This standard is applicable to the determination of Vickers hardness of cemented carbide. GB/T 7997-1987 Test method for Vickers hardness of cemented carbide GB/T7997-1987 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Test method for Vickers hardness of cemented carbide
Hardmetals- Vickers hardness testThis standard is applicable to the determination of Vickers hardness of cemented carbide. This standard is equivalent to the international standard ISO3878--1983 "Test method for Vickers hardness of cemented carbide". Symbols and explanations
1.1 The symbols and explanations used in this standard are shown in the table below. Symbol
The angle between the two opposite surfaces at the top of the indenter
Test force, N (kgf)
The arithmetic mean of the two diagonals d. and d. of the indentation, mm2F · sin136°
Vickers hardness = 0.102×
0. 1891 ×-
2 sin 136°
=1.8544×
Vickers hardness one
UDC 669.15.018.25
:620.178.1
GB 7 9 9 7 -- 8 7
, if the unit of the test force is expressed in kgf, 1.2 Vickers hardness is expressed by the symbol HV, the hardness value is before HV, and the test force is after HV. For example:
1500HV294.2 means that the Vickers hardness value measured with a test force of 294.2N (30kgf) is 1500. 2 Principle of the method
A regular tetrahedral diamond indenter with an angle of 136\ between the opposite faces is pressed into the sample surface with a selected test force. After maintaining the test force for a specified time, the test force is removed and the length of the two diagonal lines of the indentation is measured. See Figures 1 and 2. Approved by China National Nonferrous Metals Industry Corporation on January 27, 1987 526
Implementation on March 1, 1988
GB 7997—87
The Vickers hardness value is the quotient obtained by dividing the test force by the surface area of ​​the indentation. The calculation formula is shown in the previous table. 3 Test Instruments
3.1 Vickers Hardness Tester
The Vickers hardness tester shall have various test forces ranging from 9.807N to 490.3N (1~~50kgf). The test force tolerance shall not exceed ±1%, and the variation shall not exceed 1%.
3.2 Indenter
The angle between the opposite faces of the diamond cone is 136±0.5°, the deflection between the cone axis and the indenter handle axis shall not exceed 0.5%, and the length of the intersection line (cross edge) of the two opposite faces of the cone shall not exceed 0.002mm. See Figure 3. The maximum value is \.02mm
3.3 Measuring device
The measuring device can measure the diagonal of the indentation with the following accuracy: d ≤100μm: ±0. 2um
100umd200um: ±1.um
t ≥200μum: ±0.5%
3.4 ​​Calibration of Vickers hardness tester
The Vickers hardness tester should be calibrated regularly by the metrology department. 4 Sample
GB799787
4.1 The thickness of the sample surface should be above 0.2mm. The sample surface should be prepared according to the sample preparation method of GB3489-83 "Hard alloy-metallographic determination of porosity and uncombined carbon". In the process of sample preparation, the influence of heat, cold working, etc. on the surface hardness of the sample should be avoided as much as possible. When the test surface is a curved surface, the curved surface of the sample should be processed into a flat surface before testing. 4.2 The thickness of the prepared specimen shall not be less than 1 mm. The specimen shall be of sufficient thickness so that it will not break or deform when tested under the selected test force. For specimens with small cross-sections or irregular shapes, some form of additional support must be taken, such as embedding in plastic material. 5 Test
5.1 The test force is in the range of 9.807N (1kgf) to 490.3N (50kgf). The recommended test force is 294.2N (30kgf). 5.2 The specimen shall be firmly placed on a rigid support table so that it does not move during the test. The surface contacted by the test should be clean and free of foreign matter.
5.3 Without impact or vibration, press the indenter vertically into the tested surface of the specimen until the applied test force reaches the specified value. until the value is reached. The test force is applied for 2 to 8 seconds, and the test force is maintained for 10 to 15 seconds. 5.4 During the entire test process, the test device should avoid collision and vibration. 5.5 If possible, perform at least three hardness measurements on one specimen. 5.6 The distance from the center of any indentation to the edge of the specimen should not be less than 2.5 times the average value of the indentation diagonal. The center distance between two adjacent indentations should not be less than 3 times the average value of the indentation diagonal. If two adjacent indentations are of different sizes, the interval should be based on the average value of the larger indentation diagonal. 5.7 The indenter should be calibrated frequently to keep it in good condition. If the indentation shape is not Rules, which may indicate that the indenter is damaged. If it is indeed damaged after inspection, then this test should be invalidated and a new indenter should be replaced. 5.8 Measure the length of the two diagonals of the indentation and calculate the Vickers hardness value as the arithmetic mean of the two readings or find the Vickers hardness value in Appendix A.
6 Representation of results
Record the arithmetic mean of the hardness values ​​obtained. The hardness value should be rounded to ten integers of HV according to the digital rounding rules in Appendix C of GB1.1-81 "General Provisions for the Preparation of Standards in Guidelines for Standardization Work". 7 Test report
The test report should include the following:
a ． Number of this standard;
Details necessary to identify the test specimen,
Test results;
Any operations not specified in this standard or optional; d.
Details of any phenomenon that may affect the results. e.
Note: There is no universal method for accurately converting Vickers hardness to other hardness values. Therefore, such conversion should be avoided unless reliable data for conversion can be obtained through comparative tests.
GB7997-87
Appendix A
Table of Vickers hardness values ​​(HV) of cemented carbide
(Supplement)
Test The test force F is 9.807N (1kgf) ~ 490.3N (50kgf) see Table A1 ~ A7 Table A1 The test force is 9.807N (1kgf))
Indentation diagonal
Average value d
Indentation diagonal
Average value &
Indentation diagonal
1Average value ratio
.0.0386
Indentation diagonal
Average value d
Indentation diagonal
Average value
Indentation diagonalbzxz.net
Average value d
Indentation diagonal
Average value
GB7997—87
Test force F is 29.42N (3kgf)
Indentation diagonal
Average value&
Indentation diagonal
Average value d
Indentation diagonal
Average value d
Indentation diagonal
Average value
Indentation diagonal
Average value d
GB7997-87
Test force F is 49.03N (5kgf)
Indentation diagonal
Average Value d
indentation diagonal
average value d
: 0.0896
indentation diagonal
average value
indentation diagonal
average value
indentation diagonal
average value&
GB7997—87
test force F is 98.07N (10kgf)
indentation diagonal
average value&
indentation diagonal
average value d
indentation diagonal
average value ratio
indentation Diagonal
Average value d
Indentation diagonal
Average value
GB7997—87
Test force F is 196.1N (20kgf)
Indentation diagonal
Average value
Indentation diagonal
Average value
Indentation diagonal
Average value
Indentation diagonal
Average value d
Indentation diagonal
Average value
GB7997—87
Table A6 Test force F is 294.2N (30kgf) Vickers
Indentation diagonal
Average value d
Indentation diagonal
Average value
Indentation diagonal
Average value
Additional instructions:
Indentation diagonal
Average value#
This standard was drafted by Zhuzhou Cemented Carbide Factory. The main drafters of this standard are Zhou Guangliang and Lin Daohui. GB7997
Test force F is 490.3N (50kgf)
Indentation diagonal
Average value d
Indentation diagonal
Average value
Indentation diagonal
Average value d
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