1、Designation: A 596/A 596M 95 (Reapproved 2004)Standard Test Method forDirect-Current Magnetic Properties of Materials Using theBallistic Method and Ring Specimens1This standard is issued under the fixed designation A 596/A 596M; the number immediately following the designation indicates the yearof o
2、riginal 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 (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers dc ballistic testing for thedetermi
3、nation of basic magnetic properties of materials in theform of ring, toroidal, link, double-lapped Epstein cores, orother standard shapes which may be cut, stamped, machined,or ground from cast, compacted, sintered, forged, or rolledmaterials. It includes tests for normal induction and hysteresistak
4、en under conditions of steep wavefront reversals of thedirect-current magnetic field strength.1.2 This test method shall be used in conjunction withPractice A 34/A 34M.1.3 This test method is suitable for a testing range from verylow magnetic field strength up to 200 or more Oe 15.9 or morekA/m. The
5、 lower limit is determined by integrator sensitivityand the upper limit by heat generation in the magnetizingwinding. Special techniques and short duration testing mayextend the upper limit of magnetic field strength.1.4 Testing under this test method is inherently more accu-rate than other methods.
6、 When specified dimensional or shaperequirements are observed, the measurements are a goodapproximation to absolute properties. Test accuracy available isprimarily limited by the accuracy of instrumentation.1.5 This test method permits a choice of test specimen topermit measurement of properties in
7、any desired directionrelative to the direction of crystallographic orientation withoutinterference from external yoke systems.1.6 The symbols and abbreviated definitions used in this testmethod appear in Fig. 1 and Sections 5, 6, 9, and 10. For theofficial definitions see Terminology A 340. Note tha
8、t the termflux density used in this document is synonymous with the termmagnetic induction.1.7 The values stated in either customary (cgs-emu andinch-pound) units or SI units are to be regarded separately asstandard. Within this test method, the SI units are shown inbrackets except for the sections
9、concerning calculations wherethere are separate sections for the respective unit systems. Thevalues stated in each system are not exact equivalents; there-fore, each system shall be used independently of the other.Combining values from the two systems may result in noncon-formance with this method.1
10、.8 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Do
11、cuments2.1 ASTM Standards:A 34/A 34M Practice for Sampling and Procurement Test-ing of Magnetic Materials2A 340 Terminology of Symbols and Definitions Relating toMagnetic Testing2A 341/A 341M Test Method for Direct Current MagneticProperties of Materials Using dc Permeameters and theBallistic Test M
12、ethods2A 343/A 343M Test Method for Alternating-Current Mag-netic Properties of Materials at Power Frequencies Usingthe Wattmeter-Ammeter-Voltmeter Method and 25-cm Ep-stein Test Frame2A 773/A 773M Test Method for dc Magnetic Properties ofMaterials Using Ring and Permeameter Procedures withdc Electr
13、onic Hysteresigraphs21This test method is under the jurisdiction of ASTM Committee A06 onMagnetic Properties and is the direct responsibility of Subcommittee A06.01 on TestMethods.Current edition approved Oct. 1, 2004. Published October 2004. Originallyapproved in 1969. Last previous edition approve
14、d in 1999 as A 596/A 596 95(1999).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM Internation
15、al, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.2.2 IEC Standard:Publication 404-4, Magnetic MaterialsPart 4: Methods ofMeasurement of the D-C Magnetic Properties of SolidSteels, IEC, 198233. Significance and Use3.1 Test methods using suitable ring-type specim
16、ens4arethe preferred methods of determining the basic magneticproperties of a material caused by the absence of demagnetiz-ing effects and are well suited for specification acceptance,service evaluation, and research and development.3.2 Provided the test specimen is representative of the bulkmateria
17、l as is usually the case for thin strip and wire, this testis also suitable for design purposes.3.3 When the test specimen is not necessarily representativeof the bulk material such as a ring machined from a largeforging or casting, the results of this test method may not be anaccurate indicator of
18、the magnetic properties of the bulkmaterial. In such instances, the test results when viewed incontext of past performance history will be useful for judgingthe suitability of the current material for the intended applica-tion.4. Interferences4.1 This test method has several important requirements.U
