摘要
采用Gleeble-3500热模拟试验机研究了Ti-22Al-24Nb合金在温度为900～1 110℃和应变速率为0.01～10s^(-1)条件下的高温流动应力及微观组织,分析了应变速率和变形温度对高温流动应力及热变形组织的影响。结果表明,变形温度和应变速率对Ti-22Al-24Nb合金的流动应力随变形温度的升高而降低,随应变速率的增加而升高。在α_2+B_2两相区,高应变速率下(6)ε≥1.0s^(-1))进行变形时,合金显微组织发生局部塑性流动和绝热剪切。在B_2单相区,低应变速率(6)ε≤0.1s^(-1))进行变形时,有明显的动态再结晶晶粒产生。高应变速率下,原始B_2相晶粒被明显拉长,晶界多呈不连续状态;低应变速率下变形时,随变形温度升高,合金易发生动态再结晶,当变形温度高于990℃时出现明显的动态再结晶特征;高应变速率下变形时,晶界模糊,随变形温度降低,晶界几乎全部消失,合金易发生局部塑性流动和绝热剪切。
The Gleeble-3500 thermal simulator was used to investigate the high temperature flow stress and microstructure of Ti-22Al-24Nb alloy at 900~1110℃ and 0.01~10s^-1.The effects of strain rate and deformation temperature on the flow stress and microstructure of Ti-22Al-24Nb alloy were analyzed. The results indicate that the deformation temperature and strain rate have a significant effect on the high temperature flow stress of Ti-22Al-24Nb alloy.The flow stress is decreased with the increase of deformation temperature and increased with the increase of strain rate.When the deformation is performed at a high strain rate (ε≤1.0s^-1)in the α2+B2 two-phase region,local microstructure plastic flow and adiabatic shear occur in the microstructure of the alloy.In the B2 single-phase region,when the deformation is carried out at a low strain rate (ε≤0.1s^-1),there exists obvious dynamic recrystallization grains.At high strain rates,the original B2 phase grains are significantly elongated and the grain boundaries are mostly discontinuous.Under the condition of low strain rate (ε≤0.1s^-1),the dynamic recrystallization occurs more easily with the increase of deformation temperature.With the deformation temperature higher than 990℃,apparent dynamic recrystallization characteristics begin to appear.Under the high strain rate (ε≥1.0s^-1),the grain boundary is blurred,and with the decrease of the deformation temperature,the grain boundary almost disappears,so the alloy is prone to local plastic flow and adiabatic shearing.
作者
周峰
王克鲁
鲁世强
黄赟
Zhou Feng;Wang Kelu;Lu Shiqiang;Huang Yun(Institute of Aeronautical Manufacturing Engineering,Nanchang Hangkong University)
出处
《特种铸造及有色合金》
CAS
CSCD
北大核心
2018年第12期1361-1365,共5页
Special Casting & Nonferrous Alloys
基金
国家自然科学基金资助项目(51464035)
