Deformation mechanism maps plotted for a 1CrMoV steel were used to describe damage formation under high temperature cyclic-hold test conditions. A grain boundary sliding regime was used to indicate the onset of wedge crack formation. Strain rate transitions bounding the regimes of known dominant damage mechanism were subsequently evaluated for temperatures in the range 450 – 650 °C. These transition strain rate concepts were incorporated into a ductility exhaustion approach to life prediction. The transitions enabled an accurate demarcation to be made between the creep and fatigue damage processes. Cyclic life predictions obtained using the ductility exhaustion approach for a range of cyclic-hold tests on the 1CrMoV steel at 565 °C yielded excellent correlation with observed behaviour.