19、nless adequate inside diameter to outside diameter ratios aremaintained in the test specimens, the magnetic field strengthwill be excessively nonuniform throughout the test specimenand the measured parameters cannot be represented as materialproperties.4.2 The basic quality of materials having direc
20、tionallysensitive properties cannot be tested satisfactorily with rings orlaminations. With them it is necessary to use Epstein speci-mens cut with their lengths in the direction of specific interestor to use long link-shaped or spirally wound toroidal core testspecimens whose long dimensions are si
21、milarly located. Theacceptable minimum width of strip used in such test specimensis also sensitive to the material under test. At present, it isbelieved that the grain-oriented silicon steels should have astrip width of at least 3 cm 30 mm.4.3 Unless ring specimens are large in diameter, it is diffi
22、cultto provide a sufficient number of primary turns needed to reachthe highest magnetic field strength. In general, magneticmaterials tend to have nonuniform properties throughout thebody of the test specimen; for this reason, uniformly distrib-uted test windings and uniform specimen cross-sectional
23、 areaare highly desirable to suppress nonuniform behavior to atolerable degree.5. Apparatus5.1 The apparatus shall consist of as many of the compo-nents described in 5.2-5.10 as are required to perform thedesired test. The basic circuit is shown in Fig. 1.5.2 Balance and Scales:5.2.1 The balance use
24、d to weigh the test specimen shall becapable of weighing to an accuracy of better than 0.1 %.5.2.2 The micrometer, caliper, or other length-measuringdevice used in the determination of magnetic path length andcross-sectional area shall be capable of measuring to anaccuracy of better than 0.1 %.5.3 d
25、c Power SupplyThe preferred source of dc current isa high quality linear power supply of either unipolar or bipolaroperation. The power supply must exhibit high stability andvery low ripple to achieve the most accurate results. Program-mable bipolar operational amplifier power supplies haveproven to
26、 be very satisfactory for this type of testing. Otherstable sources of dc current such as storage batteries arepermitted.5.4 Main-Current-Control Rheostat R1When nonpro-grammable sources of dc current such as storage batteries areused, rheostats must be used to control the current. Theserheostats mu
27、st have sufficient power rating and heat-dissipatingcapability to handle the largest test current without undesirablechanges in resistance and, therefore, magnetizing currentduring conduct of the test.5.5 Hysteresis-Current-Control Rheostat R2Thehysteresis-current-control rheostat, when required, mu
28、st havethe same power rating and resistance as the main-current-control rheostat.5.6 Main-Current Ammeter A1Measurement of the mag-netizing current can be accomplished with either a dc ammeteror a combination of a precision shunt resistor and dc voltmeter.The meters and shunt resistor, if used, must
29、 have an accuracyof at least 0.25 %. To improve test accuracy multirange digitalammeters or voltmeters are preferred. Autoranging capability3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036.4Lloyd, M. G., “Errors in Magnetic Testing with Ring
30、Specimens, TechnicalNews Bulletin, National Institute for Standards and Technology, Vol 5, 1909, p. 435(S108).NOTE 1A1Multirange ammeter, main-magnetizing current circuitA2Multirange ammeter, hysteresis-current circuitN1Magnetizing (primary) windingN2Flux-sensing (secondary) windingFElectronic integ
31、ratorR1Main current control rheostatR2Hysteresis current control rheostatS1Reversing switchS2Shunting switch for hysteresis current control rheostatFIG. 1 Basic Circuit Using Ring-Type CoresA 596/A 596M 95 (2004)2is desirable for convenience but is not essential for this testmethod. If analog meters
32、 are used, the ranges must be such thatall test readings are made in the upper two thirds of the scale.5.7 Hysteresis-Current Ammeter, A2The hysteresis-current measuring system shall conform to the requirements in5.6. In general, a separate measuring system is not requiredsince the main current amme
33、ter (A1) can also be used tomeasure the hysteresis current.5.8 Reversing Switch, S1Because of the low resistancenature of the magnetizing circuit, it is imperative that highquality switches be used. Changes in switch resistance uponreversal will cause deviation from the cyclically magnetizedconditio
34、n which, if excessive, will impair test accuracy andprecision. Experience has shown that mercury switches are thebest suited for this application. Knife blade switches ormechanical or electrically operated contractors can also beused provided the requirement for uniform and equal contactresistance c
