In 1900, J. A. Brinell of Sweden invented ways to determine hardness by measuring the impression (or indentation) made by a steel ball forced into the metal under static loads. The definite advantage of this technique is that a single linear scale can be used to determine hardness. The standard Brinell test requires a 3000 kg load applied through a 10 mm diameter hardened steel or tungsten carbide ball. Brinell Hardness Number (BHN) is given by

2P

BHN = =-, (5.25)

pD(D — D2 — d2)

where P is the applied load in kgf and D and d are the diameters of the ball and the impression, respectively, in mm.