Effect of damage in service of 12Kh1MF steam-pipe steel on its crack resistance characteristics

The results of investigations of the effect of long-term service of steel on the characteristics of its static cyclic crack resistance are presented. The kinetic diagrams of fatigue failure for the whole range of fatigue crack rates (from the rates close to the threshold of 10−10 m/cycle to 10−3 m/cycle) are analyzed. It is shown that acceleration of fatigue crack growth as a result of a change in the state of the metal in service is most pronounced in the third and threshold regions of the effective kinetic diagrams of fatigue failure. The observed regularities are explained by structural transformations in the metal of a steam line under the effect of service factors.