结果表明:TA15合金在初生等轴α相平均尺寸15 μm的条件下，拉伸试样的伸长率为73.3%~250.0%；在850 ℃、1×10?4 s?1变形条件下，试样伸长率最高；在700~750 ℃下，合金表现出的峰值应力较大；在750 ℃、1×10?4 s?1变形条件下，试样伸长率为183.3%。合金试样仅在高温及低应变速率条件下出现稳态流变阶段，该阶段持续时间越长，合金的伸长率越高。变形后的TA15合金组织均发生不同程度的长大，经高温、低应变速率的变形，试样组织粗化现象最为明显。

Comparison of Tensile Deformation Behavior of TA15 Alloy at Constant Strain Rate with High-Low Temperature

In order to further study the superplastic deformation behavior of titanium alloys, the tensile tests of TA15 alloy at constant strain rate were carried out with temperature ranging from 700 to 900 ℃,and strain rate changing from 1×10?2 to 1×10?4 s?1. The deformation behaviors were compared at different deformation temperatures and strain rates. The results show that the elongation of TA15 alloy rangs from 73.3% to 250.0% when the size of initial equiaxed α phase is 15 μm on average. The highest elongation is achieved at 850 ℃ and 1×10?4 s?1. In the low temperature range of 700 to 750 ℃, the alloy demonstrates a higher peak stress. At 750 ℃, 1×10?4 s?1 deformation, the elongation of TA15 alloy is 183.3%. Steady rheological stage of TA15 alloy only appears at high temperature and low strain rate. The longer the duration of this stage, the higher the elongation of the alloy. The microstructure after various deformation have grown up in different degrees, and the microstructure of the sample after deformation at high temperature and low strain rate has the most obvious coarsening.