When the stainless steel belt HB>450 or the specimen is too small, can not use Brinell hardness test and use Rockwell hardness measurement instead. It is a diamond cone with a top angle of 120° or a steel ball with a diameter of 1.59, 3.18mm, pressed into the surface of the tested material under a certain load, and the depth of the indentation is used to find out the hardness of the material. Depending on the hardness of the test material, it is expressed in three different scales.

HRA: is the hardness obtained by using 60kg load and diamond cone indenter, used for materials with very high hardness (such as cemented carbide, etc.).

HRB: is the hardness obtained using a 100kg load and a 1.58mm diameter hardened steel ball, and is used for materials with lower hardness (e.g. annealed steel, cast iron, etc.).

HRC: is the hardness obtained by using 150kg load and diamond cone indenter, used for materials with very high hardness (such as hardened steel, etc.)