1、Designation: A 341/A341M 00 (Reapproved 2005)Standard Test Method forDirect Current Magnetic Properties of Materials Using D-CPermeameters and the Ballistic Test Methods1This standard is issued under the fixed designationA341/A341M; the number immediately following the designation indicates the year
2、of 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 (e) indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Departme
3、nt of Defense.1. Scope1.1 This test method provides dc permeameter tests for thebasic magnetic properties of materials in the form of bars, rods,wire, or strip specimens which may be cut, machined, orground from cast, compacted, sintered, forged, extruded,rolled, or other fabricated materials. It in
4、cludes tests fordetermination of the normal induction under symmetricallycyclically magnetized (SCM) conditions and the hysteresisloop (B-H loop) taken under conditions of rapidly changing orsteep wavefront reversals of the direct current magnetic fieldstrength.1.2 This test method shall be used in
5、conjunction withPractice A 34/A 34M.1.3 This test method covers a range of magnetic fieldstrength in the specimen from about 0.05 Oe 4 A/m up toabove 5000 Oe 400 kA/M through the use of severalpermeameters. The separate permeameters cover this testregion in several overlapping ranges.1.4 Normal indu
6、ction and hysteresis properties may bedetermined over the flux density range from essentially zero tointrinsic saturation for most materials.1.5 Recommendations of the useful magnetic field strengthrange for each of the permeameters are shown in Table 12.Also, see Sections 3 and 4 for general limita
7、tions relative to theuse of permeameters.1.6 The symbols and abbreviated definitions used in this testmethod appear with Fig. 1 and in appropriate sections of thisdocument. For the official definitions, see Terminology A 340.Note that the term flux density used in this document issynonymous with the
8、 term magnetic induction.1.7 The values and equations stated in customary cgs-emuand inch-pound or SI units are to be regarded separately asstandard. Within this standard, SI units are shown in bracketsexcept for the sections concerning calculations where there areseparate sections for the respectiv
9、e unit systems. The valuesstated in each system may not be exact equivalents; therefore,each system shall be used independently of the other. Combin-ing values from the two systems may result in nonconformancewith this standard.1.8 This standard does not purport to address all of thesafety concerns,
10、 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 Documents2.1 ASTM Standards:3A 34/A 34M Practice for Sampling and Procure
11、ment Test-ing of Magnetic MaterialsA 340 Terminology of Symbols and Definitions Relating toMagnetic TestingA 596/A 596M Test Method for Direct-Current MagneticProperties of Materials Using the Ballistic Method andRing Specimens2.2 IEC Standard:Publication 60404-4, Ed. 2.0 Magnetic Materials Part 4:M
12、ethods of Measurement of D.C. Magnetic Properties ofIron and Steel, IEC, 199542.3 Other Documents:NIST Circular No. 74, pg. 2695NIST Scientific Paper 117, SPBTA53. Significance and Use3.1 Permeameters require the use of yokes to complete themagnetic circuit and are therefore inherently less accurate
13、 thanring test methods. Refer to Test Method A 596/A 596M forfurther details on ring test methods. However, when testingcertain shapes as bars or when magnetic field strength in excess1This test method is under the jurisdiction of ASTM Committee A06 onMagnetic Properties and is the direct responsibi
14、lity of SubcommitteeA06.01 on TestMethods.Current edition approved Nov. 1, 2005. Published November 2005. Originallyapproved in 1969. Last previous edition approved in 2000 as A 341/A 341M 00.2The boldface numbers in parentheses refer to a list of references at the end ofthis standard.3For reference
15、d 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.4Available from American National Standards Institute (ANSI), 25 W. 43rd St
16、.,4th Floor, New York, NY 10036.5Available from National Institute of Standards and Technology (NIST), 100Bureau Dr., Stop 3460, Gaithersburg, MD 20899-3460.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.of 200 Oe 15.9 or more kA/m
17、are required, permeameters arethe only practical means of measuring magnetic properties.3.2 This test method is suitable for specification acceptance,service evaluation, research and development and design.3.3 When the test specimen is fabricated from a largersample and is in the same condition as t
