Hardness Testing measures a material’s strength by determining resistance to penetration. The hardness test is extremely useful in material selection because it provides a hardness value, which indicates how easily a material can be machined and how well the material will wear. It is defined as the resistance to indentation and it is determined by measuring the permanent depth of the indentation. Simply put, when using a fixed force (load) and a given indenter, the smaller the indentation, the harder the material.
We conduct hardness test by Rockwell, Brinell and Vickers Hardness Testers.
A. ROCKWELL HARDNESS TEST
This test differs from the Brinell test in the shape of the indenter and in the manner that the number is determined. The Rockwell number represents the difference in depth penetration between two loads. There are two types of Rockwell; Rockwell and Superficial Rockwell. The difference between the two is in the minor and major loads applied to the specimen. The indenter used may be a diamond cone or a hardened ball, depending principally on the characteristics of the material being tested.
B. BRINELL HARDNESS TEST
This is a simple indentation test for determining the hardness of a wide variety of materials. The test consists of applying a prescribed load, usually between 500 kg and 3000 kg, for a specified time (10-30 seconds), using a 5 or 10mm diameter tungsten carbide ball on the flat surface of a metal sample.
C. VICKERS HARDNESS TEST
This testing is similar to Brinell, in which a defined indenter is pressed into a material. Once the indenting force is removed, the resulting indentation diagonals are measured. Load capacity of Vickers Hardness Tester is 5 to 50 kg.
