Crystal Plasticity Simulation of the Microstructural Effect in Powder Metallurgy Superalloys under Dwell Fatigue Loading

Abstract

The microstructural effect, including γ’ precipitate morphology and twin grains, of dwell fatigue behavior in a powder metallurgy nickel-based superalloy, was studied using crystal plasticity modeling. Strain rate and dwell sensitivities of 923 K were quantitatively investigated. The strain accumulations, under normal and dwell fatigue loading, showed γ’ precipitate size-dependence. Strong load shedding can be observed between parent and twin grains, which was attributed to local plastic heterogeneity. Local stress and strain evolution are both faster than the macroscopic values, which threatens the safety of engine components.

Keywords

• load shedding
• microstructure
• size effect
• γ’ precipitate
• dwell fatigue