18、he larger sample, it maynot exhibit magnetic properties representative of the originalsample. In such instances the test results, when viewed incontext of past performance history, will be useful for judgingthe suitability of the material for the intended application.4. Interferences4.1 In general,
19、permeameters do not maintain a uniformmagnetic field in either the axial or radial directions around thetest specimen. The field gradients in both of these directionswill differ in the various permeameters.Also the H-sensing andB-sensing coils of the different permeameters are not identicalin area,
20、in turns, or in length or identically located. Althoughtest specimens are prepared to have uniform physical crosssection, they may have undetected nonuniform magnetic prop-erties radially or axially along the specimen length adjacent tothe H or B coils. Some permeameters may also introduceclamping s
21、trains into the test specimen. For the above reasonstest results obtained on a test specimen with one type per-meameter may not agree closely with those obtained on thesame test specimen using another type of permeameter.5. Apparatus5.1 Because of the differences in physical construction ofthe vario
22、us permeameters listed in Table 1, no standard list ofcomponents is given. When used with a particular type ofpermeameter, the components should conform to the generalrequirements listed below.Abasic schematic of a permeameteris shown in Fig. 1.5.2 PermeameterThe particular permeameter used shallbe
23、of high quality construction. The yokes should be made ofhigh permeability alloy such as oriented or nonoriented siliconiron or nickel-iron alloy, although low carbon steel or iron isacceptable in certain instances. The preferred yolk dimensionsare listed in the appended references (see Table 1). De
24、viationsfrom these dimensions should be such that the yolk is operatingat or below the point of maximum permeability for the highesttest flux densities encountered. Yoke construction may consistof either stacked laminations or stripwound C cores suitablybolted or adhesive bonded together.5.3 Power S
25、upplyThe magnetizing current shall be sup-plied by either storage batteries or dc power supplies. Bipolarprogrammable linear power supplies have been found to bewell suited for this use.The source of dc current must be stable,have negligible ripple and be capable of quickly returning tothe stable st
26、ate after switching. When programmable powersupplies are used, either digital or analog programming signalsare permissible provided that equal but opposite polaritycurrent cycling is possible.TABLE 1 PermeametersPermeameterUseful Magnetic Field Strength RangeAH MeasuringDeviceBReluctanceCompensation
27、Magnetizing CoilSurroundsSpecimenReferences2Oe kA/mBabbit 40/1000 3.2/80 I, HC yes yes (1,2)Burroughs 0.1/300 0.008/24 I yes yes (1,3,4,5)Fahy SimplexC0.1/300 0.008/24 HC no no (1,4,5,6,7)Fahy SimplexSuper H adapterC100/2500 8/200 HC no no (1,3)Full range 0.05/1400 0.004/112 HC yes yes (1,8)High H 1
28、00/5000 8/400 FC yes no (1,5,7,9)Iliovici 0.5/500 0.04/400 I, HC yes yes (4,10,11)IEC Type A 0.1/2500 0.008/200 HC, HP no yes IEC 60404-4IEC Type B 0.1/630 0.008/50 RCC no no IEC 60404-4Isthmus 100/20 000+ 8/1600+ HC, HP no no (1,4,12,13)MH 0.1/300 0.008/24 FC yes yes (1,6,14)NPL 0.5/2500 0.04/200 I
29、, HC yes yes (15)Saturation 100/4000 8/320 HC no yes (5,16,17)AAlthough the permeameters are capable of being used at the lower end of the measurement range, the measurement accuracy is reduced.BImagnetizing current; HCfixed H coil; FCflip coil; HPHall probe; RCCRogowski-Chattock coil.CFahy permeame
30、ters require a standard of known magnetic properties for calibration of the H coil.NOTE 1A1Multirange ammeter (main current)A2Multirange ammeter (hysteresis current)BFlux density test position for Switch S3FElectronic IntegratorHMagnetic field strength test position for Switch S3N1Magnetizing coilN2
31、Flux sensing (B) coilN3Magnetic field strength sensing coilR1Main current control rheostatR2Hysteresis current control rheostatS1Reversing switch for magnetizing currentS2Shunting switch for hysteresis current control rheostatS3Integrator selector switchSPSpecimenFIG. 1 Basic Circuit Using Permeamet
32、erA 341/A341M 00 (2005)25.4 Main-Current-Control Rheostats, R1When used,these rheostats must have sufficient power rating and heat-dissipating capacity to handle the voltage and largest testcurrent and must contain sufficient resistance to limit the testcurrents to those required for the lowest magn
33、etic field strengthto be used.5.5 Hysteresis-Current-Control Rheostats, R2When used,these rheostats must have the same characteristics as themain-current control rheostats.5.6 Main-Current Ammeter, A1Magnetizing current mea-surement shall be conducted using a digital ammeter orcombination of a digit
