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

对空冷态TC11钛合金在温度750～1100℃、应变速率0．001～10．0s^-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α＋β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α＋β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β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，α＋β两相区叩值较高的范围大致为750～900℃、0．001～0．006S0和900～1000℃、0．001～0．02s^-1，分别是口片层的球化起作用和口片层的球化及α＋β→β相变同时起作用的区域；β单相区η值较高的区域大致为1000～1100℃、0．003～0．3s^-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℃、0．006～10．0s^-1，875～975℃、0．03~10．0s^-1和975~1100℃、1．0～10．0s^-1，失稳现象表现为宏观剪切、绝热剪切带和β晶粒的不均匀变形。

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 in α＋β phase field and β phase 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 in α＋β phase, but first decreases and then reaches an approximately constant value at moderate and high temperatures in α＋β phase; the flow stress decreases slightly and then tends gradually toward a constant value with increasing of stain in phase field. In the processing maps of this alloy, the domains with high value of r/in α＋βphase are about （750-900 ℃, 0.001-0.006 s1） and （900-1000℃, 0.001-0.02 s^-1）. In these two domains, the spheroidization of a lamellae occurs, and the combination of spheroidization of α lameUae and α＋β→β phase transformation happens, respectively. The domain with high value of r/in fl phase field is about （1000-1100 ℃, 0.003-0.3 sl）, 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 fl grains.