Hardness tests are a measure of resistance to indentation and are notable for being fast, easy and non-destructive. A force is applied to an indenter, such as a steel ball or a diamond pyramid, and the resulting size or depth of the indentation in the surface of the material is measured using a microscope.
The size and material of the indenter and the scale of the applied load will depend on the type of hardness test. Some of the more common tests are Brinell and Rockwell to measure macrohardness, Knoop to measure microhardness, and Vickers to measure both macro- and microhardness. Nanoindentation can also be done with the Berkovich test.
Specific hardness formulas are matched to each type of hardness test. A lower number indicates that the material is easily scratched or dented, while a higher number indicates greater resistance to indentation. Hardness is often related to other properties, such as tensile strength. For steels, cast iron and brass, there is a linear relationship between hardness and tensile strength.
Tinius Olsen offers force measurement equipment and material testing machines for hardness testing. All testing hardware is fully complemented by our Horizon software.