GB 4909.8-1985 Bare wire test method Hardness test Brinell method

This test method is applicable to the determination of the hardness of copper, aluminum and their alloy conductors. GB 4909.8-1985 Bare wire test method Hardness test Brinell method GB4909.8-1985 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Test methods for bare wires
Hardness test
Brinell hardness test
The provisions of this standard are consistent with those of the international standard ISO R403 (1964). 1 Scope of application
1.1 This test method is applicable to the determination of the hardness of copper, aluminum and their alloy conductors. UDC 621.315-14
:620.178,1
GB 4909.8-85
1.2 This test method is to use a steel ball to press into the surface of the test piece under load (Figure 1), until the load is removed after a specified time (Figure 2), and measure the diameter of the positive mark on the surface of the test piece. The Brinell hardness of the conductor is calculated by the following formula: HB = -
-Brinell hardness, kgf/mm2,
Formula if!: HB-
F——test load, kgf,
-steel ball diameter, mm
d—-measured average diameter of the indentation, mm.
2 Test equipment
2.1 Brinell hardness testing machine shall meet the following requirements2F
aD(D-D2 -d2)
2.1.1 The load force shall be perpendicular to the sample loading table, and its deflection shall not exceed 0.2/100. Figure 2
2.1.2 The load can be increased evenly and steadily, the deviation of the test load is ±1%, and it shall remain constant within the specified time of applying the test load.
2.2 Test steel ball
2.2.1 The hardness of the steel ball should not be less than HV850. 2.2.2 The surface of the steel ball should be polished and free of surface defects. The diameter deviation should comply with the requirements of Table 1. Issued by the National Bureau of Standards on January 31, 1985
Implemented on December 1, 1985
Steel ball diameter D
GB 4909.8—85
2.3 Indentation measuring instrument with lighting device Cutting reading microscope 2.4 Standard Brinell hardness block
Self-test piece preparation
3.1 Cut a test piece of about 100 mm in length from the sample. Position
8.2 The surface of the test piece should be smooth and clean enough. If necessary, the surface of the test piece can be polished with metallographic sandpaper. 4 Test steps
4.1 Place the specimen on the sample loading platform. The upper surface of the specimen should be perpendicular to the load force. If necessary, the specimen should be fixed by appropriate methods.
Select the steel ball and test load according to Table 2. Table 2
Narrow side of specimen
F/D value
True diameter of steel ball D
Test load p
Load duration
.3 Place the selected steel ball at a suitable position on the surface of the specimen. The distance between the center of the indentation after the test and the edge of the specimen should be no less than 2.5d, and the distance between the centers of two adjacent indentations should be no less than 4d. Each specimen should be measured once in the middle and three places on both sides. 4. Start the testing machine and apply load to the surface of the specimen through the steel ball. The load should increase steadily until the specified test load value is reached. Attention should be paid to prevent impact load and vibration to avoid affecting the test results. 4.5 After reaching the specified test load, start timing and remove the load after 30s. 4.6 Measure the indentation diameter from two mutually perpendicular squares, and take the arithmetic mean of the two measured values ​​as the indentation diameter d of the test point. The accuracy of each measurement of the indentation point diameter is ±0.25% of the diameter of the test steel ball. 5 Test results and calculations Www.bzxZ.net
5.1 The test results of the specimen are the arithmetic mean of the hardness at the three test points. The hardness of each test point is calculated according to formula (1), or it can be obtained from the table in Appendix A. The calculated result is rounded to an integer when it is 100 or above, and one decimal place is retained when it is less than 100. 5.2 The test result is expressed as the Brinell hardness symbol HB, steel ball diameter D/load F/load duration t. For example, the steel ball diameter is 5mm, the load is 250kgf, the duration is 30s, and the test result is 100, which is expressed as: 6 Notes
GB4909.B—85
HB5/250/30=100
6.1 When the steel ball has residual deformation exceeding the specified deviation or is damaged after use, it should be replaced immediately and the test is invalid. The first test result after each steel ball replacement cannot be used. 6.2 Tests have shown that the Brinell hardness values ​​of most copper and copper alloys vary slightly with the steel ball diameter and the size of the test load. This should be noted in the test.
6.3 Before using the hardness tester, the loading speed should be adjusted according to the instrument manual. Generally, the following speeds can be used for adjustment: ball diameter 10mm, 1000kgf, about 5~7s;
ball diameter 5mm, 250kgf, about 2~4s;
ball diameter 2.5mm, 62.5kgf, about 1~2ss
6.4 There is no accurate conversion relationship between various hardness values, so it is not appropriate to use the conversion value as the test result. 6.5 The α side size of the test piece should not be less than 10 times the indentation depth. The indentation depth can be calculated according to formula (2): h=
indentation diameter
d 1, 2dg
Under load F (kgf) = 10D\
Brinell hardness number
GB 4909.8—85
Appendix A
(reference)
diameter of jade mark
dio, 2d, or
under load F(kg)=10 D°
Brinell hardness number
True indentation diameter
Under load F(kgf)=10D*
di0.2ds or
Brinell hardness number
Indentation diameter
Under load F(kgf)=10D
Brinell hardness number
GB4909.8--85
Indentation diameter
do, 2dg war
Under load F(kf) 10D2
Brinell hardness number
Lelang diameter
u, 2da
Under load F (kg) = 10D
Brinell hardness number
True diameter of compression
dn.2ds or
Under load F (kgF) = 10D
Brinell hardness number
GB 4909.8—86
Pressure capsule diameter
p10, 2dg
Under load F (kgf) = [D\
Brinell hardness number
Pressure value diameter
Under load F
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