Brinell Hardness Testing

Brinell Hardness Test 

1. Introduction to Hardness Testing 

Hardness is the ability of a material to resist indentation, scratching, or deformation. 

The Brinell Hardness Test (BHN) is one of the most widely used methods for determining the hardness of metals and alloys, particularly those with coarse structures such as cast iron and non-ferrous metals.

2. Principle of Brinell Hardness Test 

The Brinell Hardness Test is based on the principle of pressing a hardened steel or tungsten carbide ball into the surface of the test material under a fixed load for a specified time. 

The size of the indentation left on the material is measured, and the Brinell Hardness Number (BHN) is calculated using a standard formula.

3. Test Procedure 

The test is conducted as follows:

1. Preparation of the Specimen

   • The surface of the material should be clean and smooth to ensure accurate results.

   • The test piece should be thick enough to avoid distortion during testing.

2. Indentation Process

   • A hardened steel or tungsten carbide ball (usually 10 mm in diameter) is placed against the surface.

   • A fixed load (500, 1500, or 3000 kgf) is applied using a testing machine for 10 to 15 seconds.

   • After removing the load, the material retains an impression (indentation).

3. Measurement of Indentation

   • The diameter of the indentation left on the material is measured using a microscope or optical device.

   • The average diameter is taken from at least two measurements at right angles.

4. Calculation of Brinell Hardness Number (BHN)
   The BHN is determined using the formula: