Some standard content:
National Standard of the People's Republic of China
Test Method for Rockwell Hardness of Plastics
GB 9342-—8B
This standard is equivalent to the international standard ISO2039/2-1981 "Plastics - Determination of Hardness by Ball Indentation Method - Part 2, Grignard Hardness".
1 Main Contents and Applicable Applications
This standard specifies the test conditions for determining the Rockwell hardness of plastics and the Rockwell α hardness of plastics and the technical conditions of the hardness tester. This standard is applicable to the determination of plastic hardness by Rockwell hardness tester M, L, R center. It is not suitable for measuring plastic films and foam materials.
2 Reference standards
GB1039 General principles for test methods for mechanical properties of plastics GB2918 Standard environment for state adjustment and test of plastic specimens "Definition"
8.1 Rockwell hardness
Use the specified indenter to first apply the initial test force, then apply the main test force, and then return to the initial test force. The value is obtained by the difference in the penetration depth of the indenter under the action of the two initial test forces. 8.2 Scale www.bzxz.net
Indicates the type of Rockwell hardness indenter and the symbol of the test force. 4 Instruments
Greyhack hardness tester is mainly composed of a frame, an indenter, a force-applying mechanism, a hardness indicator and a timing device. 4.1 The frame
is a rigid structure. When the hardness tester is under the maximum test force, the deformation of the frame and the displacement of the specimen support structure shall not affect the Rockwell hardness by more than 0,5 Rockwell hardness graduation values. Instructions for use,
Qi S02039/2-1981, the non-application scope is not clearly specified. The appendix specifies another method for determining the Rockwell hardness using a Rockwell hardness tester.
21ISO2039/2-1981, there is no such provision. 27IS02039/219814t, the maximum allowable amount of frame deformation and specimen support structure displacement is specified. Approved by the Ministry of Chemical Industry of the People's Republic of China on May 13, 1988 874 *
1888-02-01 implementation
4,2 Wipe head
GB#842-88
It is a polished steel ball with a Vickers hardness of at least 7MN/m\, and dust, dirt, grease and oxides are not allowed to exist. The steel ball can slide freely in the shaft sleeve hole, and there should be no deformation during the test and no damage after the test. 4.9 The force-applying mechanism includes a load lever, a weight and a buffer, which can apply a test force to the pressure head. 4.8.1 Load lever The component that causes the weight of the weight and the hanging to ignite and apply a test force to the pressure head. 4.8.2 Magnetic weight The test force applied to the load lever hanging plate. The initial test force, main test force and positive head diameter of various Rockwell hardness scales are as follows: Rockwell hardness Initial test force! Main test force 1! Note: 1) The main test force and initial test force of each level should be accurate to within 2%. 4.8.8 Buffer Basic size Limit deviation The pressure head should be able to apply the test force to the sample smoothly and without impact, and the time of applying the test force should be controlled within 3 to 10 seconds. 4.4 Hardness indicator
Can measure the depth of the indenter to 0.001mm, and is an indicator of the Rockwell hardness value. The scale should be the hardness value, and each scale value is equal to 0.002mm.
4.5 Timing device
Can indicate the time when the initial test force and the main test force are all added and the test force is removed, until the hardness value is read, and the total test force is maintained. The timing range is not more than 60s, and the accuracy is ±5%. 5 Calibration
6.1 Use a level to adjust the hardness tester to the correct position. 5.2 Adjust the impactor of the Rockwell hardness tester. When operating with a test force of 980.7N without a sample, the test force action time is specified to be 4 to 5s.
5.9 The hardness tester should be calibrated regularly (usually every six months) with a standard block of known Rockwell hardness value by the Rockwell E scale. Before a large number of tests, it is necessary to use the standard blocks of R, M, and L scales for auxiliary calibration. 5.4 The hardness tester shall be calibrated regularly by the national measurement and testing department every year. p 375 +
GB e8t2-aa
6.1 The specimen shall have uniform thickness, smooth and flat surface, no bubbles, no mechanical damage and impurities, etc. 6.2 The thickness of the standard specimen shall not be less than 6mm, and the size of the specimen shall ensure that 5 points can be measured on the same surface of the specimen. The distance between the center of each measuring point and the distance to the edge of the specimen shall not be less than 10mm. Note. ① The recommended specimen size is l×b×h, mm, 50×50×6. ② When the test surface is a specimen of other shapes other than a plane, the specimen size shall be specified in the relevant product standards. 3 When the specimen cannot obtain the specified minimum thickness value, it is allowed to be composed of thin specimens of the same tree material, but the surfaces of each specimen shall be in close contact and shall not be separated by any form of surface defects. Note, the number of superimposed layers shall not exceed three. The results cannot be compared with non-superimposed specimens. 6.4 If the sample has indentation cracks or marks on the back of the sample during the test, the data will be invalid. Take another sample for testing. 1 Test steps
71 Check the sample according to the provisions in Chapter 2 of GB1039, and adjust the test environment according to Chapter 2 of GB2918. 7.2 Select an appropriate scale according to the softness of the material, and try to make the hardness value between 50 and 115. A few materials that cannot be in this range shall not exceed 125. If a material can be tested with two scales and the values obtained are both within the limit, the smaller scale shall be selected. The same scale should be used for the same material. 7.3 Select and install the workbench according to the shape and size of the sample, place the sample on the workbench, rotate the screw handwheel, and make the sample slowly contact the indenter without impact until the short pointer of the hardness indicator points to zero and the long pointer points vertically upward to B30 (CO). At this time, the initial test force of 98.07N has been applied. The deviation of the long pointer shall not exceed ±5 scale values. If the test exceeds this range, the test point should be changed and the test should be repeated.
