New high-nitrogen austenitic 0Kh21A1 and 0Kh18N2A1 alloys are subjected to stress-corrosion cracking (SCC) tests in a 20% NaCl solution. The alloys are studied by fractography, dilatometry, and X-ray diffraction before and after the SCC tests (their fracture surfaces are studied). The nickel-free alloy is found to have higher strength and SCC resistance. Both alloys exhibit the minimum SCC resistance after aging at 350°C. Our studies have shown that the chemical inhomogeneity of the initial austenite in the 0Kh21A1 and 0Kh18N2A1 alloys is the main cause of the formation of martensite of different compositions and morphology during both cooling and deformation. The SCC of the alloys under study is thought to be controlled by the γ → α martensite transformation of a nitrogen-rich austenite during deformation.