On deriving vickers hardness from penetration depth

It is proposed to approach the problem of deriving hardness from load versus penetration depth curves by the tentative assumption of constant hardness, combined with a simple theoretical mode (evenly loaded square on elastic half-space). This suggests to do three corrections: separating the elastic displacement from the recorded depth, redefining the zero of depth, and discarding an initial section of the penetration curve. Comparison with experiment seems to indicate that the hardness numbers obtained in this way get close to the conventional Vickers (micro)-hardness.