Flow stress and microstructures of fine grained copper

For a fine grained pure copper (grain size, 3.8 μm) with a weak initial texture, the flow stress and the microstructure have been examined. The stress–strain curve has been compared with that of a coarse grained copper with a weak texture and a similar curve shape has been found, indicating no change in the strain hardening behavior as the grain size is decreased. The validity of the Hall–Petch relationship has been demonstrated down to a grain size of 3.8 μm. Careful microstructural characterization of deformed specimens has shown that the microstructural evolution in the fine grained copper follows the same pattern previously established for larger grain sizes, which is characterized by the formation of three types of microstructures depending on the grain orientation. This observation suggests that the slip patterns in the fine grained and coarse grained copper are comparable, which underpin the observation of a comparable stress–strain behavior.