On the Relation between the Vickers Hardness Numbers and the Face Angles of Pyramidal Indenters

概要

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Vickers hardness numbers of 45 test specimens have been measured by 4 pyramidal indenters with different magnitudes of face angles (angles between opposite faces of pyramids), in order to find the relation between the Vickers hardness numbers Hv and the magnitudes of the face angles θ. Then, this relation was formulated in a mathematical form, in which the mean pressure, i.e. Hv/sinθ/2 was represented by the experimental function of tan θ/2. This is the same as the result already obtained by one of the authors in the measurement with pyramidal indenters of tungsten carbide. In the present experiment, it has been found that the value of the exponent for each specimen depends on its material ranging 0.15〜0.40 and is in a simple relation with the hardness of the test specimen. From this result, it can be expected that the maximum error in the Vickers hardness number measured will not exceed 0.2〜0.5%, if pyramidal indenters of face angles of 136°±0.5°are used. The experimental formula for the mean pressure may also be expressed by the experimental function of cosθ/2 instead of tan θ/2,in which case the value of the exponent for each specimen depends on the work-hardening characteristics of its material.
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