Prediction of nanoindentation hardness profile from a load-displacement curve

During the nanoindentation process, the load and depth data are continuousl y recorded. A single load-displacement curve is thus expected to contain ma terial property information from the whole depth range indented. In the pre sent paper, a new method to obtain the hardness-depth curve has been derive d for small depths from the load-displacement curve measured at a large dep th, based on the assumption that the elastic properties of the indented mat erial can be obtained from the indentation depth. Using this method, hardne ss values can be computed for various small depths from a single load-displ acement curve. From a series of nanoindentation experiments, it has been pr oven that the method can be used on both homogeneous and surface-modified m aterials, such as fused silica, single crystal tungsten, and plasma nitride d steel with and without an iron nitride Fe4N compound layer. Testings on a series of Ni-P films coated on 15 MnB steel also gave fairly good results.