34、al voltmeter and precision shunt resistorwith an overall accuracy of better than 0.25 % when themagnetic field strength will be determined from the current. Inthose permeameters where the magnetic field strength isdetermined by other means, such as Hall probes or H coils,lower accuracy analog instru
35、ments can be used. In suchpermeameters, the ammeter is used to prevent excessivecurrents from being applied and, based on past experience, toroughly establish the required magnetic field strength.5.7 Hysteresis-Current Ammeter, A2The requirements of5.6 shall apply. In general, a separate ammeter is
36、not required.5.8 Reversing Switch, S1When nonprogrammable dc cur-rent sources such as storage batteries are used, a currentreversing switch is required. The reversing switch should beeither a high quality knife switch, mechanical or electricalsolenoid-operated contractors or mercury switches having
37、highcurrent rating and the ability to maintain uniform contactresistance of equal magnitude in both current directions.Switches with contact bounce or other multiple contactingbehavior on make or break must be avoided. Because of thepresence of leakage currents in the open condition, solid staterela
38、ys are not permitted.5.9 Hysteresis Switch, S2This single pole switch mustconform to the same requirements as the reversing Switch, S1.5.10 Integrator, FBecause of their superior accuracy,stability, and ease of operation, electronic charge integratorsare the preferred means of measuring magnetic flu
39、x. Integra-tors using either operational amplifier 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
40、-thirds of thescale. Analog integrators must have 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 d
41、ensity (B). Ballistic galva-nometers or moving coil fluxmeters are permitted provided the1 % full-scale accuracy requirement is met. Such devicesrequire additional circuitry not shown in Fig. 1. Details may befound in the appropriate references appended to this testmethod.5.11 B CoilsPrewound fixed
42、flux sensing coils are oftenused. When used, the cross-sectional area enclosed by thesecondary winding and number of turns must be known to bebetter than 0.5 %.5.12 Magnetic Field Strength Measuring DevicesCertainpermeameters do not or cannot use the magnetizing current todetermine the magnetic fiel
43、d strength accurately. Such per-meameters instead use stationary H coils, flip coils, or Hallprobes. When such devices are used, they shall be capable ofdetermining the apparent magnetic field strength to accuracy of1.0 % or better.6. Test Specimens6.1 Test specimen area shall normally be determined
44、 frommass, length, and density as indicated in 9.1 and 10.1. Whenthe test specimen is machined or ground to have a very smoothsurface, the physical dimensions obtained from micrometermeasurements may be used to calculate the cross-sectionalarea.6.2 Test specimens in bar form may be of round, square,
45、 orrectangular cross-sectional shape. In some permeameters thebar specimen may be a half round or any shape having auniform cross-sectional area. Certain permeameters must havea good magnetic joint between the ends of the test specimenand the permeameter yoke or pole faces. Pole shoes may benecessar
46、y to create this joint. Generally, to achieve a goodmagnetic joint, the test specimen must be of square orrectangular cross section and must be machined or ground tohave straight and parallel surfaces. For permeameters usingspecimens butted to pole pieces, the specimen ends must besmooth and paralle
47、l.6.3 When the material is in flat-rolled form and is to beevaluated as half transverse-half longitudinal, the specimenshall be sheared to have strips in multiples of four in accor-dance with Table 2. When material is to be evaluated in onedirection, it shall conform to this table or to the requirem
48、entsfor best test quality in a particular permeameter. For gages No.33 and thinner, the cross-sectional area shall be not less than0.31 in.2200 mm2 and not more than 0.62 in.2400 mm2.6.4 When the test specimen for strip materials is to be halftransverse and half longitudinal, the strips shall be pos
49、itionedto be composed of alternately transverse and longitudinalthroughout the specimen and a transverse strip shall be placedadjacent to the permeameters yoke or pole face.6.5 For full testing accuracy, the length and size of the testspecimen must meet the requirements of the permeameterbeing used. Generally, for most permeameters, a test specimenlength of 10 in. 0.254 m or more is required. Shorterspecimens with some permeameters will require the use ofpole-piece extensions, and may cause a reduction in testingaccuracy. Other permeam
