ASTM E92 Vickers Hardness
ASTM E92 is a standardized method in the standard and low force range (200 gf - 120 kgf), used for determination of the Vickers hardness and Knoop hardness of metallic materials, where an indentation is created by means of a diamond pyramid and the size of the indentation is measured to determine the material’s hardness.
To determine Vickers hardness in the micro hardness range (1 gf - 200 gf), the ASTM E384 standard is referenced instead.
Applications Vickers hardness test procedure Vickers hardness calculation Test force application Minimum distance of test indentations Advantages and disadvantages Vickers hardness tester
Why hardness testing in accordance with ASTM E92 is important:
The ASTM E92 standard, developed by ASTM International—an organization known for their global standards—specifies a standardized method for Vickers hardness testing. This method is essential for the assessment of the wear resistance and durability of materials, which directly influences the performance and service life of the products for which they are used.
ASTM International, formally known as the American Society for Testing and Materials is a internationally recognized standards organization, which establishes technical standards for materials, products, systems and services. Vickers hardness testing to ASTM E92 is used by a variety of industries around the world.
Vickers hardness test procedure to ASTM E92
Vickers hardness testing to ASTM E92 is a hardness test method with optical evaluation in which the size of the indentation left on the surface of the test material by a pyramid-shaped diamond indenter (square base and interfacial angle of α = 136°) is measured. The test load is applied precisely and the diagonals of the indentations are used to calculate the Vickers hardness, which allows you to accurately determine the material hardness. It is important to note that the deviation of the half diagonal for Vickers must not exceed 5%.
In the Vickers hardness test according to ASTM E92, the indentations of the pyramid-shaped diamond indenter are measured under various loads, typically starting at 200 gf, depending on the material and application. The exact loads to be applied for the specific test are defined in the ASTM E92 standard to ensure reliable hardness determination.
Vickers hardness calculation according to ASTM E92
- Vickers hardness (HV) according to ASTM E92 is calculated by the ratio of the applied test force F (expressed in Newtons, N) to the area of the permanent indentation on the test material. The average of the lengths of the two diagonals d1 and d2 (measured in millimeters) is used to determine the area of this pyramid-shaped indentation. This is necessary because the base area of the Vickers indentations is often not perfectly square. The formula for the calculation can be seen below.
- The recommended hardness ranges for Vickers tests, which depend on the applied test load and the type of specimen material, are specified in the ASTM E92 standard. These hardness ranges typically vary from 1 to 3,000 HV, depending on the specific test conditions and material characteristics.
Test force application according to ASTM E92
- The force must be applied within 10 seconds without vibration or shocks.
- Then that force must be maintained for 10-15 seconds.
- Some applications may require longer exposure time, in which case the tolerances are ± 2 seconds, which must be specified in the test report.
- The implemented test loads are between 200 gf and 120 kgf.
Guidelines for test distances in Vickers hardness tests according to ASTM E92
The ASTM E92 standard also defines the minimum required distances between the test points as well as the distance to the edges of the test specimen. This serves the purpose of preventing possible distortions in the hardness measurements that could arise due to an impairment of the material structure as a result of mechanical influences.
The values of the minimum distances that must be adhered to according to ASTM E92 can be seen in the diagram.
Advantages and disadvantages of Vickers hardness testing
Advantages:
- Measures all materials, from soft to hard.
- Only one indenter is required for all tests.
Disadvantages:
- Requires a good surface finish for precise measurements.
- Slower than other methods (30-60 seconds, not including preparation).
- More costly due to optical evaluation.
Despite the necessary preparation and costs, Vickers is often the preferred method due to its versatility.
Hardness tester for standard compliant hardness testing to ASTM E92
Our modern DuraScan micro hardness tester series Vickers hardness testers can not only be used for standard-compliant hardness testing according to Vickers and Knoop, but also Brinell, and in some cases even Rockwell test tasks.
Our DuraScan Vickers hardness testers are available in various versions from simple single tests to fully automated models for complex and automated test tasks.
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Frequently asked questions about Vickers hardness testing to ASTM E92
The ASTM standard for Vickers hardness testing is ASTM E92 for the standard and low-force range of 200 gf - 120 kgf, and ASTM E384 for the micro hardness range (1 gf - 200 gf).
The ASTM standard only applies to the micro hardness range (1 gf - 200 gf), while ASTM E92 applies to the standard and low-force range (200 gf - 120 kgf).