The work aims to investigate the effect of different annealing temperatures on the microstructure and mechanical properties of the medium-manganese steel in 10Mn system, so as to determine the optimal annealing parameters for achieving the best comprehensive performance. Experimental steels were prepared through vacuum melting, solution treatment, hot rolling, and annealing at various temperatures. Microstructural characterization was performed through scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and X-ray diffraction (XRD). Mechanical properties were evaluated by means of uniaxial tensile testing. As the annealing temperature increased, the microstructure evolved from the as-rolled lath morphology into a dual-phase equiaxed structure consisting of ferrite and austenite. The volume fraction of the austenite continuously increased with the temperature, reaching 19%, 38.9%, and 41.5% at 600, 650, and 700 ℃, respectively. In contrast, the average carbon content of the austenite firstly increased and then decreased, peaking at 650 ℃. Tensile tests indicated that the sample annealed at 650 ℃ exhibited the optimum comprehensive mechanical properties, with yield strength, tensile strength, and elongation reaching 801 MPa, 1 012 MPa, and 54.6%, respectively. Annealing at 650 ℃ results in an optimal balance between the volume fraction and stability of the austenite. During deformation, this condition promotes a sustained transformation-induced plasticity (TRIP) effect, which enhances strain hardening and improves plastic compatibility. As a result, an excellent product of strength and elongation (PSE) of 55.2 GPa·% is achieved, demonstrating outstanding strength-ductility synergy.
Key words
medium-Mn steel /
intercritical annealing /
microstructure /
mechanical properties /
carbon content
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Funding
Science and Technology Research Project of Jiangxi Provincial Department of Education (GJJ2204811); Basic Research Project of Jiujiang (2025_001332)
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