Abstract Scope |
The present work demonstrates that exceptional damage-tolerance can be achieved in an ultra-strong deformed and partitioned (D&P) steel with a yield strength of ~2GPa. We demonstrate that increasing the yield strength is not detrimental to the toughness, but instead it can facilitate the activation of a delamination toughening mechanism. Specifically, the ultrahigh yield strength enables a secondary fracture mode, delamination cracking, at interfaces normal to the primary fracture surface. Delamination toughening associated with intensive but controlled cracking at Mn-enriched prior-austenite grain boundaries normal to the primary fracture surface provides an extra energy release rate for fracture as well as enhancing crack-tip blunting, collectively elevating the overall fracture toughness. Such delamination toughening combined with transformation-induced plasticity (TRIP) toughening are rarely realized simutaneously in structural materals. The combination enables an intringuing combination of strengh, ductility and toughness properties in the D&P steel. |