Correlation of grain boundary connectivity with grain boundary character distribution in austenitic stainless steel

Abstract

The connectivity of grain boundaries can be an important microstructural parameter governing the bulk properties of polycrystalline materials as well as the grain boundary character distribution. On the basis of the percolation theory, the connectivity of random boundaries that are susceptible to percolative phenomena like corrosion in a polycrystal has been quantitatively evaluated and examined in connection with the grain boundary character distribution in austenitic stainless steel. The percolation threshold has been found to occur at a fraction of approximately 70 ± 5% coincident site lattice (CSL) boundaries (30 ± 5% random boundaries). The maximum random boundary cluster length drastically decreases and the frequency of resistant triple junctions increases with increasing frequency of the CSL boundaries near the percolation threshold. An increase in the frequency of resistant triple junctions can enhance corrosion resistance of polycrystalline austenitic stainless steel even if the grain boundary character distribution is the same.