Influence Mechanism of Inclusion Size on Low Cycle Fatigue of Powder Metallurgy Superalloy

To study the effect of inclusion size on the low cycle fatigue life of powder metallurgy superalloy, the stress distributions at the same locations (center, subsurface and surface) were analyzed by finite element simulation. The calculation results show that when the inclusion/matrix interface does not contain the microhole, and the inclusion and matrix size proportion in a laboratory scale (1:25) to the project scale (1:10 000), the inclusion effect on stress and strain is very small. The influence of defects on the fatigue life is mainly due to the larger the inclusion size, the greater the interface between the substrate and the matrix is, the probability of imperfect connections and defects will increase, which will lead to initial damage at the interface.When the inclusion/matrix interface containing microholes, as the inclusion size bigger, interface normal stress increases obviously, interface shear stress decreases weakly, and the matrix maximμm normal stress and maximμm plastic strain are significantly increased. The influence mechanism of inclusion size on low cycle fatigue property should be that the interface of inclusion/matrix often contains microholes.