Analysis of crystal slip and stress field in bicrystal with and without a void in the grain boundary

Based on finite deformation crystallographic constitutive theory, the bicrystals with a void and without a void in the grain boundaries (GBs) are studied, which are perpendicular and parallel grain boundary relative to the tensile axis. The stress distributions near the grain boundaries, the resolved shear stress of the slip systems and growth of the void are analyzed by three-dimensional anisotropic crystallographic finite element method, taking the different crystallographic orientations into consideration. The numerical results of bicrystal models show that there are a high stress gradient and stress concentration near the grain boundary. The features of stress concentrations are dependent on the crystallographic orientation of the two grains. At the same loading parameter, the activating law of the slip systems is relative to the difference of the two grain's crystallographic orientation. The volume of the void depends on crystallographic orientation and the direction of loading on the bicrystal. The void grows more easily in the perpendicular grain boundary. Also, the growth rate rises after slip systems are activated. The calculation indicates that it is only by the detail study of the stress distribution that the bicrystal and polycrystal deformation, damage and failure can be understood deeply.