考虑两种晶界的各向异性双晶和三晶体晶界附近弹塑性应力场分析

采用率相关的晶体滑移有限元程序对具有不同晶体取向的双晶体晶界附近及三晶体三晶粒交汇处的弹塑性应力场进行了计算,考虑了几何晶界和物理晶界的影响.计算结果表明:双晶体及三晶体考虑几何晶界和物理晶界时,这两种晶界具有相同的应力分布趋势,只是物理晶界比几何晶界的应力集中程度小,双晶体晶界附近有较大的应力梯度,存在应力集中现象.三晶体三晶粒交汇处可能是应力集中之地也可能不造成应力集中,这主要取决于晶粒晶体取向及加载方向.由此可见,要准确理解金属材料的断裂过程,还需要从细观的角度对晶界的力学响应进行细致和深入的研究.

Elastic-plastic stress distribution near grain boundary in anisotropic bicrystals and tricrystals considering two kinds of grain boundaries

The rate-dependent crystallographic finite element program was implemented for the analysis of the elastic-plastic stress fields near grain boundary(GB) in anisotropic bicrystals and tricrystals,taking the different crystallographic orientations,geometry GB and physical GB into consideration.The results show that bicrystals and tricrystals with geometry and physical GB have the same trend of stress distribution,however physical GB's stress concentration is less than the geometry GB's.There are high stress gradient and stress concentrations near the GB.The triple junction in the tricrystals may result in the stress concentration,or may not,depending on the crystallographic orientation of the three grains and loaded direction.Thus it can be seen that it need to seriously and deeply study of the mechanical response of GB for understanding the metal fracture process.