Vickers hardness test

The Vickers method is a static hardness testing method, which can be further characterised as follows:
 

• It is one of the standardised procedures (ISO 6507, ASTM E92, ASTM E384).
• The Vickers method has a test load range from 1 gf according to ISO respectively from 1 gf up to 120 kgf according to ASTM, which means that this method can be used for hardness testing across all load ranges (from the micro to the low-load through to the macro range).
• It is an optical method. This means that the size of indentation left by the indenter is measured to determine the hardness value of a test specimen.
• Indenter shape and material: The indenter is an equilateral pyramid (with a square base) made of diamond with a plane angle of 136°.

When using the Vickers hardness testing method, it is usually necessary to prepare the surface of the specimen to be tested, as the specimen surface quality requirements are significantly stricter than those for the Rockwell method, in which it is sufficient for the surface to be free of impurities.

In detail, the specimen to be measured should meet the following requirements for the Vickers method:

• The specimen should be polished (micro hardness testing) or precision-ground (macro hardness testing).
• The specimen should preferably be clamped strongly, so that it cannot move during the testing process (practical tip: measure with nose cone resp. with suitable test anvil, fix embedded specimen in a specimen holder).

In addition, to avoid affecting the test result, care must be taken to ensure that the test is not disturbed by any shock or vibration (an anti-vibration table, etc., may be required).

A Vickers hardness value consists of the following components:

1. The numeric hardness value (between 1 and 3000);
2. The two letters "HV", standing for "Hardness according to Vickers";
3. The applied test load in kgf;
4. According to ISO 6507: The dwell time of the test load, but only if this is not between 10 and 15 seconds (uncommon in practice)

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