This standard is applicable to the determination of Rockwell hardness (A scale) of cemented carbide. GB/T 3849-1983 Test method for Rockwell hardness (A scale) of cemented carbide GB/T3849-1983 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Hardmetals--Rockwell bardness (scale A) test method
Hardmetals--Rockwell bardness (scale A) test method This standard is applicable to the determination of hardmetal Rockwell hardness (scale A). This standard is equivalent to 1S03738/1-1982 "Hardmetal UDC 621.762.1:620.178.1 GB 3849-83~S03738/1-1982-Part 1: Test method".
Rockwell hardness test (scale A)-
The conical diamond indenter is pressed into the sample twice, and under the specified conditions, the residual indentation depth e is measured by a depth measuring device.
2 Explanation of symbols
Explanation of symbols is shown in Table 1 and the figure below.
Angle of diamond cone (120±0.5) Rwww.bzxz.net
Published by National Bureau of Standards on September 14, 1983
Radius of curvature at the top of the cone (0.2±0.002mm) Initial test force (98.07±1.96N)
Main test force (490.3N)
Total test force (98.07+490.3=588.4±3.92N) Indentation depth under the initial test force before applying the test force Increase of indentation depth under the main test force Residual increase of indentation depth under the initial test force after removing the main test force. The Grignard hardness is expressed in units of 0.002 mm. A=100 -
1984-0901 implementation
3 Preparation and requirements of samples
GB3849-83
3.1 The roughness of the test surface of the sample is Ra2μm. The thickness of the surface of the sintered sample should be ground away by at least 10.2mm. The surface roughness of the sample should be ground away in a way that minimizes the change of surface properties caused by overheating or rapid cooling. When measuring the hardness of a sample with a hill surface, its curvature radius shall not be less than 15mm. In order to measure the hardness of a sample with a curvature radius less than 15mm, a flat surface with a width of at least 3mm shall be prepared. 3.2 The thickness of the prepared sample is at least 1.6mm. 3.3 The surface of the sample on which the diamond indenter acts shall be parallel to the support surface, and the parallelism shall not exceed 10mm per 10mm length. 【mm. 4 Equipment
4.1 Use equipment that can measure 0.2HRA or better. 4.2 Diamond head The performance of the diamond indenter shall be tested on a calibrated hardness tester according to the requirements of GB2849-81 Rockwell Hardness Tester. A set of 200-inch hard alloy standard hardness blocks shall be formed. At least five indentations shall be made on each hard alloy standard hardness block, and the lower average hardness of each standard block and its difference with the calibrated hardness shall be calculated. The arithmetic mean and range of the three differences shall be calculated. If the average value does not exceed ±1.3HRA and the range of the difference does not exceed 0.6HRA, the indenter can be used. 4.3 Hard alloy standard hardness blocks shall have all or any of the following values: - Basic value: 85.5; 88.5; 91.0; 92.0; 193.0HRA. 5 Test procedures
5.1 Test procedures shall be in accordance with GB230-83, with the following amendments. 5.1.1 After the new head is installed, the first two readings shall not be used. 5.1.2 The speed of applying the test force shall be controlled so that when the hard double gauge is unloaded, the weight movement is completed within 6 to 8 hours. The time for maintaining the main test force after the pointer stops deflecting shall not exceed 2 seconds. And the main test shall be gradually removed within 2 seconds and the test force shall be retained. 5.1.3
To ensure good support for the specimen, the specimen points should be selected well. 5.1.4
* The tolerance of the Y diameter of the pre-angle of the round male should be ± 0.02mm. 187
GB3849--83
5.2 Select the hard alloy standard hardness block that is closest to the hardness value (estimated) of the specimen, and measure the hardness of Rockwell A on the standard block. The difference between the average value of this reading and the hardness value calibrated by the standard block should be within ± 0.5HRA. If the difference is less than ±0.51RA, the hardness tester and diamond tip should be inspected, and the cause of the error should be eliminated. If the difference is within ±0.5HRA, the difference should be added or subtracted from the average hardness value of the sample. 5.3 When measuring hardness, the first readings obtained shall not be used, and then 1 indentation shall be made on the sample to measure its hardness. 5.4 The distance between the center of any two adjacent indentations and the edge of the sample at the center of any indentation shall be at least 1.5mm. 5.5 Read the measured value according to the viscosity of the hardness tester. 6 Result expression
The hardness of a single sample should be the arithmetic mean of the readings after rounding according to Table 2. Table 2
Reading accuracy
Test report
The test report should include the following:
a This standard number,
Details required to identify the sample;
c. Measured Results:
All operating conditions not specified or selected in this standard; d.
e. Any conditions that have affected the results. Rounded to
More than 4
Note: There is no general method that can accurately convert Rockwell hardness to other hardnesses. Therefore, this conversion should be avoided except for reliable basis for conversion through comparative tests.
Additional notes:
This standard is proposed by the Ministry of Metallurgical Industry of the People's Republic of China. This standard was drafted by Zhuzhou Cemented Carbide. The main drafters of this standard are Wang Leiqin and Su Qiying. From the implementation of this standard, the former Ministry of Metallurgical Industry Standard YB852-75 "Cemented Carbide Rockwell Hardness Test Method" will be invalid. 188
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