Indentation hardness: Fifty years on - A personal view

This introductory paper is a brief revised account of basic studies carried out between 1940 and 1946 on the meaning of indentation hardness. Using very simple concepts, it shows that the indentation hardness of metals is directly related to the uniaxial yield stress as augmented by the deformation and work hardening produced by the indentation process itself. The work originally carried out on metals is applicable to many other solids, particularly if they have a crystalline structure. The paper concludes with a short review of current studies in the field of microhardness and nanohardness.