# Grain boundary strengthening of FCC polycrystals

## TL;DR

This study uses computational homogenization with a dislocation-based crystal plasticity model to analyze how grain size influences the flow strength of FCC polycrystals, validated against experimental data for multiple metals.

## Contribution

It introduces a physically meaningful crystal plasticity model that links grain size to flow strength through the similitude coefficient, validated with experimental results.

## Key findings

- Grain size affects flow strength mainly via the similitude coefficient K.
- Model accurately predicts flow strength for Ni, Al, Cu, and Ag.
- Dislocation pile-ups at grain boundaries are key to understanding strengthening.

## Abstract

The effect of grain size on the flow strength of FCC polycrystals was analyzed by means of computational homogenization. The mechanical behavior of each grain was dictated by a dislocation-based crystal plasticity model in the context of finite strain plasticity and takes into the account the formation of pile-ups at grain boundaries. All the model parameters have a clear physical meaning and were identified for different FCC metals from dislocation dynamics simulations or experiments. It was found that the influence of the grain size on the flow strength of FCC polycrystals was mainly dictated by the similitude coefficient $K$ that establishes the relationship between the dislocation mean free path and the dislocation density in the bulk. Finally, the modelling approach was validated by comparison with experimental results of the effect of grain size on the flow strength of Ni, Al, Cu and Ag.