BAQ alphaDUR mini Manual page 32

THE UCI METHOD
The advantages of the UCI method are the ease of automation and the very
good reproducibility of the hardness readings. The reproducibility of the
measurements is better than with optical methods of hardness testing because
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the total area of contact (proportional to d ) enters into the measurement and
not only the diagonal d or a diameter. Moreover the measurement results are
independent from the subjective view of a single examiner and the test is very
fast executable.
For carbon steel and low alloyed steel, hardness reference samples are used
for purpose of calibration. The low variation of the elastic modulus of this group
of materials can be neglected.
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