In-situ TEM investigation on deformation mechanisms of a fine-grained 316L stainless steel

The present study explores the deformation behavior of fine-grained 316L stainless steel through in-situ tensile transmission electron microscopy (TEM), with a focus on both intergranular and intragranular deformation. The results demonstrate that grain boundaries are a critical factor in accommodating plastic deformation and serve as the primary dislocation sources (DS) for dislocation emission into the grain interior. The propagation of plastic deformation within grains occurs through the successive activation of grain boundary DSs. In addition, the fine-grained sample exhibits active deformation twin and cross-slip of extended dislocations due to its proper apparent stacking fault energy (SFE) of 27 mJ/m2 and high internal stress, which significantly enhances its strain hardening ability. These findings shed light on the underlying mechanisms of plastic deformation in fine-grained 316L stainless steel and have important implications for the design of metallic materials with superior mechanical properties.