7.4 Adjust the hardness indicator so that the long pointer points to B30, then apply the main test force steadily within 10s and maintain it for 15s, then steadily remove the main test force, and read the B scale data indicated by the long pointer after 15 hours, accurately to the scale division value. Note: When replacing the indenter, the data of the first point should be discarded. T.5 Turn the lifting screw handwheel in the opposite direction to lower the workbench and change the test point. Repeat the above operation and test 5 points per sample.
8 Result representation
8.1 Rockwell hardness value is represented by the previous academic scale and numbers. For example: HRM70 means that the Rockwell hardness value measured by the M scale is 70.
8,2 Digital display hardness tester can directly read the hardness value. For a dial hardness tester that is graduated directly according to the hardness value, the number of times the long needle passes through BO after the main test force is applied and the number of times the long pointer passes through BO after the main test force is removed should be recorded respectively and subtracted, and the readings should be read as follows:
8.2.1 If the difference is zero, the scale reading is adjusted to 100 as the hardness value. 8.2.2 If the difference is 1, the scale reading is the degree value. 8.2.8 If the difference is 2, the scale reading is reduced by 100 as the hardness value. 1.3 If necessary, it can be calculated according to formula (1):
Wu Zhong, HR——Rockwell hardness value
GB 9842-6)
HR= 130 -
e-—After removing the main test force, the indentation depth under the toughness test force, mms-band number, its value is 0.002mm.
8.4 The test results are expressed as the arithmetic mean of the single measured values at 5 points, and three significant figures are taken. 8.5 If standard deviation is required, calculate according to formula (2): (X:-x)2
Where. 3—standard deviation,
X,—single measured value
x—arithmetic mean of a group of measured values.
n——number of measurements.
9 Test report
The test report shall include the following contents:
Indicate the name, specification, source and manufacturer of the material according to this national standard, b
Shape, size and preparation method of the test specimen
Test environment temperature, humidity, state adjustment time test scale,
Average value and standard deviation of Rockwell hardness
Test date, test personnel.
. 377 *
A1 Scope of application
GB 9342--88
Agglomerate A
Determination of Rockwell α hardness
(Supplement)
This appendix specifies the method for determining Rockwell α hardness under total test force. This method is only applicable to the R scale with a diameter of 12.7 mm and a main test force of 588.4 N. It is suitable for the determination of soft materials. A2 Test steps
A2.1 Use the R scale to determine the elastic constant of the testing machine according to the following method. A2.1.1 Place a 6mm thick soft copper block on the workbench of the impact gauge, rotate the screw handwheel to make the soft copper block on the workbench contact with the indenter, and press the 3 operations to apply the initial test force. A21.2 Adjust the long pointer of the hardness indicator to CO, apply the main test force, and maintain the main test force until the long pointer is stable. Record this data.
A2.1.3 Remove the main test force and adjust the long pointer of the hardness indicator to CO again. Under the condition of keeping the workbench and the soft copper block absolutely and strictly keeping them still, repeat the operation of adding and removing the main test force for many times (at the beginning of each repetition, make sure that the long pointer of the hardness indicator is adjusted to CO under the initial test force until the reading of the hardness indicator is constant after each application of the main test force. This value is the elastic deformation constant of the instrument, with 0.002 beats per meter as the unit. A2.2 Replace the soft copper block with the specimen, gradually raise the workbench, make the specimen contact the indenter and apply the initial test force according to the operation of 7.3.
A2.3 Adjust the long pointer of the hardness indicator to CO within 10 seconds, immediately apply the main test force, and record the indenter penetration depth after 15 seconds, with 0.002 mm as the unit.
A8 Result decay
A3.1 Rockwell α hardness is obtained according to formula (A1): HR.= 150 - (hc) :
Wu Zhong: IRa Rockwell value
c-hardness tester elastic deformation constant, in units of 0.002mmh-total pressure>depth, in units of 0,002mm. A4 The relationship between Rockwell α hardness and ISO 2039/1 "Determination of hardness by plastic ball indentation method" HRa=150-
Wu Zhong: HR—Rockwell α hardness,
H—ball indentation hardness value.
A4.1 For the convenience of conversion, the relationship between HR and H in the range of -30 to 130 is shown in Figure A1; 378
Additional instructions,
GB 9342--88
Iso2039/1 Hardness, daN/mm-
This standard is under the jurisdiction of the Physical and Mechanical Test Methods Branch of the Jin Guo Plastics Standardization Technical Committee. This standard is drafted by the Ministry of Chemical Industry's Guanghua Chemical Research Institute. The main contributors to this standard are Li Lihua and Yu Xianhe.
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