This standard specifies the test methods for interlayer resistance, coating adhesion and stacking coefficient of electrical steel. This standard is applicable to the test of interlayer resistance, coating adhesion and stacking coefficient of electrical steel. GB/T 2522-1988 Test method for interlayer resistance, coating adhesion and stacking coefficient of electrical steel sheets (strips) GB/T2522-1988 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Magnetic sheet and strip- Methods of measurement of interlaminatio nresistance and iamination factorand coat adhesiveness
UDC 669.14- 41
:621.317.3
GB 2522-88
Replaces GB2522-81
This standard refers to and adopts the international standard IEC404-2 (1978) "Test methods for magnetic and physical properties of electrical steel sheets (strips)". 1 Subject content and scope of application
This standard specifies the test methods for interlaminatio nresistance, coating adhesion and stacking factor of electrical steel. This standard is applicable to the test of interlaminar resistance, coating adhesion and stacking factor of electrical steel. 2 Test method for interlayer resistance
2.1 Definition of interlayer resistance
Interlayer resistance is a parameter that describes the insulation performance of electrical steel sheet (strip) coating, and its definition is as follows: Rs=A. (
Wherein: Rs——interlayer resistance, .mm2/piece; -The total area of ​​10 poles (=1000), mm2; A
1——The average value of 6 test currents, A. Note: For the derivation of the formula, see Appendix A.
2.2 Test range and conditions
2.2.1·The test range of interlayer resistance: 20~3.5×10*mm2/piece. 2.2.2 Test temperature: 20±15℃.
2.3 Test specimen
2.3.1 The test specimen should be representative, with a clean, flat and free surface. Marks and scratches. 2.3.2 The sample size is 400mm in length and 150mm in width. 2.4 Test device
(1)
The single-chip interlayer resistance test device shown in Figure 1 is used. The device includes three parts: pressure, electrode, and electrical measuring instrument. The electrode is composed of 10 vertical brass rods, 5 in a row, arranged in two rows, and installed on an insulating plate. Each brass rod is covered with a spring and has a pole at the lower end. The other end consists of a drill bit and a steel plate substrate. The 10 brass rods are connected in series with a standard resistor of 5Q. Approved by the Ministry of Metallurgical Industry of the People's Republic of China in 1988-1125 4.1
Implementation on January 1, 1990
About 30Q
In the figure: Power supply
-DC power supply:
GB 2522—88
Steel plate substrate
Figure 1 Schematic diagram of interlayer resistance test
①—DC ammeter 1A, 1.0 level or higher;?——DC voltmeter 1V, 1.0 level or higher, 10008/V, drill bit—diameter 4~6mm,
Standard resistor
2.5 Test method
Made of stainless steel, surface roughness Ra higher than 0.4mm, hardness HV between 250 and 300, diameter 11.3±0.03mms
Resistance 5±0.1%2.
2.5.1 Clean the surface of the sample and place it on the test platform. 2.5.2 Slowly pressurize to 2±0.1N with a pressurizing device /mm2. 2.5.3 Increase the voltage slowly to 0.5V, and then read the ammeter indication. 2.5.4 Change the position of each sample 3 times on both the front and back sides, and calculate the average value of the 6 currents. 2.5.5 Before measuring, in order to confirm whether the pole head is in good contact with the sample surface, a blank test is required. The method is to use a finely polished copper plate instead of the sample, and apply the specified test pressure on it. When the voltmeter indicates 0.5V, the ammeter reading should not be less than 0.98A. 2.6 Calculate
The interlayer resistance value is calculated according to formula (1). wwW.bzxz.Net
3 Test method for coating adhesion
3.1 Sample
Take a sample with a length of 300mm and a width of 30mm along the rolling direction of the steel plate. 3.2 Test method
Bend the sample tightly around a brass tower cylinder with diameters of 10, 20, and 30 mm in sections by 180°, check the cracking and peeling of the inner surface coating, and rate it according to Table 1. Bending radius
Performance level
No peeling
GB 2522--88
Slight peeling
Note: The concept of slight peeling is explained as follows for oriented silicon steel and non-oriented silicon steel: 20
No peeling
Slight peeling
(1) Oriented silicon steel: Straighten the sample after bending. If there is a small amount of peeling visible to the naked eye, it is judged as slight peeling. 30
No shedding
Slight shedding
(2) Non-oriented silicon steel: After bending, straighten the sample, stick it with transparent adhesive tape and then tear it off, stick it on white paper and observe. If there is coating powder sticking to it, it can be judged as slightly shedding. 4 Test method of stacking coefficient
4.1 Definition of stacking coefficient S (%)
The percentage of the ratio of the theoretical thickness calculated from the mass, density, length and width of the silicon steel sheet sample to the stacking thickness measured under a certain pressure is the stacking coefficient.
Where: m
The mass of the sample, kg,
The average width of the sample, m;
-The length of the sample, m;
The specified density of the corresponding grade of the sample, kg/m3, p
h —The stacking height of the sample under the specified pressure, m. 4.2 Sample
×100 %
4.2.1 The sample size is 300±0.5mm in length and 30±0.1mm in width. If it exceeds this range, the actual measured value shall prevail, but the measurement error shall not exceed ±0.1mm.
4.2.2 The number of sample pieces is determined by the sample thickness (see Table 2). 46
Sample thickness, mm
GB 2522—88
Number of sample pieces
4.2.3 Half of the non-oriented silicon steel sheet sample is longitudinal and half is transverse, and all the oriented silicon steel sheet samples are longitudinal. 4.2.4 The sample edge should be free of burrs, and the surface should be clean without knots and scratches. 4.3 Test method
4.3.1 Accurately measure the mass of the sample, and the measurement error shall not exceed ±0.1%. 4.3.2 Stack the specimens neatly and place them symmetrically between two parallel clamps with moderate hardness and smooth surface, as shown in Figure 2. 4.3.3 Apply a pressure of 0.34N/mm in the direction perpendicular to the surface of the specimen. If there are other force requirements, they can be negotiated and decided by the supply and demand parties.
4.3.4 Measure the stacking thickness h1, h2, h3, and h4 at both ends of the diagonal of the specimen near the clamps, as shown in Figure 3. Take the arithmetic mean h as the stacking thickness of the specimen. The measurement error of the stacking thickness shall not exceed ±0.01mm. Figure 2 Schematic diagram of the stacking state of the specimen
Figure 3 Top view of the stacking state of the specimen
4.4 Calculation
The stacking coefficient S is calculated according to formula (2).
GB 2522--88
Appendix A
Derivation of interlayer resistance formula
Reference)
According to Ohm's law, the loop equation for testing interlayer resistance is as follows: R+Rn
Where: u-voltage meter reading, adjusted to 0.5VRn-resistance of one coating at the nth electrode, α, R-resistance in series on each pole, specified as 5±0.1%2. Since each piece of electrical steel has two coatings, according to the definition of interlayer resistance: Rs
That is: R=
Substituting formula (A2) into formula (A1) gives:
Solving formula (A3) gives:
Additional notes:
This standard was drafted by the Information and Standards Research Institute of the Ministry of Metallurgical Industry and Wuhan Iron and Steel Company. The main drafters of this standard are Zhao Yusheng and Yuan Furong. t
.（A1)
（A3)
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