The steel 30CrMnSiNiWMo used in the aircraft industry is studied. The temperature and time ranges of austenite transformation during continuous cooling are established using the dilatometric method. The dilatometric modeling of various modes of quenching–partitioning and austempering heat treatment is carried out. The features of transformations occurring in the studied steel at different stages of the heat treatment are revealed. The analysis of mechanical properties after austempering, quenching–partitioning and oil quenching and tempering is carried out. It is shown that the implementation of isothermal hardening does not lead to the expected increase in the level of mechanical properties of the studied steel. © 2023, The Indian Institute of Metals - IIM.