The localization of plastic flow under dynamic indentation conditions: I. Experimental results

In the present study, the response of four metallic materials indented under both static and dynamic indentation conditions using spherical balls has been compared. In particular, the hardness-average strain behaviour, the shape and extent of lip formation around the periphery of indentation and the size of the plastic zone formed around the indentation in the material being indented have been obtained under both static and dynamic indentation conditions. The results clearly indicate that as compared to static indentation conditions, the hardness behaviour under dynamic indentation conditions is unusual in the sense that it goes through a maximum as a function of average strain in the case of iron, steel 260 and Al7039 samples. Further, evidence for enhanced lip formation under dynamic indentation conditions has been obtained, pointing to some form of localization of plastic flow underneath the impacting ball unlike in the case of static indentation.