As defined in ISO 6508 & ASTM E-18, is the most commonly used hardness test method. The Rockwell test is generally easier to perform, and quicker than other types of hardness testing methods. The Rockwell method measures the permanent depth of indentation produced by a force/load on an indenter.
The Vickers hardness test method consists of indenting the test material with a diamond indenter, in the form of a right pyramid with a square base and an angle of 136 degrees between opposite faces subjected to a load of 1g to 100 Kgf.
Brinell hardness test method is most commonly used to test materials that have a structure that is too coarse or that have a surface that is too rough to be tested using another test method, e.g., castings and forgings. Brinell testing often use a very high test load (3000 Kgf) and a 10mm ball indenter so that the resulting indentation averages out most surface and sub-surface inconsistencies.
Universal hardness testers are in fact hybrid instruments allowing the user to
make Rockwell, Vickers and Brinell hardness tests according to the applicable
ISO, ASTM and JIS standards, with one single machine.
Universal hardness testers do not convert hardness values but apply tests according to standard procedures.