Depending on the field of application, different main loads (test loads) are used during hardness testing. Depending on the level of the main load applied to a test workpiece during the hardness test, a distinction is made between micro, small load and macro hardness testing in the ISO standard.
In the macro range (conventional hardness range), large test loads ≥ 5 kgf are used which result in correspondingly large hardness impressions in the test workpieces. The macro hardness testing methods include Brinell, Vickers and Rockwell.
A hardness test in the low-load range is one in which the test load lies between 0.2 kgf and 5 kgf (test load ≥ 0.2 kgf and < 5 kgf). The most common low-load testing method is Vickers. Low-load hardness testing is used predominantly for testing small parts, thick coatings and materials with a low hardness. < 5 kgf).
During micro hardness testing, low test loads < 0.2 kgf are used, which only leave very small indents in the test pieces (most common method: Vickers). Micro hardness testing can therefore be used to test the hardness of thin layers or, e.g., the hardness of individual crystallites or inclusions.