tolerating-cracks-in-ni-cast-parts123(HCF)(HCF)0KK =1 2 3 4 K 100050000 0.5 1180Flaw size [mm]Fatigue resistance [MPa]Fatigue resistance= 6/ a"6" in [MPa. m1/2]Cast nickel materialsHCF behavior of cast nickelmaterials:- Fatigue resitance ca. 180 MPa- Flaw size corresponding to 1mm crack length does not worsen fatigue resistance.- Stress gradients defuse cracks. Flaw size and stress gradients increase the defusing effect. Cast nickel materials can tolerate cracks up to1 mm without fatigue resistance being affected.Micro cavitymiddlel12Stress pattern during bendingStress pattern inthe notch areaMicro cavity largel12Micro cavity= 0l12Decreasing pore influence on HCF strength 0 0.5 Stress gradient11 - 2. 1 l=[1/mm]Cast ironMalleable ironSpheroidal cast iron12l123(HCF)(HCF)0==K<K