TC18钛合金热压缩本构方程及热加工图

Constitutive Equation and Processing Map of Thermal Deformation for TC18 Titanium Alloy

摘要:

在温度为750~950 ℃、应变速率为0.01~10 s-1、变形程度为60%的条件下对TC18钛合金的高温流变应力变化规律进行热模拟实验研究。采用Arrhenius双曲正弦函数推导出TC18本构方程。以热模拟压缩实验为基础建立了真应变0.3、0.5时TC18钛合金热加工图。结果表明：TC18钛合金流变应力随着变形温度升高而降低，随着应变速率的升高而升高；在本实验条件下 TC18钛合金表现出动态回复和动态再结晶两种软化机制；Arrhenius双曲正弦函数能够很好地描述TC18钛合金本构方程。热加工图结果表明：在真应变为0.3时存在3个非稳定区域，在应变为0.5时存在2个非稳定区域。结合热加工图，较佳的热加工区间在温度为830~920 ℃，应变速率为0.01~0.32 s-1区域内

Abstract:

The changing rules of flow stress at high temperatures for TC18 titanium alloy were studied by thermal simulation experiment, in temperature ranging from 750 to 950 ℃, at strain rate from 0.01 to 10 s-1 and the deformation degree of 60%. The constitutive equation of TC18 Ti alloy was derived through Arrhenius hyperbolic sine function. According to the experimental results, the processing maps of TC18 Ti alloy were developed for strain of 0.3 and 0.5. The results show that flow stress of TC18 titanium alloy decreases with the increase of deformation temperature and the decrease of strain rate. Under the experimental conditions, TC18 titanium alloy shows two kinds of softening mechanism of dynamic recovery and recrystallization. Arrhenius hyperbolic sine function can well describe the constitutive equation of the TC18 titanium alloy. The result of processing map shows that three unsteady zones of high temperature deformation appear on the process map at strain of 0.3. The two unsteady zones of high temperature deformation appear on the process map at strain of 0.5. From the processing maps, better thermal processing interval is in a temperature of 830 ~ 920 ℃ and at strain rate of 0.01~0.32 s-1 region