Microstructure-sensitive weighted probability approach for modeling surface to bulk transition of high cycle fatigue failures dominated by primary inclusions

A case study is presented whereby the surface initiation probability is studied in uniaxial strain-controlled cyclic loading simulations of round smooth specimens of the fine grained powder metallurgy (PM) processed Ni-base superalloy IN100. The fatigue crack initiation potency of partially-debonded nonmetallic inclusions is assessed by calculating the Fatemi-Socie (FS) critical plane parameter from generalized plain strain crystal plasticity finite element simulations. Idealized spherical ceramic inclusions with homogeneous linear elastic isotropic material properties are considered to isolate the FS parameter sensitivity to inclusions' size, stress amplitude, and polycrystalline microstructure realization around the inclusion.