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在Gleeble-1500热模拟机上对Ti-46.5Al-2.5V-1.0Cr-0.3Ni合金进行了热压缩实验,采用动态材料模型的加工图研究了其在1000~1200℃和0.001~1.0 s-1条件下的热变形行为。结果表明,Ti-46.5Al-2.5V-1.0Cr-0.3Ni合金在热变形时呈现两个微观机制不同的动态再结晶峰区,其中动态再结晶区域Ι区:峰值效率为34%,峰值对应的温度和应变速率分别为1100℃和0.01 s-1;动态再结晶区域ΙΙ区:峰值效率为34%,峰值对应的温度和应变速率分别为1105℃和0.001 s-1。在温度低于1140℃、应变速率大于0.01 s-1范围内进行热加工时,由于热塑性变形过程中再结晶晶粒的不均匀长大,极易导致试样变形开裂。在温度1000~1130℃,变形速率大于0.02 s-1区域内,热压缩变形试样外表面剪切开裂趋势明显,易引起加工失稳。根据热加工图分析结果可知,Ti Al合金热变形时应选择在动态再结晶Ι区内进行。
The thermal compression test of Ti-46.5Al-2.5V-1.0Cr-0.3Ni alloy was carried out on a Gleeble-1500 thermal simulator. The dynamic mechanical model was used to study the thermal compression behavior of Ti-46.5Al-2.5V-1.0Cr-0.3Ni alloy at 1000-1200 ℃ and 0.001-1.0 s -1 Under the conditions of thermal deformation behavior. The results show that Ti-46.5Al-2.5V-1.0Cr-0.3Ni alloy has two microscopic dynamic recrystallization peaks during thermal deformation. The dynamic recrystallization region ichi region has a peak efficiency of 34% and its peak corresponds to The temperature and strain rate of the zone 1 were 110 ℃ and 0.01 s-1, respectively. The peak area efficiency of the ΙΙ dynamic recrystallization area was 34%. The corresponding peak temperature and strain rate were 1105 ℃ and 0.001 s-1, respectively. When the temperature is lower than 1140 ℃ and the strain rate is greater than 0.01 s-1, the deformation and cracking of the specimen can be easily caused by the non-uniform recrystallization grain growth during the thermoplastic deformation. In the temperature range of 1000 ~ 1130 ℃ and deformation rate greater than 0.02 s-1, the tendency of shear cracking on the outer surface of the hot compressive deformation specimen is obvious, which may lead to instability of processing. According to the results of the hot working diagram analysis, it can be seen that the TiAl alloy should be selected in the dynamic recrystallization zone 1 when it is hot deformed.