Investigation of frequency and waveform effect on the fatigue crack growth resistance of
heat-resistant 12Cr1MoV steel of a thermal power plant header after exploitation is presented. The
studies showed that the crack growth is very non even. The increase of fatigue crack growth rate
was 0.2-0.65 mm. The decrease of loading frequency at 500 C decreases significantly the FCG rate
on the right part of FCG diagram