Abstract:To address the lack of service performance evaluation of the extruded and forged FGH95 alloy under the service conditions of the aero-engine powder-disc components, a feature-base specimen based on the maximum principal strain gradient on the retaining groove of the powder-disc component were designed according to certain design criteria, and the design method was verified. Then, the fatigue life method based on the theory of critical distance (TCD) was employed to predict the service life. Finally, the fatigue life method and failure mechanisms were validated. The results show that the three-dimensional spatial domain automatic search method proposed in the present study can obtain the maximum principal strain gradient on the retaining groove. Compared with the Morrow-modified total strain life method commonly used in engineering, the TCD-life method incorporating the strain gradient can more accurately predict the fatigue life of the retaining groove. The important reason why the standard notched round bar specimen cannot accurately predict the fatigue life of the retaining groove is reasonably explained. The differences in the fatigue failure mechanisms of the standard notched round bar specimen, retaining groove, and its feature-base specimen are verified by fracture analysis techniques.