What is the Vickers Hardness Test?

The Vickers hardness test is a versatile method used to measure the hardness of materials, particularly metals. Developed in 1921 by Robert L. Smith and George E. Sandland at Vickers Ltd, it serves as an alternative to the Brinell method. The test uses a diamond indenter in the form of a right pyramid with a square base and an angle of 136 degrees between opposite faces.

Unlike other testing methods, the Vickers test is considered an "absolute" scale because the shape of the indenter is constant regardless of the magnitude of the load. This allows the same hardness scale to be used for all materials, from very soft lead to the hardest steels and ceramics.

How to Use the Vickers Hardness Calculator

To calculate the Vickers Hardness Number (HV), you need two primary measurements:

• Applied Load (F): This is the force applied to the diamond indenter, usually measured in kilogram-force (kgf). Common loads range from 1kgf to 100kgf.
• Average Diagonal Length (d): After the load is removed, a square-shaped indentation remains. You must measure the two diagonals of this square and calculate their average in millimeters (mm).

Once you enter these values into the calculator, it uses the formula: HV = 1.8544 * (F / d²) to provide the result instantly.

Frequently Asked Questions

Why is the Vickers test preferred over Rockwell?

The Vickers test is highly accurate for thin materials and small areas. Because the indenter is diamond-based, it can measure the hardest materials on earth, whereas Rockwell scales often require different indenters and loads for different hardness ranges.

What units are used in Vickers Hardness?

The resulting value is typically reported as HV (Hardness Vickers). For example, "450 HV 30" indicates a hardness of 450 measured with a 30kgf load.

The Importance of Precision

Accuracy in measuring the diagonal is critical. Since the diagonal length is squared in the denominator of the formula, a small error in measurement can lead to a significant discrepancy in the final hardness value. Digital microscopes are commonly used in laboratories to ensure the highest level of precision when reading the indentation diagonals.