Discontinuous Yielding Mechanisms in Tempered Hierarchical Duplex Phase Steel with High-Density Dislocations

In this study, two types of discontinuous yielding mechanisms in tempered hierarchically heterogeneous steels with high-density dislocations are elucidated. Comprehensive results demonstrate that two types of stress drop are attributed to dislocation multiplication caused by trapped dislocations breaking away from Cottrell atmospheres in the interior of grains and dislocations nucleation at phase interfaces/grain boundaries strengthened by carbon segregation, respectively. The established mathematical models based on carbon segregation-induced strengthening effect could well describe strength contribution of carbon segregation at dislocations and grain boundaries.