ESTIMATION OF HARDNESS BY NANOINDENTATION OF ROUGH SURFACES

The roughness of a surface influences the surface mechanical propertie s, estimated using nanoindentation data. Assuming a relation between t he penetration depth normalized with respect to a roughness scale para meter, and the effective radius encountered by the indenter, a first o rder model of roughness dependency of hardness is proposed. The practi cal usefulness of this model is verified by the numerical simulation o f nanoindentation on a fractal surface. As the roughness of a surface is increased, the hardness measured at depths comparable with the roug hness scale deviates increasingly from the actual hardness. Given the constants related to indenter geometry, the present work provides a ra tionale and a method for deconvoluting the effect of roughness in arri ving at real hardness characteristics of the near surface region of a material.