β-CEZ钛合金的热变形行为及加工图

Hot Deformation Behavior and Processing Map of β-CEZ Titanium Alloy

摘要:

使用Gleeble-3800热模拟试验机在温度为800~1000℃、应变速率为0.01~10s-1、变形程度为70%的条件下对锻态β-CEZ钛合金进行热模拟试验。利用试验数据及Prasad判据绘制了真应力-真应变曲线和加工图，通过其研究了该合金在α β两相区和β单相区的高温变形行为、变形失稳现象和变形机制。结果表明：本实验条件下β-CEZ钛合金表现出动态回复和动态再结晶两种软化机制，在α β两相区流动应力达到峰值后随应变的增大而缓慢下降，在β单相区流动应力达到峰值后发生不连续屈服现象快速下降一段后趋于稳定；功率耗散率η出现极大值的区域在α β两相区为850~890℃/0.01~0.05s-1，是片层α相球化的区域；在β单相区为940~980℃/0.2~0.6s-1，是动态再结晶区域；流动失稳区为800~850℃/0.1~10s-1，850~900℃/0.1~5s-1，900~1000℃/1~10s-1，失稳现象在α β两相区表现为绝热剪切带，在β单相区表现为不均匀变形。

Abstract:

The hot deformation behaviors of β-CEZ alloy in the temperature range of 800~1000℃ and strain rate range of 0.001~10s-1 have been studied by hot compressing testing on a Gleeble-3800 simulator at the deformation degree of 0.7. The high temperature deformation behavior, the flow instability and the deformation mechanism in α β phase field and β phase field were studied by the true stress-true strain curves and processing map, which were established based on experimental data and Prasad criterion. The results shows that under the experimental conditions, β-CEZ titanium alloy shows two kinds of softening mechanism: dynamic recovery and recrystallization. The flow stress decreases continuously in α β phase field after the peak stress, decreases slightly and then tends gradually toward a constant value β phase field. The domains with high value of the efficiency of power dissipation (η) at α β phase field is 850~890℃/0.01~0.05s-1, which is the spheroidization of α lamellae area. And the domains with high value of the efficiency of power dissipation (η) at β phase field is 940~980℃/0.2~0.6s-1, which is the dynamic recrystallization area. The domains of flow instability are 800~850℃/0.1~10s-1, 850~900℃/0.1~5s-1 and 900~1000℃/1~10s-1. The manifestations of the flow instability at the α β phase field is the adiabatic shaer band, at the β phase field is the non-uniform deformation.