热变形参数对Ti-6554合金流动软化行为的影响

Effect of Heat Deformation Parameters on Flow Softening Behavior of Ti-6554 Alloy

目的研究不同热变形参数下Ti-6554合金对应变速率敏感指数m、应变硬化指数n的影响。方法采用Gleeble-3500热模拟实验机,在变形温度为810~930℃、应变速率为0.001~10s^(-1)条件下,对Ti-6554合金进行等温恒应变速率热压缩实验。结果应变速率敏感指数m随应变速率的升高和变形温度的降低而减小,当真应变为0.9时,m在变形温度为930℃、应变速率为0.001 s^(-1)的条件下达到峰值,为0.43。应变硬化指数n随应变速率的升高呈先升高后降低的趋势,在高温区间(870~930℃)的软化程度较大。结论Ti-6554合金对变形温度、应变速率等热变形参数十分敏感,该合金的流动应力随着应变速率的升高和变形温度的降低而增大。分析微观组织可知,从应变速率敏感指数m角度考虑,该合金发生软化行为的最佳区域是变形温度为870~930℃、应变速率为0.001 s^(-1)。从应变硬化指数n的角度考虑,在变形温度为870~930℃条件下,Ti-6554合金在低应变速率区间(0.001~0.01 s^(-1))的软化行为以动态再结晶(DRX)为主,在高应变速率区间(0.1~10 s^(-1))的软化行为以动态回复(DRV)为主。

The work aims to analyze the effect of thermal deformation parameters on the strain rate sensitivity index m and the stress hardening index n of Ti-6554 alloy.The isothermal constant strain rate hot compression experiments were conducted on Ti-6554 alloy at deformation temperature of 810-930 and strain rate of 0.001℃-10 s^(-1)with a Gleeble-3500 thermal simula-tion tester.The result showed that the strain rate sensitivity index m decreased with the increase of strain rate and the decrease of deformation temperature.When the true strain was 0.9,m reached the peak of 0.43 at deformation temperature of 930 and℃strain rate of 0.001 s^(-1).The strain hardening index n tended to increase and then decrease with the increase of strain rate,and the degree of softening was greater in the high temperature range 870-930℃.Ti-6554 alloy is sensitive to heat deformation parameters such as deformation temperature and strain rate,and the flow stress of this alloy increases with the increase of strain rate and decrease of deformation temperature.Combined with the microstructure verification,the best region for the softening behavior of this alloy,considering the strain rate sensitivity index m,is the deformation temperature of 870-930℃and strain rate of 0.001 s^(-1).The softening behavior of Ti-6554 alloy in the low strain rate interval(0.001-0.1 s^(-1))with the strain hardening index n at the deformation temperature of 870-930℃is mainly based on Dynamic recrystallization(DRX)is dominant;the softening behavior in the high strain rate interval(0.1-10 s^(-1))is dominated by dynamic reversion(DRV).