The hardness test methods to Rockwell are simple and require very little time to prepare the specimen and run the test.
The indenter indents the specimen to a depth of t0 under test preload F0. This indentation depth defines the reference level for further measurement. After the depth measurement has been zeroed, the test load Fm is applied and kept constant over the duration of the load application. The indenter then reaches the indentation depth t1.
Following the load application period, the load is removed back down to the test preload F0. The indenter moves by the elastic portion of the indentation depth, back to the remaining indentation depth h. The Rockwell hardness is then determined according to the various scales.
Possibility of error during test sequence due to permanent displacement of specimen and other components in force flow.
- Limited capability for testing case-hardened specimens due to high test loads involved.
- Diamond indenter sensitive to damage, with consequent risk of measuring errors.
- Poor hardness differentiation.
- Influence of indenter on test result when using conical indenters.