Multi-scale Mechanical Property Strength Analysis

Abstract

The nanoindentation test is the most important method for the evaluation of mechanical properties in ultra-small regions. However, the hardness value in the nano region does not always equal to the macro hardness. The reason is that when evaluating a steel material, the physical properties differ depending on the scale such as the strengthening mechanism of the steel material (dispersion / precipitation strengthening, grain refinement strengthening). In addition, the hardness is affected by the roundness of the indenter tip. Therefore, in order to establish an indentation method for the nano region, we proposed an empirical formula that uses monocrystal metal as a standard sample and converts the indentation depth into hardness. The hardness conversion of this nano region corresponds to the hardness of the macro region. Multi-scale mechanical properties were made possible by plotting hardness on the vertical axis and indentation size on the horizontal axis from the nano region to the macro region. In this paper, we describe the nanoindentation test equipment and the hardness conversion method for the nano region, and introduce examples of multi-scale mechanical characterization.