1、Designation: A773/A773M 01 (Reapproved 2009)A773/A773M 14Standard Test Method fordc Direct Current Magnetic Properties of Materials UsingRing and Permeameter Procedures with dc Electronic LowCoercivity Magnetic Materials Using Hysteresigraphs1This standard is issued under the fixed designation A773/
2、A773M; the number immediately following the designation indicates the yearof original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval.A superscript epsilon () indicates an editorial change since the last revision or reapp
3、roval.1. Scope1.1 This test method provides dc hysteresigraph procedures (B-H loop methods) for the determination of basic magneticproperties of materials in the form of ring, spirally wound toroidal, link, double-lapped Epstein cores, or other standard shapes thatmay be cut, stamped, machined, or g
4、round from cast, compacted, sintered, forged, or rolled materials. It includes tests for normalinduction and hysteresis loop determination taken under conditions of continuous sweep magnetization. Rate of sweep may bevaried, either manually or automatically at different portions of the curves during
5、 tracing. Total elapsed time for tracing a hysteresisloop is commonly 10 to 120 s per loop. measurement.1.2 The equipment and procedures described in this test method are most suited for soft and semi-hard materials with intrinsiccoercivity less than about 100 Oersteds 8 kA/M. Materials with higher
6、intrinsic coercivities should be tested according to TestMethod A977/A977M.1.3 The values stated in either SI units or inch-pound units and equations stated in customary (cgs-emu and inch-pound) or SIunits are to be regarded separately as standard. Within this standard, SI units are shown in bracket
7、s. The values stated in eachsystem may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from thetwo systems may result in non-conformancenonconformance with thethis standard.1.4 This standard does not purport to address all of the safety con
8、cerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2A34/A34M Practice for Sampling and Procur
9、ement Testing of Magnetic MaterialsA340 Terminology of Symbols and Definitions Relating to Magnetic TestingA341/A341M Test Method for Direct Current Magnetic Properties of Materials Using D-C Permeameters and the Ballistic TestMethodsA343/A343M Test Method for Alternating-Current Magnetic Properties
10、 of Materials at Power Frequencies Using Wattmeter-Ammeter-Voltmeter Method and 25-cm Epstein Test FrameA596/A596M Test Method for Direct-Current Magnetic Properties of Materials Using the Ballistic Method and Ring SpecimensA977/A977M Test Method for Magnetic Properties of High-Coercivity Permanent
11、Magnet Materials Using HysteresigraphsE691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method2.2 Other:IEC Publication 404-4:60404-4 Ed 2.2 Part 4: Magnetic MaterialsPart 4: Methods of Measurement of dcd.c. MagneticProperties of Iron and Steel (1995)Magnetic
12、ally Soft Materials (2008)33. Terminology3.1 DefinitionsThe terms and symbols used in this test method are defined in Terminology A340.1 This test method is under the jurisdiction of ASTM Committee A06 on Magnetic Properties and is the direct responsibility of Subcommittee A06.01 on Test Methods.Cur
13、rent edition approved May 1, 2009Oct. 1, 2014. Published August 2009October 2014. Originally approved in 1980. Last previous edition approved in 20012009 asA773/A773M01. 01 (2009). DOI: 10.1520/A0773_A0773M-01R09.10.1520/A0773_A0773M-14.2 For referencedASTM standards, visit theASTM website, www.astm
14、.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3 Available from American National Standards Institute, 25 W. 43rd St., 4th Floor, New York, NY 10036.This document is not a
15、n ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate.
