Postponing the fracture strain of ultrafine-grained 316LN steel by sequential activations of deformation modes at 77 K

The yield strength of 316LN stainless steel is always insufficient due to the single-phase austenitic structure. We processed bulky specimens with recrystallized ultrafine-grained microstructure by cold rolling and annealing treatments. The specimens are strong and ductile at 293 K as a result of dislocation-dominated plastic deformation process. In contrast, the yield strength was doubled, and the ductility was further enhanced due to the sequentially activated deformation modes at 77 K. The yielding behavior and plastic flow were discussed based on the dramatic change of deformation mechanisms at 293 K and 77 K.