  The effect of slip transfer on the flow strength of various FCC polycrystals
was analyzed by means of computational homogenization of a representative
volume element of the microstructure. The crystal behavior was governed by a
physically-based crystal plasticity model in the framework of finite strains
where slip transfer at grain boundaries was allowed between slip systems
suitably oriented according to geometrical criteria. Conversely, slip transfer
was blocked if the conditions for slip transfer were not fulfilled, leading to
the formation of dislocation pile-ups. All the model parameters for each
material were identified from either dislocation dynamics simulations or
experimental data from the literature. Slip transfer led to a reduction in the
flow stress of the polycrystals (as compared with the simulations with opaque
grain boundaries) which was dependent on the fraction of translucent and
transparent grain boundaries in the microstructure. Moreover, dislocation
densities and Von Mises stresses were much higher around opaque grain
boundaries, which become suitable places for damage nucleation. Finally,
predictions of the Hall-Petch effect in Al, Ni, Cu and Ag polycrystals
including slip transfer were in better agreement with the literature results,
as compared with predictions assuming that all grain boundaries are opaque,
particularly for small grain sizes ($<$ 20 $\mu$m).
