纯钛晶粒间反应应力对低轧制变形量取向变化的影响

Effect of intergranular reaction stress on orientation evolution of pure titanium grains after low rolling deformation

摘要:

用扫描电镜和背散射电子衍射技术观察了低轧制变形量工业纯钛晶粒取向与形状的变化,统计观测分析了变形过程中实际开动的滑移系,研究了变形过程中晶粒间的力学交互作用及其对滑移系开动和取向演变的影响。用Sachs模型和反应应力模型(RS模型)模拟计算了晶粒变形过程中开动的滑移系及取向的演变。结果显示,工业纯钛多晶体中各晶粒的塑性应变并不符合Taylor变形原则,Sachs模型能够部分地揭示滑移系的开动过程和取向演变的趋势。晶粒的塑性变形不仅取决于外应力的作用,晶粒间的反应应力也会对滑移系的开动和取向演变产生重要影响。采用基于晶粒间交互作用的反应应力模型可以更全面的揭示滑移系的开动过程,更准确的预测变形后的晶粒取向。晶粒间反应应力的高低受多种因素影响,其中,晶粒自身取向及其与周围晶粒取向关系对反应应力大小有重要影响。

Abstract:

The grain orientation and grain shape changes of commercial pure titanium after low rolling deformation were observed using scanning electron microscope and backscattering electron diffraction techniques, and the actual active slip systems during deformation process were analyzed statistically. The mechanical interaction between grains and its influence on the slip systems selection and orientation evolution of grains were studied. The active slip systems and orientations’ evolution of rolling grains were simulated using Sachs model and Reaction Stress model. The results show that the plastic strain of grains in the polycrystalline commercial pure titanium is not in accordance with Taylor deformation principle, and the Sachs model can partly reveal the mechanism of slip and trend of the orientation evolution. The plastic deformation of grains depend not only on the external stress, but also on the reaction stress between grains, which influence the selection of slip systems. The Reaction Stress model based on the grains’ interaction can be used to reveal the activation process of the slip systems more comprehensively, and to predict the grain orientation after deformation more accurately. The reaction stress between grains is influenced by many factors, among which, the orientation of grains and its relation to the grain orientation have important impact on the magnitude of the reaction stress.