A study of the microstructure and mechanical properties of engineering steels with high hardenability after cooling at different rates from the austenitizing temperature has been carried out. CCT diagrams are constructed and the ranges of the formation of microstructural constituents during continuous cooling are determined. The cooling paths and cooling rates of the samples in various media are experimentally established - industrial oil, still air, a special container filled with cast iron shavings. It is shown that when the experimental cooling path is superimposed on the CCT diagram, it is necessary to take into account the instantaneous cooling rates in different temperature ranges. The effect of cooling intensity on the mechanical properties of steels of different composition has been quantitatively established. It was found that the impact toughness of steels of different alloying systems in different ways depends on the cooling rate.