This standard is applicable to the measurement of magnetic parameters such as coercivity HC, DC magnetic induction intensity B and magnetic permeability μ of pure iron plates and various pure iron profiles. This standard stipulates: the coercivity HC is measured by the cast coil impact method in the solenoid; the DC magnetic induction intensity B is measured by the impact method in a 25cm double yoke permeameter or annular sample; the magnetic permeability μ and hysteresis characteristics are measured by annular samples. This standard determines: the applicable range of magnetic field intensity of the permeameter is 0.5~30kA/m; the applicable range of magnetic field intensity of the annular sample is not more than 10kA/m. GB/T 3656-1983 Measurement method of magnetic properties of pure iron for electrical engineering GB/T3656-1983 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Measurement methods of
magnetic properties of electrical ironUDC 669.12
: 621.3: 621
.317.4
GB 3656—83
This standard is applicable to the measurement of magnetic parameters such as coercivity Hc, DC magnetic induction intensity B and magnetic permeability μ of pure iron plates and various pure iron profiles.
This standard stipulates: The coercivity Hc is measured by the throwing coil impact method in the solenoid! The DC magnetic induction intensity B is measured by the impact method in the 25cm double yoke permeameter or annular sample; the magnetic permeability u and hysteresis characteristics are measured by annular samples. This standard stipulates that the applicable range of magnetic field strength of the permeometer is 0.5~30kA/m, and the applicable range of magnetic field strength of the annular sample is not more than 10kA/ma
On the premise that the test results are sufficient to reflect the quality of the product, other types of test methods can also be used for product rejection or delivery test. 1 Definition of terms
1.1 Coercive force
From the stable saturated magnetization state of the sample, the magnetic field is changed monotonically along the saturation magnetic loop, and the magnetic field strength when the magnetization intensity M decreases to zero along the saturation hysteresis loop is called coercive force, represented by Hc, and the unit is ampere per meter (A/m). 1.2 Magnetic induction intensity (hereinafter referred to as magnetic induction) The magnetic flux passing through the unit cross-sectional area of ​​the uniformly magnetized sample is called magnetic flux density, also known as magnetic induction intensity, represented by B, and the unit is Tesla (T).
1.3 Magnetic permeability
The ratio of the stable magnetic induction intensity of the sample on the basic magnetization curve under DC magnetization to the corresponding magnetic field intensity is called magnetic permeability, represented by μ. The maximum value of the ratio is called the maximum magnetic permeability, expressed in um. The unit is Henry per meter (H/m). 2 Measurement method
2.1 Coercive force H. Measurement
2.1.1 Sample
Take a pair of transverse samples from each batch of pure iron thin plates (thickness 4mm) as coercive force samples, the sample length is 200±0.3mm, the width is 20±0.2mm, and the thickness is 2~4mm. For each batch of pure iron materials (profiles), take a rod-shaped sample from any steel material, the sample length is 200±0.2mm, and the diameter is 10±0.2mm. For each batch of pure iron medium and thick plates, take a transverse sample from any steel plate, the sample length is 200±0.3mm, and the cross-sectional area is not large. The sample must be straight, the cross-sectional area is uniform, and there must be no obvious holes, burrs, rust and other defects. 2.1.2 Devices and instruments
2.1.2.1 The maximum magnetizing field generated by the solenoid
is not less than 2.5×104A/m, the magnetic field non-uniformity within the center ±150mm is not more than 0.4%, and the error of the calibration magnetic field constant is not more than 0.2%.
2.1.2.2 The DC power supply
should be selected according to the required maximum magnetizing field. A battery with very low internal resistance or a DC regulated power supply with a stability better than 0.1%/10min can be used, and it can work under impact conditions, and the output ripple voltage under load is not more than 10mV. 2.1.2.3 Current regulator
Generally, a sliding wire resistor can be used, which is required to be able to continuously adjust the current so that the magnetizing field changes smoothly within the measurement range. Issued by the National Bureau of Standards in 1983-0502bZxz.net
Implemented on 1984-03-01
2.1.2.4 Multi-range DC ammeter
Magnetoelectric type 0.5 level, or better.
2.1.2.5 Multi-range DC milliammeter
Magnetoelectric type 0.2 level, or better.
2.1.2.6 Measuring coil
GB 3656-83
The number of turns shall not be less than 1000 and shall be evenly wound on a non-magnetic insulating frame. The distance between the inner diameter of the coil frame and the surface of the sample shall not exceed 10mm, and the length of the coil shall not exceed 5% of the length of the sample. 2.1.2.7 Impact galvanometer
The electric quantity constant shall be less than 10-8Q/(mm·m), and the natural period shall not be less than 20s. If necessary, a flux integrator or other electronic integration device may also be used, and its integration accuracy is required to be better than 0.3%, and the zero drift per minute should be less than 0.2% of the full scale. 2.1.2.8 Sample fixture and measuring coil throwing device The sample fixture should ensure that the axis and geometric center of the sample coincide with the axis and geometric center of the solenoid, and the intersection angle of their axes is less than 2°. The geometric centers of the coil, sample and solenoid deviate from each other by no more than 5mm. The measuring coil throwing device should ensure that the measuring coil is thrown quickly and smoothly from the center of the sample along the axis of the solenoid to the predetermined end position, and ensure that there is no friction or impact on the sample during the throwing process. 2.1.3 Measurement
2.1.3.1 Principle circuit
Measurement of coercive force H. The principle circuit is shown in Figure 1: c1
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Figure 1 Principle circuit diagram for measuring coercive force H
E—DC power supply, A, ammeter; A2 milliammeter, CJ—screw
coil tube: PY-coil pull rod, NM-measuring coil, SY-sample, K,-galvanometer damping switch, Ks-current reversing switch, K. -milliammeter shunt switch; R, R,-current regulator, R2-galvanometer series resistor, G-impact galvanometer
To avoid the influence of the earth's magnetic field and the surrounding stray magnetic field, the solenoid axis should be perpendicular to the magnetic meridian, and there should be no ferromagnetic material within a distance of 1m around.
Operation method
When measuring, first close switches K1, K5, K. Turn on the power supply and adjust R to magnetize the sample to saturation. Usually, the saturation magnetization field is 75
GB 3656-—83
2×104A/m, and the sample is stabilized under the saturation magnetic field (usually 5 to 10 times are required), and then the current is slowly and steadily reduced from the maximum value to the minimum value (the duration is not less than 30s), and the magnetic field is not greater than 8A/m when the current is disconnected. Open K6, K, reverse, adjust R to steadily increase the current to demagnetize the sample, then open K, quickly move the coil from the center of the sample to 35±5mm outside the end of the sample, observe the deflection of the galvanometer, and take the current value when the galvanometer has no deflection as 1. And use (1) formula to calculate the coercive force value: H =KI
Where: K-solenoid constant, m
-current when the galvanometer deflection is zero, A. (1))
In actual operation, it is allowed to use interpolation method to obtain H, value. The method is to take two current values ​​​​sufficiently close to H, with I,<1.
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