High-strength low-density steels are strongly recommended in the automotive industry because they can reduce weight and CO₂ emissions without affecting structural safety. In this study, a novel Cr-alloyed austenitic steel with a low density of 6.50 g/cm³ was designed. It was subjected to two types of processing routes. One includes cold rolling with a thickness reduction of 35% followed by aging at 450 ^oC for 1.5 h (known as 35CR-T). The other route includes cold rolling by 75%, short annealing at 925 ^oC for 10 s, and final aging at 450 ^oC for 1.5 h (known as 75CR-AT). Both resultant specimens exhibited excellent tensile properties; the specific yield strength and total elongation of the 35CR-T and 75CR-AT specimens reached 211.5 MPa·cm³/g, 15.6% and 210.0 MPa·cm³/g³, 21.5%, respectively. The microstructure of the former comprises relatively coarse austenite grains with high-density dislocations as the matrix and coarse κ-carbides, whereas that of the latter comprises fine recrystallized austenite grains and more extensive intragranular κ-carbides with a finer size. Consequently, greater dislocation strengthening contributes to the yield strength (YS) of the former, whereas more significant grain refinement and precipitation strengthening contribute to the YS of the latter. Therefore, both specimens have the same YS after considering all strengthening contributors. Moreover, the recrystallized austenite grains in 75CR-AT allow the sequential evolution of the dislocation substructure from planar-slip dislocations, Taylor lattice, and high-density dislocation wall to the microband during tensile deformation. By contrast, the dislocation microbands formed in the austenite grains of 35CR-T specimen suppress the dislocation multiplication and sequential evolution of dislocation substructures, resulting in poorer ductility compared with that of 75CR-AT specimen.