Grain rotations during uniaxial deformation of gradient nano-grained metals using crystal plasticity finite element simulations

Gradient nano-grained (GNG) metals have great application potential due to its outstanding performance in both strength and ductility. In this paper, we investigate the uniaxial deformation response of GNG Cu utilizing the developed size-dependent crystal plasticity model with random initial grain lattice orientation implemented by the user-material subroutine of ABAQUS. The results show that the grain size gradient leads to gradient distribution of stress and strain, consistent with the results in the literature. In addition, the Lode parameter also shows a gradient distribution with the value closer to zero at the small-grained surface regions. Importantly, we discover that the magnitude of grain rotation strongly depends on the initial lattice orientation of the grain, but does not depend on the grain size in the current crystal plasticity finite element framework. Furthermore, we gave a reasonable explanation for the distribution of grain rotation magnitudes. Our study provides insights into the outstanding mechanical properties of GNG metals and the evolution of texture.