GB/T 4340.1-2009 English Translation: Metallic Materials Vickers Hardness Test Method
GB/T 4340.1-2009 is the Chinese national standard for the Vickers hardness test method for metallic materials. This English translation is prepared as a practical reference for material inspection, heat-treatment verification, flange material quality control, and laboratory reporting.
Standard Information
- Standard number: GB/T 4340.1-2009
- English title: Metallic materials – Vickers hardness test – Part 1: Test method
- Chinese title: 金属材料 维氏硬度试验 第1部分：试验方法
- Adoption relationship: ISO 6507-1:2005, modified
- Replaces: GB/T 4340.1-1999
- Issued: June 25, 2009
- Implemented: April 1, 2010
- ICS: 77.040.10
- CCS: H 22
1. Scope
This part of GB/T 4340 specifies the principle, symbols and designations, testing apparatus, test piece requirements, test procedure, uncertainty of results, and test report requirements for the Vickers hardness test of metallic materials.
The method covers three ranges of test force for metals. It is applicable to indentation diagonal lengths from 0.020 mm to 1.400 mm. When the indentation diagonal is less than 0.020 mm, the increase in measurement uncertainty must be considered. The Vickers test requirements for specific materials or products should be defined in the relevant product standards.
2. Test Force Ranges
| Range | Test force F | Typical designation |
|---|---|---|
| Vickers hardness test | F >= 49.03 N | HV5 and above |
| Low-force Vickers hardness test | 1.961 N <= F < 49.03 N | HV0.2 to below HV5 |
| Vickers microhardness test | 0.09807 N <= F < 1.961 N | HV0.01 to below HV0.2 |
3. Normative References
- GB/T 4340.2, Metallic materials – Vickers hardness test – Part 2: Verification and calibration of testing machines.
- GB/T 4340.3, Metallic materials – Vickers hardness test – Part 3: Calibration of reference blocks.
- GB/T 4340.4, Metallic materials – Vickers hardness test – Part 4: Tables of hardness values.
- JJF 1059, Evaluation and expression of uncertainty in measurement.
4. Principle
A diamond indenter in the form of a right pyramid with a square base and a specified angle between opposite faces is pressed into the surface of a test piece under a selected test force. After the force is maintained for the specified duration and then removed, the two diagonal lengths of the indentation are measured on the test surface.
The Vickers hardness value is proportional to the test force divided by the surface area of the indentation. The indentation is regarded as an ideal square-based pyramid with the same angle as the indenter.
5. Symbols and Calculation
| Symbol | Description |
|---|---|
| F | Test force, in newtons (N) |
| d1, d2 | The two measured diagonals of the indentation, in millimetres (mm) |
| d | Arithmetic mean of d1 and d2, in millimetres (mm) |
| HV | Vickers hardness value |
The hardness value is calculated from the mean indentation diagonal:
HV = 0.1891 x F / d²
where F is in newtons and d is in millimetres. The hardness value may also be obtained from the hardness value tables in GB/T 4340.4.
6. Designation of Vickers Hardness
The Vickers hardness result is expressed by the hardness value, followed by the symbol HV, followed by the test force designation. If the duration of the test force is outside the normal range, the duration is also stated.
- Example: 640 HV 30 means a Vickers hardness value of 640 measured with a test force of 294.2 N, corresponding to HV30.
- Example: 640 HV 30/20 means the same test force with a force application duration of 20 s.
7. Testing Apparatus
- The testing machine shall meet the requirements of GB/T 4340.2.
- The diamond indenter shall have a square pyramidal shape with the specified included angle between opposite faces.
- The measuring device shall be capable of measuring the two indentation diagonals with adequate resolution and accuracy for the selected force range.
- Before routine testing, the user should check the testing machine with reference blocks calibrated according to GB/T 4340.3.
8. Test Piece
The test surface shall be smooth, flat, clean, and free from oxide scale, foreign matter, lubricant, or other conditions that may affect indentation measurement. Surface preparation must not introduce excessive heating, cold working, or other changes that could alter the hardness of the material.
The thickness of the test piece, or of the tested layer, shall be sufficient so that no visible deformation appears on the opposite surface after the test. In general, the thickness should be at least 1.5 times the diagonal length of the indentation unless a product standard specifies otherwise.
9. Test Procedure
- Carry out the test at a temperature between 10 °C and 35 °C unless otherwise specified. For controlled conditions, a temperature of 23 °C +/- 5 °C may be used.
- Select a suitable test force according to the material, expected hardness, and product standard.
- Place the test piece on a rigid support so that it cannot move during loading.
- Bring the indenter into contact with the test surface and apply the test force smoothly without shock or vibration.
- Maintain the full test force for 10 s to 15 s unless otherwise specified. For special materials, a different duration may be specified and shall be reported.
- After unloading, measure the two diagonals of the indentation and use their arithmetic mean for hardness calculation.
10. Spacing of Indentations
The indentation shall be placed far enough from any edge or adjacent indentation to avoid mutual influence.
- For steel, copper, and copper alloys, the distance from the centre of an indentation to the edge should be at least 2.5 times the mean diagonal, and the distance between centres of adjacent indentations should be at least 3 times the mean diagonal.
- For light metals, lead, tin, and their alloys, the distance from the centre of an indentation to the edge should be at least 3 times the mean diagonal, and the distance between centres of adjacent indentations should be at least 6 times the mean diagonal.
11. Measurement of the Indentation
The two diagonals of the indentation shall be measured. For flat surfaces, the difference between the two diagonal lengths should not exceed 5% of the mean diagonal length. If the difference exceeds this value, the condition shall be stated in the test report.
The optical magnification should be selected so that the indentation diagonal occupies approximately 25% to 75% of the field of view, helping the operator measure the indentation reliably.
12. Uncertainty of Results
When required, measurement uncertainty shall be evaluated according to JJF 1059. For Vickers hardness testing, uncertainty may be evaluated from all relevant components involved in direct calibration, or by indirect calibration using a certified hardness reference block. Guidance for uncertainty evaluation is provided in the informative annex of the standard.
13. Test Report
The test report shall include at least the following information:
- A reference to GB/T 4340.1-2009.
- Identification and description of the test piece.
- The test result and the Vickers designation used.
- The selected test force and the duration of force application when it is not the standard duration.
- Any operation not specified in the standard.
- Any condition or detail that may affect the test result.
- The test temperature if it is outside the specified range.
14. Practical Notes for Material Inspection
A strict comparison of Vickers hardness values is meaningful only when the same test force is used. Conversion from Vickers hardness to other hardness scales or to tensile strength should be avoided unless a reliable conversion basis has been established by comparison testing for the relevant material.
For flange materials, forgings, heat-treated steel parts, and weld inspection, the test location, surface preparation, force level, indentation spacing, and reporting format should be agreed before testing to avoid inconsistent acceptance decisions.
Original Chinese PDF
The original Chinese PDF is embedded below for reference. The embedded PDF remains in Chinese and has not been translated or modified.