On the effect of deformation twinning on defect densities

The defect density of materials undergoing severe deformation twinning may be extremely low. This was in particular observed in nitrogen bearing austenitic steel deformed at low temperature. The present work discusses the effects of glide-twinning and twinning-twinning interactions with respect to defect densities. It turns out that under continuous deformation the glide-twinning interaction decreases the twin density but the twin density stays constant owing to the effect of twinning-twinning interaction. The density of mobile dislocations decreases in most situations while sessile and blocked dislocations are introduced. As the main result, untwinning and dislocation annihilation eliminate a high fraction of defects. Therefore, the residual defect density is much smaller if deformation twinning is active than it is after pure glide deformation. (C) 1997 Elsevier Science S.A.