Thermo-Mechanical Fatigue Cycle Damage Mechanism and Numerical Simulation of GH4169 Superalloy

Under complex cyclic force/thermal multifield coupled service conditions, one of the most common failure types of aeroengine turbine disks is thermo-mechanical fatigue (TMF) failure. In metallurgy, petrochemicals, nuclear energy, aviation, and other industries, the GH4169 superalloy is frequently used. To further enrich the fatigue performance data of this alloy, in-phase (IP) and out-of-phase (OP) TMF tests were conducted on the nickel-based superalloy GH4169 at 0.6% and 0.8% strain amplitudes with temperature cycling from 350 degrees C to 650 degrees C. The TMF hysteresis loops, cyclic stress response behavior, fatigue crack initiation, propagation behavior, and fatigue life were analyzed. The experimental results show that the TMF stress-strain curves show tensile-compression stress asymmetry, and there is obvious cyclic softening in the high-temperature half-cycle. The TMF life is shorter than the isothermal fatigue life at the peak temperature under the same strain amplitude. Moreover, the increase of strain amplitude leads to the increase of cyclic deformation and reduces the fatigue life. The fracture analysis and the results show that the OP TMF cracks display transgranular fracture, while the IP TMF cracks show intergranular fracture. Finally, the TMF cyclic deformation behavior was simulated using the Chaboche visco-plastic model, and the simulation results were consistent with the experimental results, reflecting the basic characteristics of TMF.