How to Test the Brinell hardness of Materials?

Hardness tests on materials consist of pressing a hardened ball point into a specimen and measuring the size of the resulting indentation (see Figure). The method shown is the Brinell method, which utilizes a ball. The ball size is 10 mm for most cases or 1 mm for light work.

Let:

D = diameter of indentation (mm)

Db = diameter of baIl (mm)

F = force on ball (kgf)

Values of F:

Steel F =3 x ODb ^2

Copper F = 10 x Db^2

Aluminum F = 5 x Db^2