Characteristics of Microscopic Inclusions and their Influence on Fatigue Crack Propagation in FGH96 Superalloy

FGH96 superalloy has been used in aircraft engine turbine discs due to the superior damage tolerance. This work investigated the characteristics of microscopic inclusions and their influence on fatigue crack propagation in hot isostatic pressed and heat treated commercial FGH96 superalloy. Low cycle fatigue crack growth tests were conducted. Several kinds of microscopic inclusions were identified by optical microscope (OM), scanning electric microscope (SEM) and energy dispersive spectrometer (EDS). Microscopic inclusions and secondary cracks were analyzed near the main cracks. Combined with the finite element method (FEM) results, it can be proposed that the microscopic inclusions have no critical influence on fatigue crack propagation in the specimens.