Study on Fatigue Properties of Turbine Disk Groove Modeling Specimens of GH4720 Alloy

Based on the structural features and the work status of the aero-engine turbine disk groove, the experimental and theoretical analysis of the fatigue failure mechanism and the crack growth life of the groove modeling specimen of GH4720 alloy were carried out. The fatigue failure of the groove modeling specimen of GH4720 alloy can be divided into three stages: (i) due to the high stress concentration, slip systems are activated and then cracks initiate; (ii) with the increase of loading cycles, adjacent intergranular dislocations and slip systems are activated, cracks transfer between grains; (iii) with the increase of the stress intensity factor range and the cooperation of shear stress and principal stress, the dislocations motion in different slip systems and the crack propagation are accelerated. A fatigue crack growth life model of GH4720 alloy has been established. The crack growth lives obtained from the finite element analysis and the life model have a good agreement with the results of the experiment. It is demonstrated that the life model can be used in engineering to predict the remaining life of turbine disk.