Fatigue Crack Growth Life Assessment for Ni-Based Superalloy- Alloy-247LC at Elevated Temperatures

In this study, the high-temperature fatigue crack growth (FCG) life of Alloy-247LC, a polycrystalline Ni-based superalloy manufactured by vacuum investment casting, was evaluated. The FCG rate test was conducted on a C(T) specimen with a thickness of 12.7 mm and a width of 50.8 mm, using the OK-increasing test method for temperatures ranging from room to 800 degrees C. The load was applied to the specimen at a constant load ratio of 0.1 (P-min /P-max ) with a 30 Hz sinusoidal waveshape. The experimental data were analyzed using the modified Paris' law, which reflects the temperature effect by introducing the Arrhenius law, thereby obtaining a high-temperature FCG life assessment equation for Alloy-247LC. The results based on this equation showed that all experimental data were distributed within the limit of two times the average line. The reliability of this equation was further confirmed by the close correspondence between the measured and calculated FCG rate data.