Deformation mechanism as a function of applied load under metal microindentation

The purpose of this paper was to estimate the contribution of applied load values to the development of deformation process during the quasi-static microhardness testing. Water pipes of the commercial iron alloys, steel and cast iron of various diameters (O 25–500 mm) were used for the investigation. It was established that H = f(P) curves for the metal samples can be divided into three specific parts (stages). The existence of those stages indicates that microindentation process occurs in polycrystalline metals due to different mechanisms of plastic deformation. They are: (i) the translation slip mechanism (microlevel) for the 1st stage; (ii) translation/rotation slip mechanism (mesolevel) for the 2nd stage; (iii) the crystal behaviour similar to a homogenous solid (macrolevel) for the 3rd stage. It was shown that the coexistence of translation and rotation modes leads to their interaction and brings an important contribution into plasticity and brittleness of polycrystalline metals.