## 1 Introduction  
The need to minimize fuel consumption in automobile engines and ultimately reduce greenhouse gas emissions contributed by the transportation industry has resulted in the development of a wide range of light alloys with high specific strength and crashworthiness. Low-density steels remain one of the light alloys that have received significant attention from researchers in the last decade owing to their attractive combination of properties, such as high strength, good balance between ductility and toughness, good fatigue strength, good oxidation and corrosion resistance, and high energy absorption under impact loading [1, 2]. These outstanding mechanical properties could benefit a whole range of other industries, such as the cryogenic and construction industries. This is because different property combinations can be obtained in low-density steels by manipulating process parameters and microstructural control [3]. The different property combinations exhibited by low-density steels were accomplished by adding lightweight elements such as Al, Ti, Si, and C into the Fe-Mn alloy system, reducing the density and increasing the strength-to-weight ratio [2]. The alloying elements in low-density steels yield various microstructures that either complement the material's integrity if added in the right amounts or degrade it when added in excess [3]. For example, the presence of Mn in high amounts promotes the stability of the preferred austenite phase. In addition, the presence of other alloying elements such as Al, Cr, and C in controlled amounts precipitates intragranular carbides, such as K-carbides, M\({}_{23}\)C\({}_{6}\), M\({}_{7}\)C\({}_{3}\), and M\({}_{3}\)C, which are responsible for the different strengthening mechanisms observed in these alloys [2; 4; 5]. However, with high Al content (>9%), a disordered ferrite containing ordered B2 and DO3 phases is likely to nucleate along the grain boundaries, and these phases embrittle low-density steels [3]. Furthermore, high Al and C additions may result in the formation of intergranular K-carbides that also reduce the ductility of low-density steels. Of all the alloying elements in low-density steels, Al is considered the most important as it yields a \(\sim\)1.3% reduction in density per one weight present (wt%) of Al, but the elastic modulus reduces considerably with increasing Al content [1; 3; 4]. Owing to the sensitivity of low-density steels to slight compositional changes, there have been considerable research efforts on phase calculation and alloy development to understand the formation of phases and how they influence the properties of the different grades of low-density steels. These research efforts have led to classifying low-density steels based on their microstructural constituents [3; 4]. Typical microstructures of low-density steels have matrices that can be austenitic (\(\gamma\)), ferritin (\(\alpha\)), or duplex (\(\alpha+\gamma\)). Precipitates of different carbides can also form in the matrices depending on the constituent elements, their amount, and processing conditions [3]. The most promising low-density steel is the austenitic Fe-Mn-Al-C type owing to its excellent combination of properties [4]. Consequently, more attention has been given to this grade of low-density steels. In 2020, [PERSON] et al. [5] developed new grades of austenitic low-density steels by adding different amounts of Cr into the conventional Fe-Mn-Al-C system. They found that \(\sim\)5 wt% Cr was optimum to yield high ductility without significantly compromising strength. These alloys also exhibited a superior pitting potential in 3.5 wt% NaCl medium compared to conventional stainless steels. These Cr-bearing low-density steels were dubbed low-density stainless steels [5].