Real time correlation between flow stress and dislocation density in steel during deformation

We performed in situ compression of interstitial-free steel nanoblades using transmission electron microscopy (TEM) in order to determine the relation between the evolution of the dislocation structures and the flow stress during deformation. In the early stage of deformation, the sample deforms elastically with a few dislocation motions. The dislocation multiplication processes have been discussed. Remarkable plastic softening with increasing dislocation density is observed after the maximum stress is reached, which can be understood as a situation in which the dislocation density is the dominant factor affecting the softening based on the Johnston–Gilman model.