The impact of particle distributions and grain-level inhomogeneities on post-necking deformation and fracture in AA5754 sheet alloys during uniaxial tension

The influence of both particle distributions and grain structure on post-necking deformation, e.g., from localized necking to fracture, is studied using a novel edge-constrained plane strain model. An isotropic elasto-plastic material model is developed for the matrix material with grains having different strengths in terms of their Taylor factors. The Taylor factors and the grain orientations are then mapped into an FE model with a modified Voronoi method by representing grains as ellipses and updating orientations by a Taylor-Bishop-Hill (TBH) model. In contrast to the pre-necking deformation where grain-level inhomogeneity dominates, the results show that particle distributions exhibit significant influence on post-necking deformation. This is because the grain-grain property difference tends to evolve rapidly due to excessive deformation and large rigid body rotation in the localized necking band while the particle-matrix property difference does not evolve during post-necking deformation.