GB/T 3657-1983 Measurement method of DC magnetic properties of soft magnetic alloys
Some standard content:
National Standard of the People's Republic of China
Measurement method of direct magnetic propertiesof soft magnetic alloys
GB 3657-83
This standard is applicable to the measurement of the basic magnetization curve and magnetic hysteresis loop of annular specimens made of soft magnetic alloys (iron-nickel, iron-cobalt-vanadium, iron-aluminum alloys, etc.) at room temperature: magnetic induction intensity B, magnetic field intensity H, magnetic permeability μ, residual magnetic induction intensity B,, coercive force He, rectangular ratio B,/Bm. Other measurement methods are allowed when the error is not greater than the measurement error. Measurement principle and circuit
1.1 According to the principle of electromagnetic induction, when the magnetizing current in the magnetizing circuit changes, the magnetic flux in the specimen also changes, and an induced electromotive force is generated at both ends of the measuring winding. The DC magnetic parameters of the specimen are determined based on the deflection of the impact galvanometer and the magnetizing current. 1.2 The principle circuit diagram of the impact method measurement device is shown in the figure below. Measurement principle circuit diagram
K1, K2, K double-pole bidirectional switch, K, Ks, K single-pole unidirectional switch R variable resistor, R2, R3, R. - resistance box, Rs - equivalent resistance of transformer secondary coil, A, A1 - DC ammeter, A2 - AC ammeter, G - impulse galvanometer, E - DC magnetizing power supply, M - standard transformer, T1 - autotransformer, T - demagnetizing transformer, N - magnetizing winding: Nz - measuring winding
National Bureau of Standards 1983-05-02 Issued
1984-03-01 Implementation
GB 3657-88
1.3 In this measuring device, the standard transformer M is used to calibrate the impulse galvanometer. The autotransformer T1 and the demagnetizing transformer T are used to demagnetize the sample.
2 Test specimen
2.1 For strips with a thickness of not less than 0.15 mm, a ring specimen is used, with an inner diameter of 32 mm, an outer diameter of 40 mm, and a thickness of 5 to 7 mm; for strips with a thickness of less than 0.15 mm, a strip with a width of 10 mm is taken along the rolling direction and rolled into a ring specimen with an inner diameter of 25 mm and an outer diameter of 32 mm.
2.2 The specimen should be flat and free of defects such as burrs and cracks. 2.3 Before heat treatment, the inner and outer diameters of the specimen are measured with a caliper with an accuracy of 0.02 mm, and the average diameter is calculated using formula (2). The specimen is weighed with a balance with a sensitivity of one thousandth of a gram, and the cross-sectional area of the specimen is calculated using formula (3). 2.4 The prepared specimen must first be heat treated. After heat treatment, the specimen should no longer be subjected to stress (impact, compression, tension, bending, vibration, etc.).
2.5Put the heat-treated sample into a sample box made of non-magnetic insulating material, evenly wind the measuring winding N2 outside the sample box, and then wind the magnetizing winding NMi.
3 Instruments and components in the measuring device
3.1 Impact galvanometer
Free vibration period is not less than 18s;
Electrical constant is not greater than 10*C/(mm·m), and current constant is not greater than 10-°A/(mm·m); 3.2 DC ammeter A and A1
A and A are multi-range ammeters with an accuracy of not less than 0.5 level, and the measuring ranges are 1mA~6A and 1mA~1A respectively. 3.3 DC magnetizing power supply E
Output voltage: 0~20V continuously adjustable,
Output voltage stability: no more than ±0.05% per minute, ripple voltage: no more than 2mV at full scale,
Output current: 0~6A.
