Evolution of dislocations and twins in high cycle fatigue of a twinning-induced plasticity steel

In the present study, fully reverse tension-compression fatigue tests were carried out to investigate the high cycle fatigue behavior of a twinning-induced plasticity (TWIP) steel. By detailed transmission electron microscopy characterization, it is revealed that the dislocation evolution during cyclic loading of the present TWIP steel consists of simultaneous dislocation multiplication and rearrangement into irregular dislocation clusters and dislocation cells. The formation of cell structure can be promoted by higher stress amplitude. A small number of deformation twins were found even though the stress amplitude during cyclic loading is lower than the yield stress. As there are no massive deformation twins formed during the high cycle fatigue tests, the present TWIP steel exhibits no better fatigue property compared to other austenitic steels.