The Rockwell test measures a material’s hardness by pressing a steel ball
or diamond cone (indenter) into its surface under a specific load, for a
specific time. The depth of the resulting indentation is converted into a
Rockwell hardness number (HR) on various scales, like HRB or HRC,
depending on the material type. It is a relative quick method.
The Vickers test measures material hardness by pressing a diamond-
shaped pyramid indenter into the surface under a specific load.
The diagonals of the resulting indentation are measured to calculate
the Vickers Hardness Number (VHN), making it suitable for small or
thin materials. It is widely used in research and quality control.
The Brinell hardness test measures material hardness by pressing a
hardened steel or tungsten carbide ball into the surface under a specific
load and time. The diameter of the resulting indentation is measured,
and the Brinell Hardness Number (BHN) is calculated based on the load
and indentation size. It is widely used for testing larger, coarse-grained
materials and aluminum.
The Knoop hardness test is a microhardness testing method that uses
an elongated diamond-shaped indenter to create an impression on
the material’s surface under a light load. The length of the longer diagonal
of the indentation is measured to calculate the Knoop Hardness Number
(KHN), making it ideal for very thin materials, coatings, or small areas.