高强低密度钢能在保证结构安全性的前提下降低重量，减少CO₂排放，因此在汽车等交通运输工业中占有重要的地位。本工作设计并制备出一种密度为6.50 g/cm³的含Cr奥氏体钢。经35%压下率冷轧+时效 (35CR-T)和75%压下率冷轧+退火+时效(75CR-AT) 2种工艺路径所得到的样品均表现出优异的综合力学性能，2者的比屈服强度和总延伸率分别达到211.5 MPa·cm³/g、15.6%和210.0 MPa·cm³/g、21.5%。其中，35CR-T样品的显微组织由具有高密度位错的奥氏体和粗大的κ-碳化物组成；75CR-AT样品的显微组织由细小的再结晶奥氏体和更多、更细小的晶内κ-碳化物组成。因此，前者位错强化贡献值更高，而后者晶界强化和析出强化增量更高，这导致2种样品屈服强度相当。75CR-AT样品中再结晶奥氏体变形时依次形成平面滑移位错、Taylor晶格、高密度位错墙和微带等位错亚结构，而35CR-T样品中奥氏体内的微带结构限制了其变形时位错增殖和位错亚结构的形成，因此后者的塑性较前者差。

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.