The definition of hardness testing is “A test to determine the resistance a material exhibits to permanent deformation by penetration of another harder material”. However, hardness is not a fundamental property of a material. Therefore, when drawing conclusions of a hardness test, you should always evaluate the quantitative value in relation to:
The given load on the intender.
A specific loading time profile and a specific load duration.
A specific indenter geometry
A hardness test is typically performed by pressing a specifically dimensioned and loaded object (indenter) into the surface of the material you are testing. The hardness is determined by measuring the depth of indenter penetration or by measuring the size of the impression left by an indenter.
Things to consider while selecting a hardness test method:
- The type of material to be hardness tested.
- Whether compliance with a standard is required.
- The approximate hardness of the material.
- The homogeneity/heterogeneity of the material.
- The size of the part.
- Whether mounting is necessary.
- The number of samples to be tested.
- The required accuracy of the result.