Mechanism of Balanced Strength and Ductility in High-Strength Low-Alloy Steel

A high-strength low-alloy steel with balanced strength and ductility was reported. A product of the strength and elongation (PSE) at a break of ~19 GPa% was obtained. The microstructure of the material was investigated by scanning electron microscopy, electron backscattered diffraction, and transmission electron microscopy methods. Phase transformation follows the K–S orientation relationships. Interconnecting structures generate due to the variant interactions within one prior austenite grain. The multi-phase microstructure containing both soft and hard phases contributes to good plasticity. The homogeneously distributed NbC nanoparticles make up the loss of strength ascribed to the soft retained austenite and keep the strength at an extremely high level.