BHN - Brinell Hardness Number

The Brinell hardness test of  metals and alloys

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:

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