Brinell hardness test

It determines hardness through the scale of penetration of an indenter, loaded on a material test-piece.

However, it also had the useful feature that the hardness value divided by two gave the approximate UTS in ksi for steels.

The typical test uses a 10 mm (0.39 in) diameter steel ball as an indenter with a 3,000 kgf (29.42 kN; 6,614 lbf) force.

The Brinell hardness number can be correlated with the ultimate tensile strength (UTS), although the relationship is dependent on the material, and therefore determined empirically.

In former standards HB or HBS were used to refer to measurements made with steel indenters.