Influence of the grid cell geometry on 3D cellular automata behavior in intergranular corrosion

The bulk structure of stainless steels (SS) consists of mostly convex grains whose thin (one nm) planar interfaces are called grain boundaries (GB). There are industrial contexts where SS exposed to aggressive oxidative media undergo a fast degradation due to inter-granular corrosion (IGC), a preferential attack that occurs at the grain boundaries, propagating along them and leading to grains detachment. To address the IGC issue, we developed a 3D synchronous cellular automata (CA) model. Our first goal was to obtain a GB corrosion rate that could be as isotropic as possible. We performed full angular studies, with respect to the spatial orientation of a single grain boundary, in three different cases of grid (array of cells) geometry (cubic, hexagonal close-packed (HCP), face-centered cubic (FCC)). The HCP grid appears to be the best choice, as far as isotropy of the GB corrosion rate is concerned. (authors)