Brinell Hardness Number Test Calculator

What is the Brinell Hardness Number (BHN)?

The Brinell Hardness Number (BHN) is a measure of the hardness of a material, determined by forcing a hard steel or carbide sphere of a specified diameter under a specified load into the surface of a material and measuring the diameter of the indentation left after the test.

Formula

The formula for the Brinell Hardness Number is:

\[ BHN = \frac{2F}{\pi D(D - \sqrt{D^2 - d^2})} \]

Where:

• \( F \) is the applied load (in kgf)
• \( D \) is the diameter of the indenter (in mm)
• \( d \) is the diameter of the indentation (in mm)

Calculation Steps

To calculate the Brinell Hardness Number:

1. Measure the diameter of the indentation (d) after applying the load
2. Calculate \( D^2 \) and \( d^2 \)
3. Calculate \( D^2 - d^2 \)
4. Calculate \( \sqrt{D^2 - d^2} \)
5. Calculate \( D - \sqrt{D^2 - d^2} \)
6. Multiply the result by \( \pi D \)
7. Divide \( 2F \) by the result from step 6

Example and Visual Representation

Let's visualize the Brinell hardness test:

This diagram illustrates:

• The spherical indenter (blue circle)
• The material surface (green curve)
• The indentation diameter (red line)
• The applied load (F)
• The ball diameter (D)
• The indentation diameter (d)