The deformation and fatigue characteristics of 1Cr-1Mo-0.25V steel cycled at room temperature and an elevated temperature

Cr-Mo-V rotor steel has been cycled to failure with and without tensile holds over a wide range of high strain amplitudes and at both room temperature and 823 K. The damage mechanisms have been examined by scanning electron microscopy observations of the gauge surfaces, of sections and of the fracture surfaces. The fatigue life in continuous cycling is not affected by temperature at the relatively high strain rate used but cycling with hold acts to reduce the life to crack initiation and also accelerates crack propagation. Much evidence of creep damage, including grain boundary cavitation, wedge-type cracking and cavitation at MnS inclusions, has been found, being promoted by high strain amplitudes and tensile holds. However, the life is dominated by fatigue mechanisms which seem to ignore the creep-type damage for the straining conditions used here.