1. Martensitic chromium-nickel stainless steels quenched and then tempered at a low temperature contain a considerable amount of austenite which is transformed into martensite on cooling to −70°C. 2. The amount of residual austenite in these steels increases (up to 40–50%) if the steels are tempered at 350°C after quenching in warm oil (100–150°C). 3. Stresses of 30–40 kg/mm2 intensify the γ→α-transformation