Standards for hardness testing
Standards make hardness values comparable. A hardness test only yields reliable results if the test specimen, test force, test procedure, evaluation, and documentation are clearly defined. That is precisely why hardness testing standards exist. They...define how a procedure is carried out and what requirements apply to hardness testers, samples and measurement results.
the essentials in brief
- Standards define, how a hardness test is performed and evaluated.
- For Brinell, Vickers, Rockwell and Button each apply own standard series.
- A standard-compliant DIN hardness test is particularly important for Quality assurance, test reports and audits.
- The hardness value should always be specified along with the method, scale, and test conditions.
- The appropriate standard depends on the testing method, material, component and test objective .
Why standards are important in hardness testing
A hardness value is of limited value without a testing context. The numerical value itself is not the only crucial factor; the method used to determine it is equally important. Standards provide clear guidelines for this.
They define how the test is prepared, conducted, and evaluated. This allows for better comparison and documentation of measurement results, and their transparent presentation in relation to internal specifications, customer requirements, or auditing bodies. Particularly in industrial quality assurance, standards-compliant hardness testing is therefore a key component of reliable materials testing.
Overview of the most important hardness testing standards
The following standards are particularly relevant for the common hardness testing procedures:
- DIN EN ISO 6506 This regulates the Brinell hardness test. The method is primarily used for metallic materials and is described for both stationary and mobile hardness testing machines.
- DIN EN ISO 6507 This describes the Vickers hardness test. The standard is designed for metallic materials and covers different test force ranges.
- DIN EN ISO 6508 This applies to hardness testing according to Rockwell and Super-Rockwell. It describes various Rockwell scales for metallic materials and is applicable to stationary as well as portable testing machines.
- DIN EN ISO 4545 This section covers the Knoop hardness test. The method is particularly suitable for very hard, thin coatings (e.g., TiN, PVD, and CVD layers) as well as for small indentations and low test forces.
- ASTM E10, ASTM E18 and ASTM E384 These are important American standards in the field of hardness testing. They pertain to Brinell, Rockwell, and microhardness tests according to Vickers and Knoop.
What do standards regulate in hardness testing?
A standard for hardness testing not only describes the test procedure itself. It also defines the conditions under which a hardness value is valid, reproducible, and comparable.
Typical contents include:
- Type and geometry of the test specimen
- Test force and force application time
- Sample and surface requirements
- Minimum distances between test indentations and component edges
- Evaluation of the hardness value
- Information in the test report
- Requirements for testing machine, indenter and reference plates
This means the standard influences not only the measurement, but also the selection of the appropriate hardness tester and testing software.
Which standard is relevant for which testing task?
The appropriate standard is primarily determined by the chosen testing method. A different standard applies to a Brinell test than to a Vickers or Rockwell test. Additionally, the material, component geometry, test force range, and required result format all play a role.
| Test task | Relevant standard |
|---|---|
| Brinell hardness test | DIN EN ISO 6506 |
| Vickers hardness test | DIN EN ISO 6507 |
| Rockwell hardness test | DIN EN ISO 6508 |
| Knoop hardness test | DIN EN ISO 4545 |
| Brinell test according to ASTM | ASTM E10 |
| Rockwell test according to ASTM | ASTM E18 |
| Microhardness test according to ASTM | ASTM E384 |
Properly documenting results that comply with standards
A hardness value should not be stated in isolation. For a comprehensible evaluation, the test method, the scale, the test force, and other relevant test conditions must be included in the result. Depending on the method, additional information may be required, for example, regarding the exposure time or the type of test specimen.
Complete documentation is particularly important when results are used for test reports, supplier verifications, complaints, or audits. It makes it clear under what conditions the hardness test was carried out.
Common mistakes when dealing with standards
Mistakes often do not arise from the Hardness Tester The error is not caused by the individual, but by an unsuitable application of the standard. Typical causes include incorrect procedure selection, an unsuitable sample surface, or incomplete reporting of results.
Conversions between different hardness scales should also be critically examined. Hardness values from different methods are not automatically directly comparable. A conversion is only meaningful if the material, test conditions, and underlying standard permit it.
Advice on standard-compliant hardness testing
A standard-compliant hardness test begins with the selection of the appropriate method. Subsequently, the hardness tester, test specimen, force range, specimen holder, software, and documentation must conform to the relevant standard.
SCHÜTZ+LICHT provides support in the selection of suitable hardness testers and in the practical implementation of standard-compliant testing procedures.
Frequently asked questions about DIN standards for hardness testing
Which standard applies to the hardness test?
That depends on the testing method. For Brinell, DIN EN ISO 6506 is relevant, for Vickers DIN EN ISO 6507, for Knoop DIN EN ISO 4545, and for Rockwell DIN EN ISO 6508.
Why are standards important in hardness testing?
Standards define testing conditions, evaluation, and documentation. This makes hardness values traceable, comparable, and verifiable.
What does DIN EN ISO hardness testing mean?
A DIN hardness test refers to a hardness test performed according to a DIN standard valid in Germany. These are generally the national derivations of the EN or ISO standards that describe internationally harmonized testing procedures.
DIN = German Institute for Standardization
EN = European Standard
ISO = International Organization for Standardization
What information is required for a standard-compliant hardness value?
Depending on the method, this includes the hardness value, the scale (abbreviation), the test specimen, and the test force. 3 typical examples:
60HRC Hardness value HärteRRockwellC - the identification letter C simultaneously defines the type of intruder (Conus) and the test forces
250HBW2,5/187,5 Hardness value HärteBrinellWolframcaribide(-sphere), Ball diameter, Inspector (kgf)
700HV1 Hardness value HärteVickers, test force (kgf)
Which standard applies to the testing of hardness testing equipment?
The requirements for the calibration of hardness testing machines are regulated in the respective standard series, Part 2:
Brinell: ISO 6506-2 / ASTM E10
Vickers: ISO 6507-2 / ASTM E384
Knoop: ISO 4545-2 / ASTM E384
Rockwell: ISO 6508-2 / ASTM E18
