Multiscale modeling of transgranular short crack growth during fatigue in polycrystalline metals.

Graphical abstract Highlights • Resistance of CTB to dislocation slip was quantitatively evaluated by MD simulations. • Discrete dislocation formulation revealed the dependence of microscopic threshold on material nature and loading condition. • A multiscale model was established to describe FCG for short cracks. Abstract An atomistics-informed multiscale modeling approach was proposed to quantify the transgranular short crack growth during fatigue in polycrystalline metals. The approach solved the two scale inconsistency problems of the classical N-R model, replacing the arbitrary materials strength parameter by the atomistically determined ideal shear strength in the evaluation of both the fatigue crack growth (FCG) rate and the corresponding range of short-crack-featured fluctuations, and incorporating atomistically simulated Peierls stress into the discrete dislocation formulation to quantify the microscopic threshold of FCG through explicitly modeling the interactions between dislocations and grain boundaries. The model-predicted FCG results were compared with the experimental FCG data of GH4169 Ni-based superalloy, demonstrating improved predictive capability than the classical N-R model. Our study provides new physical insights and improved predictability towards accurate quantification of the short crack growth in polycrystalline metals. [ABSTRACT FROM AUTHOR]