Vickers Hardness Calculator

The Vickers test presses a geometrically precise diamond pyramid into the material surface under a controlled force for a specified dwell time (typically 10–15 seconds). After the load is removed, the two diagonals $$d_1$$ and $$d_2$$ of the square impression are measured using a microscope, and their mean is computed:

$$d = \frac{d_1 + d_2}{2}$$

The Vickers hardness is then:

$$HV = \frac{2F \sin(\alpha/2)}{d^2} = \frac{1.8544 \, F}{d^2}$$

where $$\alpha = 136°$$ is the included angle between opposite faces of the diamond pyramid. This angle was chosen so that the depth-to-diagonal ratio is approximately 1:7, producing a well-defined indent even in hard materials.

The result is reported as the hardness number followed by HV and the test force, e.g., "640 HV30" means 640 Vickers hardness at 30 kgf force. Key advantages of the Vickers method include:

• Scale independence: Unlike Rockwell, a single formula covers all materials.
• Geometric similarity: The indent shape is the same regardless of load, so results are (theoretically) force-independent.
• Precision: Microscopic diagonal measurement allows testing of thin coatings, individual grains, and weld zones.

Potential error sources include: diagonal measurement uncertainty (especially at low loads where indents are small), surface preparation quality, vibration during testing, and the indentation size effect (ISE) at micro-hardness levels where apparent hardness increases at lower loads.

The Vickers hardness number directly indicates resistance to plastic deformation by indentation. Common ranges: pure aluminum 15–30 HV, mild steel 120–180 HV, quenched and tempered steel 300–700 HV, tungsten carbide 1500–2200 HV, and diamond ~10000 HV. When comparing values, ensure the test force is the same, as the indentation size effect can cause slight variations at different loads. If the two diagonals differ significantly (d₁ ≠ d₂), this may indicate material anisotropy, surface tilt, or indenter misalignment.