16、In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States14. Summary of Test Method4.1 As in making most magnetic measurements,
17、a A specimen is wound with an excitinga magnetizing winding (the primary)primary winding) and a search coilwinding (the secondary) secondary winding) for measuring the change in flux. When anexcitinga magnetizing current, I, is applied to the primary winding, a magnetic field, H, is produced in the
18、coil, and this coil. Thisin turn produces magnetic flux in the specimen. In uniform specimens specimen and the changing flux induces a voltage in thesecondary winding which is integrated with respect to time using a fluxmeter. In specimens with uniform cross-sectional area thatdo not contain air gap
19、s, such as ring samples, rings, all of the excitingmagnetizing current is used to magnetize the specimen, andH is proportional to I in accordance with the following equation:H 5KI (1)where:H = magnetic field strength, Oe A/m;I = current in the exciting coil A; andI = current in the magnetizing windi
20、ng A; andK = constant determined by the number of primary turns the magnetic path length of the specimen and system of units.4.1.1 The magnetic flux may be determined by integration of the instantaneous electromotive force that is induced in thesecondary coilwinding when the flux is increased or dec
21、reased by a varying H. The instantaneous voltage, e, is equal to:e 52NK 1 ddt (2)e 52N K1ddt (2)or5 1K1N*edtwhere:dt = time differential,N = number of turns, andN = number of secondary turns,K1 = 10 8 for cgs-emu system, or K1 = 1 for SI system.K1 = 10 8 for cgs-emu system, or K1 = 1 for SI system,
22、ande = instantaneous voltage in the secondary winging, V.The flux can be obtained if edt can be determined. This can be accomplished by several means, as described in ASTM STP526. (1) 4 The most common method uses an electronic integrator consisting of a high-gain dc an operational amplifier withres
23、istive-capacitive feedback. The relationship to capacitive feedback. Some fluxmeters employ analog to digital edtconversionis:and digital integration techniques. The output voltage of the integrator is given by:E 5 1RC*edt (3)where:E = output voltage, V;R = input resistance of the integrator in the
24、secondary circuit, ; andC = the feedback capacitance, F.By combining the two equations:5ERCK1Nor E 5NK1RC (4)If the voltage,The instantaneous value E, is applied to the Y axis of anflux X-Yis recorder, thethus proportional Yto deflectionof the pen is proportional to the flux, .the integrated voltage
25、 which can be recorded in various ways.4.1.2 MeasurementsMeasurement of magnetic field strength and flux by the hysteresigraph method is illustrated in the blockdiagram of Fig. 1. The system consists of a magnetizing power source, an excitinga magnetizing current controller, an electronicflux integr
26、ator, and a data recorder. As excitingmagnetizing current is applied to the coil, primary winding, a voltage proportionalto I is produced across the shunt current measuring resistor which is connected in series with the primary coil.winding.This voltagedetermines is proportional to the value of H.4
27、The boldface numbers in parentheses refer to a list of references at the end of this standard.A773/A773M 1424.1.3 In the testing of hard magnetic materials, or soft magnetic materials in the form of wire, bars or rods, or materials whichcannot be sufficiently magnetized in ring form, or which are an
28、isotropic, it is usually necessary to use a permeameter. This is shownin the block diagram of Fig. 2. When using permeameters, the value of H in the gap is generally not proportional to I that flowsthrough the exciting coilmagnetizing winding of the yoke. In these cases, the value of H is determined
29、 by integration of theelectromotive force that is induced in an H coil -coil (or Chattock potentiometer) or from the signal developed by a Hall probewhich is placed near the specimen. When using an H coil, -coil, the determination of H is accomplished with an H integrator inexactly the same manner a
30、s that used to determine flux with the B integrator described in 3.14.1. When using a Hall sensor, theH values are determined from the voltage output which is linearized to be proportional to H. In some cases, the H versus Irelationship may be sufficiently linear from 0 to the coercive field strengt
31、h (Hc) of the material under test. In such cases, it isacceptable to determine the second quadrant of the hysteresis loop by determining H from the value of I in the exciting winding.5. Significance and Use5.1 Hysteresigraph testing permits Hysteresigraphs permit more rapid and efficient collection
32、of normal induction and dchysteresis (B-H loop) data as compared to the point by point ballistic Test Methods A341/A341M and A596/A596M. The accuracyand precision of testing is comparable to the ballistic methods. Hysteresigraphs are particularly desirable for testing of semihardand hard magnetic ma
33、terials where either the entire second quadrant (demagnetization curve) or entire hysteresis loop is of primaryconcern.high measurement point density offered by computer-automated systems is often required for computer aided design ofelectrical components such as transformers, motors, and relays.5.2
