Rockwell hardness methods are defined in ISO 6508 & ASTM E18, and are probably the most commonly used method to determine a material’s hardness since it is suitable for almost all metals and, to some extent, for plastics. Rockwell test measures the permanent depth of indentation produced by a specified force/load on a specified indenter and requires the least amount of sample preparation, making it the quickest and easiest hardness test to perform. The main advantage of Rockwell hardness testing is its speed of testing and its ability to display hardness values directly after penetrating the material.

The Rockwell hardness is determined by the application of a preliminary test force (minor load or preload), followed by an additional load (major load) to reach the total required test load, and finally returning to the same preliminary test force (minor load). The first minor load provides the zero or reference position. The major load is applied and held for a predetermined amount of time (dwell time) to allow for elastic recovery. Then the major load is removed, while still maintaining the minor load to establish the change from zero or reference position in determining a Rockwell hardness value.