The Significance of Retained Austenite in the High Strength and Plasticity of Medium Carbon Q&P Steel

The Fe–0.44%C–1.8%Si–1.3%Mn–0.82%Cr–0.28%Mo steel treated by the quenching–partitioning process showed a product of strength and elongation of 30 GPa % with yield stress of 1350 MPa. Such a combination of high ultimate tensile strength and good ductility is attributed to a high portion of retained austenite (≥20%) transforming to martensite under tension. The high yield stress is provided by carbon supersaturation of austenite and a high dislocation density in this phase.