Computational simulation has become more important in the design of thermomechanical processing since it allows the optimization of associated parameters such as temperature, stresses, strains and phase transformations. This work presents the results of the three-dimensional Finite Element Method (FEM) simulation of the hot rolling process of a medium Mn steel using DEFORM-3D software. Temperature and effective strain distribution in the surface and center of the sheet were analyzed for different rolling passes; also the change in damage factor was evaluated. According to the hot rolling simulation results, experimental hot rolling parameters were established in order to obtain the desired microstructure avoiding the presence of ferrite precipitation during the process. The microstructural characterization of the hot rolled steel was carried out using optical microscopy (OM), scanning electron microscopy (SEM) and X-ray diffraction (XRD). It was found that the phases present in the steel after hot rolling are austenite and α′-martensite. Additionally, to understand the mechanical behavior, tensile tests were performed and concluded that this new steel can be catalogued in the third automotive generation.

A novel medium-Mn steel microstructure with 0.1 wt.% Nb was designed using Thermo-Calc and JMatPro thermodynamic simulation software. The pseudo-binary equilibrium phase diagram and time–temperature transformation (TTT) and continuous cooling transformation (CCT) diagrams were simulated in order to analyze the evolution of equilibrium phases during solidification and homogenization heat treatment. Subsequently, the steel was cast in a vacuum induction furnace with the composition selected from simulations. The specimens were heat-treated at 1200 °C and water-quenched. The results of the simulations were compared to the experimental results. The microstructure was characterized using optical microscopy (OM) and scanning electron microscopy (SEM). We found that the as-cast microstructure consisted mainly of a mixture of martensite, ferrite, and a low amount of austenite, while the microstructure in the homogenization condition corresponded to martensite and retained austenite, which was verified by X-ray diffraction tests. In order to design further production stages of the steel, the homogenized samples were subjected to hot compression testing to determine their plastic flow behavior, employing deformation rates of 0.083 and 0.83 s⁻¹, and temperatures of 800 and 950 °C.

This research is focused on the development of a novel medium Mn steel with V-addition (0.14 wt.%), which belongs to the Advanced High Strength Steels (AHSS). In order to predict the equilibrium phases, thermodynamic simulation was used. The microstructure of the as-cast steel was composed of retained austenite, α´-martensite/α-ferrite and a very small amount of ɛ-martensite. To understand the hot flow behaviour of the as-cast steel, hot compression tests were performed at 800°C and 1000°C with a strain rate of 0.83 s⁻¹ and 0.083 s⁻¹, the results were compared to a V-free steel taken from the literature. A significant increase in the applied stress was observed in the samples deformed at 800°C, especially, at the strain rate of 0.083s⁻¹. Finally, to achieve a better understanding of this behaviour, the microstructure of the V-added steel was studied after hot compression tests.

Medium Mn steels have gained significant attention for their potential to achieve exceptional combinations of strength and ductility through controlled microstructural engineering, and intercritical annealing is recognized as a key processing route to optimize austenite formation and mechanical properties in these alloys. However, the precise relationship between annealing parameters and resulting microstructural evolution in medium Mn steels remains inadequately understood, particularly regarding the optimal conditions for achieving superior mechanical performance. Therefore, this study systematically investigated the microstructural development of 7 wt.% Mn steel during controlled hot-rolling and intercritical annealing to establish processing-structure-property relationships. Hot-rolling produced predominantly lath martensite microstructure with minimal austenite presence. Intercritical annealing was conducted at 700°C and 780°C for 1, 2, and 5 h, resulting in ferrite/martensite and austenite microstructures with austenite content ranging from 10 to 25 wt.%. NbC precipitates were identified after electrochemical extraction. On the other hand, samples annealed at 700°C demonstrated optimal mechanical properties in terms of ultimate tensile strength and elongation, while both hot-rolled samples and those treated at 780°C exhibited brittle behavior with low elongation. These findings establish that intermediate annealing temperatures provide the most favorable microstructural balance for achieving superior mechanical performance in medium Mn steels.