Hot Deformation Behavior of TB8 Alloy near the β-Transus

摘要:

通过热模拟压缩试验，对TB8钛合金β相变点附近的高温变形行为进行了研究。热模拟压缩试验的变形温度为650 ~900 °C，应变速率为0.01~10 s –1。通过试验分别得到了TB8钛合金双相区(α+β)和单相区(β)的流变应力曲线，并分别研究了流变应力与变形温度、应变速率和微观组织演化的关系。在10 s-1的高应变速率下，真应力-真应变曲线在850和900 °C出现了双峰，这一现象未见报道。通过本构关系推导，得到了TB8钛合金双相区(α+β)和单相区(β)的表观激活能分别为233.0151和197.8987 kJ/mol。另外，建立了TB8钛合金双相区(α+β)和单相区(β)相应的流变应力本构方程

Abstract:

Hot deformation behavior of TB8 alloy near the β-transus was investigated via hot compression tests in the temperature range of 650~900 oC and at strain rates ranging from 0.01 s-1 to 10 s-1. The flow stress curves obtained in the dual phase α+β and single phase β regions were analyzed in terms of the different dependence on the flow stresses responding to different temperatures, strain rates and different microstructural evolutions. At the high strain rate of 10 s-1，the true-stress ture-strain curves have two peaks at temperature of 850 °C and 900 °C. This is a new phenomenon, which has not been reported before. The value of apparent activation energy is 233.0151 kJ/mol for dual phase microstructure and 197.8987 kJ/mol for single phase β microstructure. Furthermore, the corresponding flow stress constitutive equation of TB8 alloy in dual-phase and in single-phase regions is established.