Table of Contents
What Is Vickers Hardness?
The Vickers hardness test uses a diamond pyramid indenter with a 136-degree angle between opposite faces. The test is applicable to all metals and has one of the widest scales among hardness tests. Unlike Rockwell, it uses one type of indenter for all materials, making comparisons straightforward.
The test measures both diagonals of the square indentation left by the diamond and calculates hardness from the ratio of applied force to surface area of the indentation. It is widely used in metallurgy, materials science, and quality control.
HV Formula
Where F is the force in kgf and d is the mean diagonal in mm. The constant 1.8544 comes from the geometry of the pyramid indenter (2sin(136/2)).
Hardness Comparison
| Material | Vickers HV | Rockwell HRC |
|---|---|---|
| Mild Steel | 120-180 | N/A |
| Tool Steel (hardened) | 700-900 | 60-67 |
| Aluminum 6061-T6 | 107 | N/A |
| Titanium Ti-6Al-4V | 340 | 36 |
Frequently Asked Questions
Why use Vickers over Rockwell?
Vickers uses a single indenter geometry for all materials and loads, provides better accuracy for thin materials and surface treatments (microhardness), and gives a continuous scale without the scale changes needed in Rockwell testing.
What forces are used?
Macro Vickers uses 1-100 kgf. Micro Vickers uses 10-1000 gf. The choice depends on the material thickness and the feature size being measured.
How does HV relate to tensile strength?
For steels, an approximate conversion is Tensile Strength (MPa) = HV x 3.45. This is an empirical relationship and varies by material and heat treatment.