The cyclical crack resistance of power-plant steels is studied. The influence of metal condition (properties) within a specific steel grade on the characteristics of cyclical crack resistance is analyzed. It is shown that, at a room temperature, i.e., in the range of viscous-brittle transition, the cyclical crack resistance of steel decreases with the increase in its tendency to the brittle state. With increasing temperature from room to 300-320°C, the cyclical crack resistance steel decreases, and for state-specific conditions, the degree of fatigue crack growth correlates with the level of yield strength decrease at the same temperature. Taking this into account, the approach to approximation of the kinetic cyclical crack resistance diagram is experimentally proved by a generalized dependence invariant to temperatures in the range 20-300 (320)°C. [ABSTRACT FROM AUTHOR]