Twins and twin-related domains in a grain boundary-engineered 304 stainless steel

ABSTRACTThe grain boundary (GB) network of a GB-engineered 304 stainless steel was investigated in three dimensions. The GB-engineered sample had a high proportion of twin-related boundaries (∼70%). However, these boundaries were not distributed uniformly, but rather in large-sized twin-related domains (TRDs). All grains within a TRD can be connected by a tree-shaped twin-chain. Any two grains within a TRD have ∑3n-type misorientation, where the n-value could be determined according to the twin-chain. These results show that the formation of large-sized TRDs is correlated with extensively progressed multiple-twinning processes. A quadruple-junction has three twin-boundaries at most. Furthermore, all observed quadruple-junctions within TRDs have at least one twin-boundary. The common spatial morphologies of twin-boundaries are plane-shape, tunnel-shape and semi-closed tunnel-shape.This paper is part of a thematic issue on Nuclear Materials.