Fatigue-creep behaviors of Ni–Fe based superalloy under various testing conditions

The fatigue-creep properties of Ni–Fe based superalloy with varying strain amplitude, temperature and holding duration are studied in ambient air. The results demonstrated that the number of cycles decreases greatly with increasing strain amplitude from 0.5% to 1.0%, and the <001>ǁRD texture in the microstructure is conformed along the deformation direction. Both high temperature and holding duration are key factors in the reduction of fatigue cycles. It is determined that the dislocations bypass the second phase particles during deformation process, and the critical shear stress transition is observed. Different from the temperature factor, higher holding time leads to the growth of the second phase, and which finally exceeds the critical size of dislocation cutting, leading to the inducement for dislocations bypassing the second phase.