Correlation between the flow stress and the nominal indentation hardness of soft metals

For the sharp indentation of soft metals, we first reveal a simple relation between the nominal hardness, H-n, and the flow stress, sigma(r), i.e. H-n = 4.4 sigma(r). Further, using the relation proposed herein instead of the well-known Tabor's relation and the analysis performed by Nix/Gao on the geometrically necessary dislocations, a simple indentation nominal hardness-depth relation at the microscale is obtained. The model agrees well with the experiment data in the, literature and the simulation based on a strain gradient theory. (c) 2008 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.