Effect of Different Isothermal Time on Microstructure and Mechanical Property of the Low-Carbon Steel Treated by Dual-Stable C-Mn Partitioning Process

The stability of retained austenite was improved by the dual-stable C-Mn partitioning process. The phase transformation and element diffusion of dual-stable C-Mn partitioning process of tested steel were investigated by means of EPMA, SEM, OM, tensile testing machine, and other analysis methods. The effects of the first and second austenite stabilization time on the microstructure and mechanical properties of low-C-Si-Mn steel were studied, respectively. The enrichment of C and Mn elements is obvious after the dual-stable C-Mn partitioning process, and the microstructure of the tested steel is constituted of martensite, ferrite, and retained austenite. Compared with the conventional Q&P steel, the tensile strength of the steel treated by the dual-stable C-Mn partitioning process is slightly lower, but the plasticity is improved significantly. The tensile strength is 875-910 MPa, the elongation is 20-24%, and the product of strength and elongation can reach 21 GPa·%.