空冷态TC11钛合金的高温流变行为及加工图

High Temperature Flow Behavior and Processing Map for Air-Cooled Titanium Alloy TC11

摘要:

对空冷态TC11钛合金在温度750~1100 ℃、应变速率0.001~10.0 s-1范围内进行等温压缩实验，利用流动应力-应变曲线和加工图研究了该合金在两相区和单相区的高温流变行为、流变失稳现象及变形机制。结果表明，在两相区，流动应力超过峰值后在低温区随应变的增大持续下降，在中、高温区先下降最后趋于接近稳定的应力值；在单相区，流动应力随应变的增大略有下降然后逐渐趋于稳定。在加工图上，两相区值较高的范围大致为750~900 ℃、0.001~0.006 s-1和900~1000 ℃、0.001~0.02 s-1，分别是片层的球化起作用和片层的球化及相变同时起作用的区域；单相区值较高的区域大致为1000~1100 ℃、0.003~0.3 s-1，是动态再结晶起作用的区域。这些区域均是良好的加工区域。流变失稳区为750~875 ℃、0.006~10.0 s-1，875~975 ℃、0.03~10.0 s-1和975~1100 ℃、1.0~10.0 s-1，失稳现象表现为宏观剪切、绝热剪切带和晶粒的不均匀变形。

Abstract:

The isothermal compression tests for air-cooled titanium alloy TC11 were carried out in the temperature range of 750~1100 ℃ and strain rate range of 0.001~10.0 s-1, and the high temperature flow behavior, the flow instability and the deformation mechanism were investigated inphase field andphase field for this alloy by using flow stress-strain curve and processing map. The results show that in excess of peak stress the flow stress decreases continuously with increasing of strain at low temperatures inphase, but first decreases and then reaches an approximately constant value at moderate and high temperatures inphase; the flow stress decreases slightly and then tends gradually toward a constant value with increasing of stain inphase field. In the processing maps of this alloy, the domains with high value of in phase are about (750~900 ℃, 0.001~0.006 s-1) and (900~1000 ℃, 0.001~0.02 s-1). In these two domains, the spheroidization oflamellae occurs, and the combination of spheroidization of lamellae andphase transformation happens, respectively. The domain with high value of inphase field is about (1000~1100 ℃, 0.003~0.3 s-1), where dynamic recrystallization undergoes. The above domains are desirably to be selected for hot working. The domains of flow instability are (750~875 ℃, 0.006~10.0 s-1), (875~975 ℃, 0.03~10.0 s-1) and (975~1100 ℃, 1.0~10.0 s-1), and the manifestations of flow instability are macroscopic shear, adiabatic shear band and non-uniform deformation of grains.