ASTM A341/A341M-00(2005)e1
(Test Method)Standard Test Method for Direct Current Magnetic Properties of Materials Using D-C Permeameters and the Ballistic Test Methods
Standard Test Method for Direct Current Magnetic Properties of Materials Using D-C Permeameters and the Ballistic Test Methods
SIGNIFICANCE AND USE
Permeameters require the use of yokes to complete the magnetic circuit and are therefore inherently less accurate than ring test methods. Refer to Test Method A 596/A 596M for further details on ring test methods. However, when testing certain shapes as bars or when magnetic field strength in excess of 200 Oe [15.9 or more kA/m] are required, permeameters are the only practical means of measuring magnetic properties.
This test method is suitable for specification acceptance, service evaluation, research and development and design.
When the test specimen is fabricated from a larger sample and is in the same condition as the larger sample, it may not exhibit magnetic properties representative of the original sample. In such instances the test results, when viewed in context of past performance history, will be useful for judging the suitability of the material for the intended application.
SCOPE
1.1 This test method provides dc permeameter tests for the basic magnetic properties of materials in the form of bars, rods, wire, or strip specimens which may be cut, machined, or ground from cast, compacted, sintered, forged, extruded, rolled, or other fabricated materials. It includes tests for determination of the normal induction under symmetrically cyclically magnetized (SCM) conditions and the hysteresis loop (B-H loop) taken under conditions of rapidly changing or steep wavefront reversals of the direct current magnetic field strength.
1.2 This test method shall be used in conjunction with Practice A 34/A 34M.
1.3 This test method covers a range of magnetic field strength in the specimen from about 0.05 Oe [4 A/m] up to above 5000 Oe [400 kA/M] through the use of several permeameters. The separate permeameters cover this test region in several overlapping ranges.
1.4 Normal induction and hysteresis properties may be determined over the flux density range from essentially zero to intrinsic saturation for most materials.
1.5 Recommendations of the useful magnetic field strength range for each of the permeameters are shown in Table 1 . Also, see Sections 3 and 4 for general limitations relative to the use of permeameters.
1.6 The symbols and abbreviated definitions used in this test method appear with Fig. 1 and in appropriate sections of this document. For the official definitions, see Terminology A 340. Note that the term flux density used in this document is synonymous with the term magnetic induction.
1.7 Warning—Mercury has been designated by EPA and many state agencies as a hazardous material that can cause central nervous system, kidney, and liver damage. Mercury, or its vapor, may be hazardous to health and corrosive to materials. Caution should be taken when handling mercury and mercury-containing products. See the applicable product Material Safety Data Sheet (MSDS) for details and EPA’s website (http://www.epa.gov/mercury/faq.htm) for additional information. Users should be aware that selling mercury or mercury-containing products, or both, in your state may be prohibited by state law.
1.8 The values and equations stated in customary cgs-emu and inch-pound or SI units are to be regarded separately as standard. Within this standard, SI units are shown in brackets except for the sections concerning calculations where there are separate sections for the respective unit systems. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in nonconformance with this standard.
1.9 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
TABLE 1 Permeameters PermeameterUseful Magnetic Field Strength RangeAH Measuring
DeviceB Reluct...
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´1
Designation:A341/A341M–00 (Reapproved 2005)
Standard Test Method for
Direct Current Magnetic Properties of Materials Using D-C
Permeameters and the Ballistic Test Methods
This standard is issued under the fixed designationA341/A341M; the number immediately following the designation indicates the year
of original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.
A superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
´ NOTE—Mercury warning was editorially added in January 2009.
1. