TC20钛合金的变形热效应和局部流动行为

Deformation Heat Effect and Local Flow Behavior of TC20 Titanium Alloy

借助Gleeble-3800热力模拟试验机对锻态TC20钛合金进行了等温恒应变速率压缩试验,研究了该合金在变形温度为940~1030℃、应变速率为0.001~10s^(-1)条件下流动应力的变化规律。根据试验数据,计算了不同变形条件下的温升值,分析了变形热产生的规律特征。基于应变速率敏感指数m等值线图和失稳图的叠加图,结合组织观察验证,分析了热变形参数对TC20钛合金局部流动行为的影响。结果表明,TC20钛合金的流动应力随变形温度的升高而减小,随应变速率的增加而增大。变形热效应造成的温升随应变速率的增加而增大,随变形温度的升高而降低。合金在变形温度为940~990℃,应变速率为0.32~10s^(-1)下变形时,随着变形温度的降低和应变速率的增加,合金易发生局部流动。

The isothermal constant strain rate compression test of the forged TC20 titanium alloy was carried out by using Gleeble-3800 thermal simulator.The change of flow stress at 940~1030℃and strain rate of 0.001~10s^(-1) was investigated.According to the experimental data,the temperature-increment value under different deformation conditions was calculated,and the features of deformation heat generation were analyzed.Based on the superposition diagram of strain rate sensitivity exponent m contour map and instability map,the influence of thermal deformation parameters on the local flow behavior of the TC20 titanium alloy was analyzed combined with the verification of microstructure observation.The results show that the flow stress of TC20 titanium alloy is decreased with the increase of the deformation temperature and increased with the increase of the strain rate.The temperature-increment caused by the deformation heat effect is increased with the increase of the strain rate and decreased with the increase of the deformation temperature.With deformation at 940~990℃and high strain rate of 0.32~10s^(-1),the alloy is prone to local flow with the deformation temperature decreasing and the strain rate increasing.