Effect of twin-related boundaries distribution on carbide precipitation and intergranular corrosion behavior in nuclear-grade higher carbon austenitic stainless steel

Based on different character distribution of twin-related boundaries (Σ3n, 1 ≤ n ≤ 3) introduced by special thermomechanical processing, the effect on carbide precipitation and the resulting intergranular corrosion (IGC) behavior was investigated in depth in nuclear-grade 316H stainless steel. It was worked out that the Σ3 twin boundaries with single distribution was difficult to suppress the IGC percolation along random high-angle grain boundaries, while the interconnected Σ3 twin boundaries could fully block the percolation channel and thus greatly improve the IGC resistance. Among which, the precipitation of M23C6 carbides at different boundaries plays key role to affect their ability of resisting IGC attack.