# Brinell Hardness Number

Written by Jerry Ratzlaff on . Posted in Classical Mechanics

Brinell Hardness Number, abbreviated as BHN or HB, is a value assigned to the hardness of metals and alloys.  To do this a steel ball is pressed into the surface of an object by a known load to deform the material.

### Brinell Hardness Number Formula

$$\large{ BHN = \frac{2\;F_a}{\pi \; D \; \left( D - \sqrt( D^2 - d^2) \right) } }$$

Where:

$$\large{ BHN }$$ = Brinell Hardness Number

$$\large{ F_a }$$ = applied load

$$\large{ d }$$ = depression diameter

$$\large{ D }$$ = steel ball diameter

$$\large{ \pi }$$ = Pi