Steel 30Kh2GSN2VM (VL1) used in the aircraft industry for heavy-duty parts is studied. The temperature and time ranges of the transformation of supercooled austenite under continuous cooling from the temperature of complete austenitization are determined by the method of dilatometry. Different variants of interrupted and isothermal quenching are simulated to establish the special features of the transformations occurring in the steel in different stages of heat treatment. The mechanical properties are analyzed after isothermal and interrupted quenching and after oil quenching and tempering. It is shown that the isothermal quenching and the stage quenching (the quenching-partitioning technology) do not provide the expected stabilization of a considerable content of retained austenite and elevation of the mechanical properties of the steel.