Vickers Hardness Testing

3. Test Procedure

Step 1: Sample Preparation

• The material surface should be polished and free from rust or dirt.

• The test specimen should be flat and smooth for accurate measurements.

Step 2: Applying the Load

• A diamond pyramid indenter is placed on the material.

• A specific load (1 gf – 100 kgf) is applied using a Vickers hardness testing machine.

• The load is held for 10 to 15 seconds.

Step 3: Measuring the Indentation

• After the load is removed, the indentation is measured under a microscope.

• The diagonal lengths (d1 and d2) of the indentation are recorded.

• The average diagonal length ddd is calculated as:

d= (d1​+d2)/2​​

Step 4: Calculating Hardness Value

• Using the Vickers formula, the VHN (or HV) is calculated.

4. Advantages of Vickers Hardness Test

✔ Suitable for very thin materials (e.g., foils, coatings).
✔ Accurate and repeatable results due to small indentation.
✔ Can test very hard materials (e.g., hardened steel, ceramics).
✔ Same indenter can be used for all loads, unlike Rockwell.

5. Limitations of Vickers Hardness Test

❌ More time-consuming compared to Rockwell or Brinell tests.
❌ Requires a microscope for indentation measurement.
❌ Not ideal for large parts, as small indentations may not represent bulk properties.

6. Applications of Vickers Hardness Test

• Microhardness testing of thin coatings and films.

• Aerospace and automotive industries for testing high-strength materials.

• Metallurgical research for studying phase changes in metals.

• Quality control in precision manufacturing.

7. Comparison: Vickers vs. Brinell vs. Rockwell