Low Cycle Fatigue Behavior of a Superalloy GH3030 at Elevated Temperature and Different Strain Ratios

The total strain-controlled low cycle fatigue (LCF) experiment of a nickel-base superalloy GH3030 at 600 ℃ were performed, and the stress-strain hysteresis loop, cyclic stress response, strain amplitude-life and LCF fatigue fracture morphology at different strain ratios (R=-1,0.1)were studied. The results show that the alloy representd cyclic hardening at high strain level while representd cyclic softening initially and then cyclic hardening at low strain level. The difference of the fatigue life at different ratios was not obvious because of the shape of hysteresis loop was adjacent, and tyre-like pattern existed at the crack propagation area on fatigue fracture at different strain ratios.