34、 Hysteresigraphs are particularly desirable for testing of semihard and hard magnetic materials, where either the entiresecond quadrant (demagnetization curve) or entire hysteresis loop is of primary concern. Test Method A977/A977M describes thespecial requirements for accurate measurement of hard (
35、permanent magnet) materials.5.3 Hysteresigraphs are not recommended for measurement of initial permeability of materials with high magnetic permeabilitysuch as nickel-iron, amorphous, and nanocrystalline materials due to errors associated with integrator drift; in these cases, TestMethod A596/A596M
36、is a more appropriate method.5.4 Provided the test specimen is representative of the bulk sample or lot, this test method is well suited for design, specificationacceptance, service evaluation, and research and development.6. Interferences6.1 Test methods using suitable ring-type specimens are the p
37、referred methods for determining the basic magnetic propertiesof a material. When conducting tests on ring specimens, this test method covers a range of magnetic field strengths from about0.01 Oe 0.8 A/m up to about 1000 Oe 80 kA/m or more depending on the specimen dimensions, number of primary turn
38、s,available magnetizing power, and the ability to remove heat generated in the primary winding. However, this test method hasseveral important requirements. Unless adequatethe inside diameter to outside diameter ratios are maintained in the test specimens,the ratio or ring specimens is greater than
39、0.82, the magnetic field strength will be excessively nonuniform throughoutin the testmaterial and the measured parameters cannot be represented as material properties. The basic quality of materials havingdirectionaldirectionally sensitive properties cannot be tested satisfactorily with punched rin
40、gs or laminations. With them ringspecimens. With such materials it is necessary to use Epstein specimens cut with their lengths in the direction of specific interestFIG. 1 Block Diagram of Ring Test ApparatusA773/A773M 143or to use long link-shaped5 or spirally wound core test specimens whose long d
41、imensions are similarly oriented. toroidal core testspecimens. The acceptable minimum width of strip used in such test specimens is also sensitive to varies with the material undertest.At present, it is believed recommended that the grain-oriented silicon steels should have a strip width of at least
42、 3 cm 30 mm.UnlessWhen ring specimens are large, it is difficult to provide sufficient magnetizing turns or current-carrying capacity to reachhigh magnetic field strengths. magnetic field strengths above about 1000 Oe 80 kA/m. In general, magnetic materials tend to havenonuniform properties througho
43、ut the body of the test specimens; forspecimens. For this reason, uniformly distributed testwindings and uniform specimen cross-sectional area are highly desirable to average nonuniform behavior to a tolerabledegree.behavior.6.2 When conducting permeameter tests on bars, rods, and other appropriate
44、specimens, this test method covers a range ofmagnetic field strengths from about 0.05 Oe 4 A/m up to about 20 000 Oe 1600 kA/m or more, depending on the specimengeometry and the particular permeameter (measuring fixture) that is used. In general, the lower limit of magnetic field strength isdetermin
45、ed by the area-turns of the H coil (or the sensitivity of the Hall probe if it is used), the sensitivity of the integrator, andthe sensitivities of the measuring and recording components. The upper limitationlimit in magnetic field strength is determined bythe type of permeameter appropriate for the
46、 specimen, the power supply, and the heat generated in the yoke windings.Recommendations of the useful range of magnetic field strength for the various permeameters are shown in Table 1. Other typesmay be used with appropriate precautions.6.2.1 In general, permeameters do not maintainproduce a unifo
47、rm magnetic field in either the axial or radial directions aroundthe test specimen. The field gradients in both of these directions will differ in the various permeameters. Also the H-sensing-coilsand B-sensing coils -coils of the different permeameters are not identical in area, in turns, or in len
48、gth or identically located.Although test specimens are prepared to have uniform physical cross section, they may still have undetected nonuniform magneticproperties radially or axially along the specimen length adjacent to the H or B coils. Some permeameters may also introduceclamping strainsstresse
49、s into the test specimen. For these reasons test results obtained on a test specimen with one type ofpermeameter may not compare closely with those obtained on the same specimen from another type permeameter, and both maydiffer from more precise testing methods.permeameter type.6.2.2 The limitation in the B measurement by this test method is determined by the number of turns onsecondary (B thespecimen, the cross-sectional area, the permeability, and the sensitivities of the ) turns on the specimen, the specimencross-sectional area, the permeabi
