基于热加工图的Ti-46.5Al-2.5V-1.0Cr-0.3Ni合金高温变形特性研究

Hot deformation characteristics of Ti-46.5Al-2.5V-1.0Cr-0.3Ni alloy using processing maps

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 hot deformation behaviors of Ti-46.5Al-2.5V-1.0Cr-0.3Ni alloy in the temperature range of 1000-1200℃ and strain rate range of 0.001-1.0s-1 were studied using hot compressing testing on a Gleeble-1500 simulator.And a processing map was developed on the basis of these data and the principles of dynamic material modeling.The map exhibits two domains： the first one at 1100℃ and 0.01s-1 with a peak efficiency of power dissipation of 34%,the second one at 1105℃ and 0.001s-1 with a peak efficiency of power dissipation of 34%.Optical microscopic observations show that they represent two dynamic recrystallization（DRX） domains with different mechanisms.At temperatures lower than 1140℃ and strain rates higher than 0.01s-1,the material may be subjected to potential instabilities for the inhomogeneous growing of dynamic recrystallization grains during the hot deformation.At temperatures 1000-1130℃ and strain rates higher than 0.02s-1,the shear crack of the samples is obviously.On the basis of the above processing map,the hot deformation should be carried out in the dynamic recrystallization domains Ι.