The localization of plastic flow under dynamic indentation conditions: II. Analysis of results

In this paper, the data from the companion paper has been analyzed within the framework of localization of plastic flow. First, it has been demonstrated that the decrease in Hd beyond the critical strain (ϵc) is the result of the onset of localization of plastic flow in the material being indented and that such a localization is triggered by the decrease in flow stress due to the temperature rise in the plastic zone due to the adiabatic nature of deformation. However, it is further shown that the extent of decrease of Hd with increasing strain (Iˆav) beyond Iˆavc can be explained only if it is additionally postulated that the plastic zone itself shrinks in size with increasing strain. It is then demonstrated through an indirect analysis of the experimental data, that such a shrinkage of plastic zone does occur. Finally, a composite expression for hardness under dynamic indentation conditions has been derived.