Everyone knows which objects are hard and which are not.
It is simply something that people know but doesn’t give much thought to.
So, if any of these people are asked how they have come to such a deduction, they may just have to think for a while.
Hardness, for those wondering, refers to the varying ability of a given object or material to resist indentation when a force is applied to it.
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.
Among hardness tests that are standardized, 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.
Cast iron is one material that requires the Brinell Test as it calls for a relatively large indenter (like those used in Brinell Tests e.g.carbide ball).
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.
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.