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基于TC8钛合金的等温压缩实验,对其高温变形过程中的不连续屈服现象(DYP)进行研究。首先引入上、下屈服点差值(?σUL)和应力振荡结束时的应变(εOSC)两个参数,根据应力-应变曲线,对TC8钛合金的不连续行为进行数值表征;然后,分析变形工艺参数对?σUL值和εOSC值的影响。结果表明:?σUL值和εOSC值随着应变速率的增大而增大;在不同的应变速率下,变形温度对?σUL值的影响不同。最后,透射电子显微镜(TEM)观察结果为不连续屈服行为的动态理论提供了证据,不连续屈服行为归因于晶界产生的移动位错。同时,光学显微镜(OM)观察结果表明,初生α相和β相的晶粒尺寸随应变速率的增大而减小,从而揭示了变形工艺参数对?σUL和εOSC值的影响机制。
Based on the isothermal compression experiments of TC8 titanium alloy, the discontinuous yield phenomenon (DYP) during the high temperature deformation was studied. Firstly, two parameters of σδUL and εOSC at the end of the stress oscillation were introduced to characterize the discontinuity of TC8 titanium alloy according to the stress-strain curve. Then, the deformation process The influence of parameters on σUL and εOSC values. The results show that σUL and εOSC values increase with the increase of strain rate. The effect of deformation temperature on σUL values is different at different strain rates. Finally, transmission electron microscopy (TEM) observations provide evidence for the dynamic theory of discontinuous yield behavior due to the movement dislocations created by the grain boundaries. At the same time, the results of optical microscope (OM) show that the grain size of primary α phase and β phase decrease with the increase of strain rate, which reveals the influence of deformation process parameters on σUL and εOSC.