Vickers Hardness Testing
Vickers hardness testing is a preferred method for assessing the hardness of all types of metals, offering the most comprehensive range of hardness scale measurements among all hardness testing techniques.
During the Vickers Hardness test, a pyramid-shaped diamond indenter is used to create a permanent indentation in the material under test by applying a specific load. This test typically utilizes lighter loads and can be used on softer materials compared to other tests.
The choice of using the Vickers Hardness test method depends on the required location, size, and shape of the hardness test. The Vickers test method is versatile in that it can be applied to a wide range of materials and properties.
Basic Procedure
To perform a Vickers Hardness test, light loads are applied to small, thin samples that require a smooth or polished surface before testing.
During the test, a pyramid-shaped diamond indenter is placed on a section of the material, and a constant load (ranging from 0.3kg to 10kg) is applied for a specified time according to international standards. The diagonal lengths of the indentation created in the material are then measured using the Vickers Hardness scale to determine the material's hardness.
Test Methods
EN ISO 6507-1 and ASTM E92 are two widely recognized standards for Vickers hardness testing, both of which use a similar test method and offer multiple test force options.
EN ISO 6507-1 specifies he following are the three ranges of test force and their corresponding Vickers hardness test designations:
F ≥ 49.03 N - Designation: HV 5 - Standard Vickers hardness test method for testing metals and materials with a medium to high hardness range.
1.961 ≤ F < 49.03 N - Designation: HV 0.2 to <HV 5 - Low-force Vickers hardness test method used to test metals and materials with a low to medium hardness range.
0.009 807 ≤ F < 1.961 N - Designation: HV 0.001 to <HV 0.2 - Vickers microhardness test method used to test the hardness of thin or small samples or surface layers of materials.
These designations indicate the appropriate Vickers hardness test method to use for a particular material depending on its hardness and the type of sample being tested.
ASTM E92 describes the Vickers hardness test and Knoop hardness test using various test forces, ranging from 9.807 × 10-3 N to 1176.80 N (1 gf to 120 kgf) and from 9.807 × 10-3 N to 19.613 N (1 gf to 2 kgf), respectively.
For testing in the microindentation force range (forces ≤ 1 kgf), additional guidance and procedures can be found in Test Method E384, which covers the microindentation hardness testing of materials.
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Both standards provide guidelines on the testing procedure, equipment requirements, and data analysis for Vickers hardness testing. These standards are widely used in industrial settings to ensure that materials meet specific hardness requirements and to facilitate comparison of hardness test results across different laboratories and testing equipment.