The ability of any certain object or substance to resist indentation when a force is applied to it is known as hardness. An object’s hardness should be classified as a feature or a characteristic rather than one of its properties and the hardness is generally measured by calculating the permanent area of the indentation caused by a fixed load.
The Hardwell and Brinell tests are two specific methods to measure hardness.
The Rockwell Test is the easier of the two methods and tends to be more accurate. It can be utilized for testing metals of all sorts including hard metals (unlike Brinell Tests), except for circumstances where external factors play a part in preventing it.
It also happens to be the most commonly used test.
The Rockwell Test uses specific steps to measure hardness. Unlike the Brinell Test, it uses a smaller indenter such as a diamond. This indenter is used to apply a minor load (Increased load/force is applied later) so as to avoid breaking the surface of the material. This way it proves to be a less destructive method in comparison to the Brinell Test.
The Vickers test is ideal for test materials that do not require much load/force but rather increased accuracy during the testing procedure. Equipped with the sharp point of its diamond indenter, the Vickers test also makes use of an optical system that enables magnification of the material’s target area.
This magnification ability allows the tester to focus on microelements on the surface and thus, be more accurate. This is vastly different from the other tests.
However, compared to the Brinell and Rockwell Tests, the Vickers Test is more expensive due to the preparation required and the cost of obtaining the optical system. The testing procedure also takes more time than the Rockwell Test.
The Brinell Hardness Test method happens to be the very first test that was used widely. It is usually used to measure the hardness of metallic materials with a specific preference given to materials that are rough.
It also may be the case that the material is simply unsuitable to go through other tests, thus leaving the Brinell test as the sole method of determining hardness.
The Brinell test, however, is not suitable for materials that have hardened too much with hardened steel being one of the obvious examples.
In addition to that, this method also happens to be quite slow in comparison to other tests and tends to make irreparable imprints on the metallic object or material.