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The present work is assigned to the microstructural evolution of a modified 316L stainless steel during high pressure torsion (HPT) in a temperature range between −196°C and 720°C. The aspect of microstructural evolution is similar to that of materials with low stacking fault energy: at high deformation temperatures (T_def>450°C) the dominant deformation mechanism is dislocation glide whereas for medium temperatures (450°C>T_def>20°C) mechanical twinning is observed. At very low deformation temperatures (20°C>T_def>−196°C) mechanical twinning is replaced by the deformation induced martensite transformation γ(fcc)→ɛ(hcp). Based on the present results, the formation mechanisms of nanocrystalline austenite are discussed.