What does the Brinell Hardness Number represent?

The Brinell Hardness Number (BHN) specifically represents the diameter of the indentation made by a hard metal ball when a specified force is applied to it on the material being tested. This indentation is measured after the test is conducted, and its diameter is directly used to calculate the hardness value of the material. The larger the indentation, the softer the material, which correlates to a lower hardness number.

The Brinell test involves applying a specific load for a predetermined amount of time, after which the diameter of the resulting indentation is measured. This measurement, along with the applied load, allows for the calculation of the BHN using the formula that incorporates both the force and the area of the indentation.

While the force applied during the test, depth of the indentation, and type of indenter used are all important in the broader context of material testing, they do not define the value of the Brinell Hardness Number, which is focused specifically on the diameter of the indentation itself.