Activation of a hybrid twinning mechanism in a Cr-Ni-Si-V-N medium manganese austenitic steel containing precipitates

Twinning nucleation in a medium Mn austenitic steel containing precipitates is studied at low strain similar to 0.02, using transmission electron microscopy. In the near vicinity of the precipitates, unfaulting dislocation reaction is favored, while twinning is activated farther from the precipitates. Twin nucleation follows a hybrid mechanism, involving creation of stacking faults through classical dislocation dissociation, while those stacking faults subsequently overlapped following a non-classical alternated stacking fault pair mechanism to create a three-layer twin nucleus. The observed twinning behavior is interpreted from an energy barrier variation viewpoint within the matrix. (C) 2020 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Automated summary

In a medium Mn austenitic steel containing precipitates, twin nucleation is influenced by unfaulting dislocation reaction near the precipitates, while twinning is activated farther from the precipitates. The formation of twin nuclei involves the creation of stacking faults through classical dislocation dissociation, followed by overlapping of these stacking faults through a non-classical mechanism to form a three-layer twin nucleus.