A commercial SUS316LN stable austenitic stainless steel plate was 92% cold-rolled to develop complicated heterogeneous nanostructure comprising “eye”-shaped twin domains, shear bands and conventional low-angle lamellae (Fig. 1). The grain-boundary spacings in the twin domains and the low-angle lamellae were about 25 nm and 40 nm in average, respectively. The shear bands with an average width of about 40 nm were composed of finer grains. The mechanical properties showed large anisotropy that the tensile strength along transverse direction (TD), 1.9 GPa, was higher than that along rolling direction (RD), 1.6 GPa (Fig. 2). The tensile strength was more raised by peak aging at 748 K up to 2.2 GPa and 1.9 GPa, respectively. Nevertheless, it possessed moderate ductility. The quite high tensile strength and anisotropy of the mechanical properties could be reasonably understood from the distribution of the heterogeneous-nanostructure components and crystallographical orientations. Still more, the 3D-atom probe tomography analyses revealed that segregation of solute elements at twin and low-angle lamellar boundaries caused additional strengthening by aging. Therefore, it was found that combined strengthening mechanisms of nano-lamellar structures in the heterogeneous nanostructure and grain-boundary segregation derived marvelously high strength without largely spoiling ductility.