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Engineering ToolBox > BHN - Brinell Hardness Number
The Brinell hardness test is commonly used to determine the hardness of materials like metals and alloys.
The test is achieved by applying a known load to the surface of the tested material through a hardened steel ball of known diameter. The diameter of the resulting permanent impression in the tested metal is measured and the Brinell Hardness Number is calculated as
BHN = 2 P / [π D / (D - (D2 - d2)1/2 )] (1)
where
BHN = Brinell Hardness Number
P = load on the indenting tool (kg)
D = diameter of steel ball (mm)
d = measure diameter at the rim of the impression (mm)
It is desirable that the test load are limited to a impression diameter in the range of 2.5 to 4.75 mm.
Approximate loads and Brinell Hardness Numbers:
| Brinell Hardness Number | Load (kg) |
| 160 - 600 | 3000 |
| 80 - 300 | 1500 |
| 26 - 100 | 500 |