2: Brinell, Vicker's & Rockwell Tests
The Brinell test uses a hardened steel ball indentor with a diameter of 10mm. The indentor is applied to the test material under a load of 3000kg. The surface area of the indentation is then measured to derive the hardness, HB, of the material.
Brinell testing is not suitable for very hard materials since the hardness of the test material approaches that of the steel indentor. As a result there will be a tendency for the indentor to deform.
Vicker's Diamond Test
The Vicker’s Diamond test utilises a pyramidal shaped diamond indentor with an apex angle of 120°.
The use of diamond as an indentor means that very hard materials can be tested as they are not likely to deform the indentor.
The force, F, is taken and the diagonals of the impression are measured. The mean of these two values, D, is used to determine the hardness, HV, of the material.
The Rockwell test is designed as a method of hardness testing for rapid comparative analysis.
The depth of the impressions are measured and are rated on a dial calibrated, inversely, into 100 divisions. A deep impression will result in a low value, which implies a soft material.
Hardened steel ball indentors are used with diameters of 1/16 inch, 1/8 inch, 1/4 inch, and 1/2 inch. Standard indenting loads are 60kg, 100kg and 150kg.