Brinell Hardness the hardness value shall be calculated from the following formula applying the test load to leave a spherical indentation in the test surface with a steel or tungsten carbide alloy ball indenter and the indented spherical area obtained by the diameter of indentation.
HBS : Brinell Hardness measured with a steel ball indenter
HBW : Brinell hardness measured with a tungsten carbide alloy ball indenter
F : Test load (N) (1)
S : Surface area of indentation (mm2)
D : Diameter of the ball indenter (mm)
d : Diameter of indentation
Provided that the the numerical value of HBS (or HBW) shall not be affixed with the unit.
Note : (1) When the unit of test load F is expressed in kgf, Brinell hardness shall be
calculated from the following formula :