A subregular solution thermodynamic model was employed to calculate the stacking fault energy (SFE) in Fe–Mn–Al–C–Si steels with contents of carbon 0.2–1.6 wt.%, manganese 1–35 wt.%, aluminum 1–10 wt.%, and silicon 0.5–4 wt.%. Based on these calculations, temperature-dependent and composition-dependent diagrams were developed in the mentioned composition range. Also, the effect of the austenite grain size (from 1 to 300 μm) on SFEs was analyzed. Furthermore, some results of SFE obtained with this model were compared with the experimental results reported in the literature. In summary, the present model introduces new changes that shows a better correlation with the experimental results and also allows to expand the ranges of temperatures, compositions, grain sizes, and also the SFE maps available in the literature to support the design of Fe–Mn–Al–C–Si steels as a function of the SFE.

During the last years, the scientific and industrial community have focused on the astonishing properties of Fe-Mn-Al-C steels. These high advanced steels allow high-density reductions about ~18% lighter than conventional steels, high corrosion resistance, high strength (ultimate tensile strength (UTS) ~1 Gpa) and at the same time ductility above 60%.The increase of the tensile or yield strength and the ductility at the same time is almost a special feature of this kind of new steels, which makes them so interesting for many applications such as in the automotive, armor and mining industry. The control of these properties depends on a complex relationship between the chemical composition of the steel, the test temperature, the external loads and the processing parameters of the steel. This review has been conceived to tried to elucidate these complex relations and gather the most important aspects of Fe-Mn-Al-C steels developed so far.

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