How does Vickers hardness testing work?
A square-based diamond pyramid with an angle of 136° between opposite faces is pressed perpendicularly into the prepared surface under the specified test force F. After unloading, two measurable indentation diagonals d1 and d2 remain.
Vickers hardness HV is calculated from the mean diagonal d and the test force. At the same force, a smaller indentation indicates greater hardness. A marked difference between the diagonals can reveal measurement, surface or material influences.
What is the sequence of a Vickers hardness test?
Test force, dwell time, spacing, surface requirements and evaluation depend on the applicable standard and testing task.
- Define the test area, support the specimen securely and prepare a flat, clean and sufficiently smooth surface.
- Select test force and objective for the expected hardness, specimen thickness, zone and indentation size.
- Apply the diamond pyramid in a controlled manner and maintain the specified dwell time.
- Focus the indentation, measure both diagonals optically and calculate their mean.
- Report HV with test force, any required dwell-time suffix, test position and applicable standards edition.
How is a Vickers hardness value designated?
A complete designation combines the hardness value, the HV method symbol and the applied test force. A dwell time outside the standard range is added where required. Example: 610 HV 10/30.
| Element | Meaning | Example |
|---|
| 610 | measured Vickers hardness value | 610 |
| HV | Vickers method with diamond pyramid | HV |
| 10 | historical test-force designation in kgf | ≈ 98.07 N |
| /30 | dwell time where an additional statement is required | 30 s |
When is Vickers testing particularly suitable?
Vickers covers a broad hardness and force range. It is suitable for metallic materials, hardmetals and, within the applicable standard limits, metallic and other inorganic coatings. Small indentations allow measurements in phases, edge zones and prepared cross-sections.
Typical tasks include hardness traverses for case, surface or nitriding depth, weld and heat-affected zones, coatings, thin component regions and automated point grids. Very small indentations place substantially higher demands on preparation, optics and uncertainty control.
Which factors control uncertainty and comparability?
Grinding marks, curvature, blurred corners, incorrect focus, unsuitable illumination or a damaged indenter change the measured diagonals. Insufficient distance from an edge or a neighbouring indentation can also distort results through plastically affected zones.
Reliable measurements require verified force application, suitable optics, a controlled diamond indenter and routine checks with reference blocks. Automated image evaluation improves throughput but does not remove the need to review irregular indentation shapes.
Which standards define the test?
DIN EN ISO 6507-1 defines the Vickers test method for metallic materials and specified coating applications. ASTM E92 covers Vickers and Knoop testing over a broad force range; ASTM E384 provides additional requirements and guidance for microindentation testing.
- DIN EN ISO 6507-1 – Vickers hardness test, Part 1: test method
- ASTM E92 – Vickers and Knoop hardness testing of metallic materials
- ASTM E384 – microindentation hardness testing by Vickers and Knoop
Always check the edition contractually applicable to the component, product specification and test date.
