ASTM E92 is the standard test method published by ASTM International that specifies how Vickers hardness and Knoop hardness of metallic materials are determined using diamond indenters and test forces in the macro range (typically 1 kgf to 120 kgf for Vickers). It defines the indenter geometry, force application, indent measurement, verification of machines, and reporting requirements that laboratories, educational institutions, and manufacturers reference in tenders and quality plans worldwide.
What ASTM E92 covers
ASTM E92 (current designation “Standard Test Methods for Vickers Hardness and Knoop Hardness of Metallic Materials”) describes two closely related indentation hardness methods. In the Vickers method a square-based pyramidal diamond indenter with an angle of 136 degrees between opposite faces is pressed into the surface of the test piece under a specified force for a defined dwell time. After removing the force, the two diagonals (d1 and d2) of the residual indent are measured optically and averaged.
The Vickers hardness number is calculated as:
HV = 1.8544 × F / d²
where F is the applied force in kilogram-force (kgf) and d is the mean diagonal length in millimetres, giving HV in kgf/mm². When F is expressed in newtons the constant becomes 0.1891 and the result is reported in the same HV units by convention. The Knoop method uses an elongated rhombic-based pyramidal diamond and reports HK from the long diagonal, and is particularly useful for thin coatings, brittle materials, and narrow features.
The standard applies to metallic materials across a wide hardness range and specifies requirements for the testing machine, the indenter, the measuring system, direct and indirect verification using certified reference blocks, spacing between indents, minimum specimen thickness, and surface preparation. Test force selection, dwell time (commonly 10 to 15 seconds unless otherwise specified), and reporting format (for example 640 HV 30 for a 30 kgf test) are all defined so that results are reproducible between laboratories.
Why it matters for procurement
Tender documents for teaching laboratories, materials testing labs, quality-control departments, and engineering colleges routinely require Vickers hardness testers to be “compliant with ASTM E92 and/or ISO 6507” and to be supplied with traceable calibration certificates against certified reference test blocks. Citing the correct standard prevents disputes at inspection, ensures the machine’s force range, optical resolution, and diagonal measuring accuracy match the intended application, and allows buyers to compare equipment on a like-for-like basis.
ASTM E92 is frequently cross-referenced with ASTM E384 (which covers the micro-indentation range using forces of 1 gf to 1 kgf) and with the ISO 6507 series used across Europe and increasingly in India. Understanding the equivalents makes it easier to align a purchase order with existing quality-management-system documentation.
Equivalent international standards
| Region / body | Standard | Scope |
|---|---|---|
| ASTM International (USA) | ASTM E92 | Vickers and Knoop hardness of metals, macro range |
| ASTM International (USA) | ASTM E384 | Micro-indentation hardness (Vickers and Knoop, low forces) |
| ISO (international) | ISO 6507-1 to -4 | Vickers hardness test: method, verification, calibration of reference blocks |
| ISO (international) | ISO 4545-1 to -4 | Knoop hardness test |
| BIS (India) | IS 1501 (Part 1) | Vickers hardness of metallic materials, aligned with ISO 6507-1 |
| EN (Europe) | EN ISO 6507-1 | European adoption of ISO 6507-1 |
| JIS (Japan) | JIS Z 2244 | Vickers hardness test for metallic materials |
Testing procedure summary
- Specimen preparation. The test surface is ground and polished so that the indent edges can be resolved clearly under the measuring microscope. Minimum thickness is at least 1.5 times the diagonal length of the expected indent to avoid anvil effect.
- Machine setup. Select the test force appropriate to the material and geometry (for example HV 10 for general steels, HV 1 for thin sections). Verify that the machine has current direct or indirect verification per ASTM E92 using certified reference blocks in the same hardness range.
- Indent application. Bring the 136-degree diamond pyramid into contact with the surface, apply the force smoothly without impact within the specified time, hold for the dwell period (typically 10 to 15 seconds), and remove the force.
- Diagonal measurement. Using the machine’s optical or digital measuring system, measure both diagonals d1 and d2 of the residual indent. Their arithmetic mean d is used in the HV calculation.
- Calculation and spacing checks. Compute HV = 1.8544 F / d². Confirm that the distance between the centre of the indent and the specimen edge, and between adjacent indents, meets the minimum spacing rules in ASTM E92 to avoid interference.
- Reporting. Report the result in the format hardness value, HV symbol, test force in kgf, and dwell time if non-standard (for example “285 HV 10” or “285 HV 10/20” for a 20-second dwell), together with the reference to ASTM E92.
Scientico compliance
Scientico India manufactures Vickers and combined hardness testers configured to operate within the parameters described by ASTM E92 and the equivalent ISO 6507 series. Machines are supplied with 136-degree diamond Vickers indenters, selectable test forces across the standard range, calibrated optical or digital diagonal measuring systems, and traceable calibration documentation against certified reference test blocks so that laboratories can perform the direct and indirect verifications the standard requires. Configuration, force range and measuring resolution are confirmed against the buyer’s tender specification before dispatch.
Related Scientico equipment
- Vickers hardness testing machines (macro range, bench models)
- Combined Rockwell / Brinell / Vickers universal hardness testers
- Micro-Vickers hardness testers for thin sections and coatings
- Certified Vickers reference test blocks for indirect verification
- Diamond Vickers indenters (136-degree) and Knoop indenters
- Metallurgical microscopes and specimen preparation equipment for polishing test surfaces
Related pages: see our Quality & Certifications page for ISO 9001:2015 and CE documentation, or head to Contact Us for a CIF quotation and tender-ready specification sheet.
Frequently Asked Questions
What does ASTM E92 specify?
ASTM E92 specifies the Vickers and Knoop hardness test methods for metallic materials, including indenter geometry, test forces, dwell time, diagonal measurement, machine verification, and reporting format so results are reproducible between labs.
What is the Vickers hardness formula in ASTM E92?
HV = 1.8544 x F / d^2, where F is the applied force in kgf and d is the mean of the two indent diagonals in mm. HV is expressed in kgf/mm^2 and reported with the test force, e.g. 285 HV 10.
What is the angle of the Vickers indenter?
The Vickers indenter is a square-based pyramidal diamond with an included angle of 136 degrees between opposite faces, as defined in ASTM E92 and the equivalent ISO 6507-1.
Is ASTM E92 the same as ISO 6507?
They are closely aligned but not identical. ISO 6507-1 is the international Vickers standard used across Europe (as EN ISO 6507-1) and adopted in India as IS 1501 Part 1. Many tenders accept either standard; check the wording.
When should I use ASTM E384 instead of E92?
Use ASTM E384 for micro-indentation hardness testing with forces from 1 gf up to 1 kgf, typically for coatings, case-hardened layers, and small features. ASTM E92 covers the macro range up to about 120 kgf.
Do Scientico hardness testers include calibration for ASTM E92?
Scientico supplies Vickers and combined hardness testers with traceable calibration against certified reference test blocks so buyers can carry out the indirect verification ASTM E92 requires. Request the certificate list with your quote.
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