State primary standard machine on Vickers and Knoop hardness scales GET 31-2024

The results of research aimed at ensuring the uniformity of hardness measurements according to the Vickers and Knoop scales, reproduction of Vickers hardness numbers HV in the range 2000–5000 and Knoop hardness numbers HK in the range 17–2500. The research is due, firstly, to the fact that the hardness of ceramics used in industry and medicine is more than 2000 HV, and hardness measurements on the Vickers scales of products made of these ceramics were not traced to the State primary special standard for metal hardness on the Vickers GET 31-2010 scales. Secondly, the Vickers tip print has a square shape, therefore, when measuring hardness on a limited area of the surface, for example near a weld, one of the corners of the print goes beyond the boundaries of the measured zone, which leads to an incorrect assessment of the hardness of the studied surface area. The Knoop method, implemented using a tip, the base of which is made in the form of a diamond with one short side, solves the problem of correct hardness testing on a limited area of the surface. A reference installation has been investigated and included in the State primary hardness standard according to the Vickers and Knoop scales GET 31-2024, which allows reproducing the Vickers hardness numbers HV in the range 2000–5000 and the Knoop hardness numbers. Thus, the traceability of measurement results obtained using hardness testers to GET 31-2024 is ensured. The metrological characteristics of GET 31-2024 have been studied. The use of hardness testers traceable to GET 31-2024 makes it possible to accurately assess the mechanical properties of new materials, predict the performance characteristics of products made of new materials, and increase the reliability of product hardness control.

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