3.4 Standard transformer M
The accuracy of the standard transformer shall not be lower than level 0.2, and the mutual inductance value can be 0.1 or 0.05H. 3.5 Sliding wire resistor R
This resistor can allow a maximum current of 6A to pass. 3.6 The resistance range of resistor box R2, R3, R
is 0~100000, the minimum step value is 0.1α, and the power is not less than 0.25W. 3.7 Resistor Rs
This resistance value is equal to the resistance value of the secondary coil of the transformer. 3.8 Instrument calibration
The instruments and meters used in this standard should be sent to the metrology department for calibration regularly. 4 Measurement stepsWww.bzxZ.net
4.1 First, calibrate the impulse galvanometer with a standard transformer. As shown in Figure 1, connect the two ends of the measuring winding Nz with the equivalent resistance of the sample measuring winding, set the conversion switches K2 and K: to position 1, close K, connect K. to M, and adjust the resistor R1 so that a current I of appropriate size passes through the primary line of the standard transformer. When the switch K is used to commutate the current, the light spot of the impulse galvanometer is deflected, and the impulse constant K of the impulse galvanometer is calculated by formula (1): 83
GB 3657--88
Where: K-
-Impact constant of impulse galvanometer, Wb/grid,-Standard mutual inductance, H,
-Current, A,
-Deflection of the light spot of the impulse galvanometer, grid. a
When measuring the constant K, the deflection of the galvanometer is averaged at three points: 1/3, 1/2, and 2/3 of the scale. The galvanometer impact constant K is related to the series resistance R3 and the parallel resistance R1 of the impact galvanometer. Adjust R3 and R4 according to the measurement requirements, and then measure the constant. 4.2 If the measurement is below the inflection point of the basic magnetization curve, the sample should be demagnetized by induction method before measurement, as shown in Figure 1. Set the switch K2K to position 2, connect the sample to the demagnetization circuit, adjust the autotransformer T, and magnetize the sample to basic saturation (exceeding the inflection point of the magnetization curve), then slowly pull out the secondary winding of the demagnetization transformer T for a distance of about 1m, then turn the secondary winding 90 degrees, and disconnect the power supply. The demagnetization time is about 20s, and the demagnetization frequency is 50Hz. 4.3 Measure the magnetic induction intensity and magnetic permeability under a given magnetic field strength. During measurement, the sample is connected to the measuring device according to Figure 1, switches K and K, are both placed in position 1, K, is placed in position 2, K is closed, K. Connect resistor R5, adjust resistor R to meet the given magnetizing current, use switch K to commutate the current, and deflect the light spot of the impact galvanometer by α. Use formulas (4), (5) and (7) to calculate the magnetic field intensity and the magnetic induction intensity and magnetic permeability of the sample under the magnetic field intensity. 4.4 When measuring under each magnetic field, first perform magnetic training under the magnetic field. The magnetic training frequency is about once per second, and the number of magnetic training times is about 7 to 10 times.
4.5 After measuring the magnetic induction intensity, measure the residual magnetic induction intensity B under the same magnetic field, use K, to cut off the power, record the number of deflection grids of the impact galvanometer αo, and use α to calculate the residual magnetic induction intensity B by substituting α into formula (6). 4.6 Under a given magnetic field, measure according to the steps in 4.3, then turn on K4. When switch K1 is quickly moved from position 1 to position 2, the impact galvanometer deflects by the number of grids αc. Adjust R2 repeatedly until αc = α/2. Substitute the indication Ic of A into formula (4) to calculate the coercive force Hc
4.7 To protect the impact galvanometer, switch K1 is turned on only when the light spot of the impact galvanometer is deflected. 5 Calculation
5.1 The average diameter of the sample is calculated using formula (2): d
Where: d-
average diameter of the sample, m,
inner diameter of the sample, m,
D-—outer diameter of the sample, m.
5.2 The cross-sectional area of the sample is calculated using formula (3): s-
Wherein: S-
-cross-sectional area of the sample, m2,
mass of the sample, kg,
density of the sample, kg/m2.
5.3 The magnetic field intensity H is calculated using formula (4):
Wherein: H
magnetizing field intensity, A/m,
number of turns of magnetizing winding;
magnetizing current, A.
（3）
（4）
GB 3657--83
5.4 The magnetic induction intensity B of the sample is calculated by formula (5): B
Where: B--magnetic induction intensity, T
N2--Number of turns of the measuring winding.
5.5 The residual magnetic induction intensity B is calculated by formula (6): B, =
Where: B,-
-residual magnetic induction intensity, T
-Number of deflection grids of the impact galvanometer, grids; Ka
K(α-2ao)
-Number of deflection grids of the power-off impact galvanometer when measuring Br, ao
The relative magnetic permeability ur of the sample is calculated by formula (7): 5.6
Wherein: μ-
Measurement error
Relative magnetic permeability
Magnetic permeability, H/m;
4 yuan month
-vacuum magnetic permeability (μa=4 yuan×10-7), H/m. X 107
If the requirements of this standard are met, the relative error of measuring magnetic induction intensity B shall not exceed ±3%, and the relative error of measuring magnetic field intensity H shall not exceed ±2%.
GB 3657—83
Appendix A
(reference)
The formulas used in this method are all in the International System of Units. If they are converted to the Gaussian System of Units, they are: 2MI
Where: K-
galvanometer impact constant, Mx/grid,
M——mutual inductance, H,
-current, A,
α1impact galvanometer deflection grid number, grid. B=
Where: B-
magnetic induction intensity, Gs;
a, ao
Where: H-
residual magnetic induction intensity, Gs
impact galvanometer deflection grid number, grid,
sample cross-sectional area, cm2
measurement of winding turns.
Magnetic field intensity, Oe
Ni——Number of turns of magnetizing winding;
Average diameter of sample, cm.
Where: u-
Magnetic permeability.
Where: d-
Inner diameter of sample, cm,
D——Outer diameter of sample, cm.
Where: m—
Mass of sample, g:
-Density of sample, g/cm3.
Additional remarks:
K(α-2αo)
This standard was proposed by the Ministry of Metallurgical Industry of the People's Republic of China. This standard was drafted by Dalian Steel Plant.
The main drafters of this standard are Yu Zhenshun, Wu Longpeng and Dong Anzhi. 86
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