Measurement of mechanical properties of 1045 steel with significant pile-up by sharp indentation

Abstract

The Oliver–Pharr method has extensively been adopted for measuring hardness and elastic modulus by indentation techniques. However, the method assumes that the contact periphery sinks in, which limits the applicability to the materials pile up. This study proposed an improved methodology to calculate the real contact area of 1045 steel with significant pile-up. The contact boundary between indenter and specimen was assumed to overlap with the top points on the residual surface profile, and the real contact depth was defined by a sum of the indentation depth at maximum load, hmax, and average pile-up height, \( h_{\text{pile - up}}^{\text{ave}} \), measured from the analysis on the residual indent morphology with atomic force microscope (AFM). The mechanical properties calculated by the newly proposed method were compared with those by the Oliver–Pharr method.