Rockwell test was developed by the Wilson instrument co U.S.A in 1920. This test is an indentation test used for smaller specimens and harder materials. The test is subject of IS: 1586. The hardness of a material is resistance to penetration under a localized pressure or resistance to abrasion. Hardness tests provide an accurate, rapid and economical way of determining the resistance of materials to deformation. There are three general types of hardness measurements depending upon the manner in which the test is conducted:

1. Scratch hardness measurement : The materials are rated on their ability to scratch one another and it is usually used by mineralogists only.
2. Rebound hardness measurement : A standard body is usually dropped on to the material surface and the hardness is measured in terms of the height of its rebound.
3. Indentation hardness measurement : The general means of judging the hardness is measuring the resistance of a material to indentation.