Fatigue crack growth rates (FCGRs) of stainless steelin high temperature, high purity water are known to besensitive to cycle time and corrosion rates. An ongoingprogram is aimed at developing a physically-based,environmentally sensitive plasticity model for improvedpredictions of corrosion FCGRs in stainless steel withvarying cycle times. This multi-scale modeling programtakes both top-down and bottom-up approaches rangingfrom density functional theory (DFT) calculations to amacroscale phenomenological low cycle fatigue (LCF)fatigue crack growth (FCG) (LCF-FCG) model. The LCFFCGmodel identifies material properties needed toaccurately reproduce FCGR test data which are elucidatedby a dislocation dynamics-based crystal plasticity (CP)model. Crack tip transmission electron microscopy (TEM)micrographs of the dislocation structure provide thegroundwork for the physical basis of the CP model. The CPmodel is updated using results from dedicated dislocationdynamics (DD) and atomistic simulations, where the DDsimulations provide a basis for the evolution of theassumed CP dislocation structures. A new atomic potentialfor Fe-Ni-Cr-H was created from DFT calculations for thiswork, and atomistic simulations have been used to providemechanistic insights to the CP model as well as prescribingthe associated energetics.
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