From internal strength analysis by drilling to the hardness profile determination of a superficially heat-treated steel

The thrust measured during a drilling test is related to the hardness of th e material tested. When the test is performed on a superficially heat-treat ed specimen, the results do not exactly correspond to the hardness profile obtained by the Vickers micro hardness technique. The difference is due to the integration of heterogeneous resistance along the cutting edge of the c onic dr ill. By discretising the drilled thickness, we have developed an al gorithm yielding the hardness of each elemental thickness. Results are very close to those obtained by Vickers hardness profile measurements. (C) Acad emie des sciences/Elsevier Paris.