35、an be maintained. Because of the presence ofleakage currents in the open condition, solid state relays are notpermitted. The difficulties inherent in the use of main currentreversing switches can be minimized by use of linear powersupplies capable of accepting a remote programming signal.Such power
36、supplies are permitted provided that the magne-tizing current is equal (to within 0.1 %) in either polarity whennormal induction testing is conducted, current reversals can beconducted with no overshoot or oscillation and the magnetizingcurrent is truly zero for the zero current programming signal.5
37、.9 Hysteresis Switch, S2(When Required)This switchshould conform to requirements in 5.8.5.10 Integrator, FBecause of their superior accuracy,stability, and ease of operation, electronic charge integratorsare the preferred means of measuring magnetic flux. Integra-tors using either operational amplif
38、ier and capacitor feedback(analog integrator) or pulse counting are permitted. The accu-racy of the integrator must be better than 1 % full scale. Ifanalog display meters are used to read the value of flux, themeasurement should be made on the upper two thirds of thescale. Analog integrators must ha
39、ve drift adjust circuitry andthe drift should not exceed 100 Maxwell-turns 106Wb-turnsper minute on the most sensitive range. It is also desirable thatthe integrator have appropriate scaling circuitry to permit directreading of either flux (f) or flux density (B). Ballistic galva-nometers or moving
40、coil fluxmeters are allowed provided the1 % full-scale accuracy requirement is met.6. Test Specimen6.1 When the test specimen represents a test lot of material,its selection shall conform to the requirements of PracticeA 34/A 34M or of an individual specification.6.2 To qualify as a test specimen su
41、itable for evaluation ofmaterial properties the effective ratio of mean diameter toradial width shall be not less than 10 to 1 (or an inside diameterto outside diameter ratio not less than 0.82). When the testspecimen has smaller ratios than the above requirements, thetest results should not be repr
42、esented as material properties butshould be called core properties because of nonuniform fluxdistribution.6.3 When link, oval-shaped, or rectangular test specimenforms are used, the requirements of 6.2 apply to the end orcorner sections where flux crowding occurs. When straight-sided test specimens
43、are very long relative to the length of thecorner or end sections, they are suitable for basic materialproperties evaluation with relatively unoriented materials pro-vided the uncertainty in determination of true-path (effective)length is less than 5 % of the total path length. When thisuncertainty
44、in path length (shortest or longest relative to themean-path length) exceeds 5 %, the test values should bereported as core properties and not basic material properties.6.4 The test specimen may be constructed of solid laminatedor strip materials and in any of the shapes described in 1.1.6.5 Test sp
45、ecimen cores made from strip may be laminated,machined, spirally wound, or Epstein specimens (the methodof selection for Epstein specimens is described in Test MethodA 343/A 343M, Appendix 3). When the material is to be testedhalf transverse and half longitudinal, the material shall be cutinto Epste
46、in strips or square laminations of adequate dimen-sional ratio.6.6 Test specimens used for basic material evaluation shallbe cut, machined, ground, slit, or otherwise formed to have across section that remains sufficiently uniform that its nonuni-formity will not materially affect the accuracy of es
47、tablishingand measuring flux density, B, or magnetic field strength, H,inthe test specimen.6.7 When required for material properties development, thetest specimen shall have received a stress relief or other heattreatment after preparation. This heat treatment is subject toagreement between manufact
48、urer and purchaser, manufacturersrecommendation, or the recommended heat treatment providedby the appropriate ASTM standard for the material. The heattreatment used shall be reported with the magnetic test results.7. Calibration of Integrator7.1 Practical operating experience has shown that provided
49、a proper warmup period is allowed, electronic integratorsrequire infrequent calibration and unlike ballistic galvanom-eters, calibration is not an integral part of this test method.When calibration is required, it can be accomplished witheither a mutual inductor or a volt-second source. Because oftheir traceability to the fundamental units of voltage and time,volt-second sources are the preferred means of calibration. Theaccuracy of either the mutual inductor or volt-second sourcemust be better than the rated full-scale accuracy of theintegrator.8. Procedu
