Enhanced Stability of Retained Austenite by Quenching and Double Partitioning Process

Abstract

In the present study, a novel quenching and double partitioning (Q&DP) process is proposed. The quenching and partitioning (Q&P) process was accompanied by a second partitioning process, which led to the enhanced stability of retained austenite. The chemical composition of the investigated steel was 0.24C-1.9Mn-1.85Si, without an excess addition of alloying elements. This process aims to enhance the stability of retained austenite by controlling martensitic transformation and carbon partitioning. By applying this process, the uniform and total elongation is increased, without obvious reduction in ultimate tensile strength. An optimum combination of strength and ductility (ultimate tensile strength: 1304MPa; total elongation: 23%) was achieved by quenching to 65°C and subsequent second partitioning treatment, after the first quenching to 300°C and partitioning process. The enhanced mechanical properties were attributed to the increased amount of stabilized film-like austenite.