Hardness scale maintenance in Italy

The work carried out by the IMGC for hardness-scale realization, maintenance, improvement and dissemination is aimed, essentially, at establishing an appropriate system of hardness measurement traceability available to the national and foreign industry. Industrial requirements have been getting increasinlingly stringent, so that it is necessary, on the one hand, to continue improving standards and, on the other, to modify the norms defining hardness scales, to make them adequate to requirements. Standardization becomes critical when hardness scales must be correctly defined from a metrological standpoint and, at the same time, be suitable from the viewpoint of industrial needs. The different Quality Systems of industrial concerns involve, to an increasing extent, the determination of materials hardness, to serve as a production testing tool. It is required that the hardness test duration be as short as possible, but this contrasts with metrological exigencies, since in hardness tests, which have a very important dynamic effect, measurements must be carried out under the most stable conditions, which consequently need relatively long times. Much work is expected for norms preparation; for this reason IMGC takes part in all international and European meetings and promotes the establishment of ad hoc working groups. Obviously, for the maintenance and the improvement of its hardness scales IMGC has established a programme of comparisons with the scales maintained by the national standards laboratories of several countries in Europe and elsewhere /1/. In this way, scales can be regularly checked and, which is also very important, it is possible to observe the effects of modifications in the relevant norms on overall measurement uncertainty. One important action IMGC undertook- some years ago, was cooperative work for the development of hardness scales in countries where work had been until then exclusively entrusted to industrial concerns. In our opinion, the correct realization of hardness scales based on the standards of force, time and length is as important for measurement quality as a correct traceability system is for scale dissemination to the industry. The most important cooperation has been that of IMGC and NIST, which equipped its laboratory with a hardness standard machine designed by IMGC. This cooperation allows both laboratories to improve their hardness standards. Other cooperation programmes are being carried out in other extra-European countries, to provide consultancy for the establishment of an efficient traceability system; in future, cooperation is likely to include the construction of other standard machines.