The κ-Carbides in Low-Density Fe-Mn-Al-C Steels: A Review on Their Structure, Precipitation and Deformation Mechanism

Fe-Mn-Al-C steels exhibit an outstanding combination of strength and ductility, and the addition of aluminum drastically reduces the density of steels. The low density also offers the advantage of lightweight structures compared with other alloys in practical applications. The addition of aluminum leads to an increased probability of kappa-carbide precipitation, which would significantly affect the mechanical properties. This paper aims to review the kappa-carbide in Fe-Mn-Al-C steels, including the structure, elastic and magnetic properties of kappa-carbide, the precipitation mechanism of kappa-carbide involving thermodynamic equilibrium, and the operative deformation mechanism of kappa-carbide that governs the mechanical properties. It is hoped that such a comprehensive summarization of the knowledge of kappa-carbide will be beneficial for the further development of low-density Fe-Mn-Al-C steels.