粉末冶金TC4钛合金热压缩动态软化行为分析

Dynamic Softening Behavior Analysis of Powder Metallurgy TC4 Titanium Alloy During Hot Compression

对粉末冶金TC4钛合金在温度为850~950℃,应变速率为0.1~10 s^(-1)范围内进行热模拟压缩实验获得了应力-应变曲线,建立了材料本构方程,描述了粉末冶金TC4钛合金的流变行为。进一步对动态软化行为进行了分析,并计算了各种因素对软化的影响程度。结果表明:变形温度越低,应变速率越小,流动软化程度越大;在应变速率为1和10s^(-1)时,主要是变形热导致流动软化;当应变速率为0.1 s^(-1),温度为850和900℃时,有变形热、动态相变和α相形态演化3种软化因素,且温度越低,α相形态演化导致的软化占比越大,温度增加,动态相变软化所占比例增加;当应变速率为0.1s^(-1),变形温度为950℃时,有变形热和动态相变2种软化因素,随着变形量增加,动态相变软化所占比例增大。

Thermal simulation compression experiments for the powder metallurgy TC4 titanium alloy were carried out at the temperature of 850~950 ℃ and the strain rate of 0.1~10 s^(-1), and the stress-strain curves were obtained. The constitutive equation of the material was established, which described the rheological behavior of the powder metallurgy TC4 titanium alloy. Furthermore, the dynamic softening behavior was analyzed, and the influence degree of various factors on softening was calculated. The results show that with the decrease of deformation temperature and the strain rate, the flow softening degree increases. When the strain rate is 1 and 10 s^(-1), the flow softening is mainly caused by the deformation heat. When the strain rate is 0.1 s^(-1) and the temperatures are 850 and 900 ℃, there are three softening factors: deformation heat, dynamic phase transformation and α phase morphology evolution. As temperature decreases, the softening proportion caused by morphological evolution of α phase increases. With the increase of temperature, the softening proportion of dynamic phase transformation increases. When the strain rate is 0.1 s^(-1) and the deformation temperature is 950 ℃, there are two softening factors: deformation heat and dynamic phase transformation. With the increase of deformation, the proportion of dynamic phase transfor mation softening increases.