Deformation mechanisms of a modified 316L austenitic steel subjected to high pressure torsion

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 (Tdef > 450 °C) the dominant deformation mechanism is dislocation glide whereas for medium temperatures (450 °C > Tdef > 20 °C) mechanical twinning is observed. At very low deformation temperatures (20 °C > Tdef > −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.