Microstructure and mechanical properties of a novel hot-rolled 4% Mn steel processed by intercritical annealing
The study described here focuses on the microstructure and mechanical properties of a novel hot-rolled medium-Mn steel (Fe–0.25C–4Mn–1.88Al–0.6Si–0.04Nb–0.08V, wt%) that contained only 4 wt% Mn and modest Al content of 1.88 wt%. It was found that a relatively high content (25–53 vol%) of retained austenite was obtained by intercritical annealing process. With increase in intercritical annealing temperature from 700 to 740 and to 760 °C, retained austenite fraction increased from 25.1 to 53.2% and then decreased to 46.1%. Besides, mechanical stability of retained austenite in 700–760 °C intercritically annealed steels decreased with increase in intercritical annealing temperature. The 720 °C intercritically annealed steel yielded excellent mechanical properties with yield strength of 766 MPa, tensile strength of 951 MPa, total elongation of 48.6% and PSE of 46.22 GPa·%, achieved by a high volume fraction of retained austenite (46%) with relatively high mechanical stability. Thus, the 4% Mn steel present in this study indicated excellent mechanical properties of medium-Mn steels can be achieved using low alloy content.
The authors acknowledge support from the National Natural Science Foundation of China (No. 51504063) and the Fundamental Research Funds for the Central Universities (N170706002, N160706001). R. D. K. Misra also gratefully acknowledges continued collaboration with the Northeastern University as honorary professor providing guidance to students in research.
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Conflict of interest
The authors declare that they have no conflict of interest.
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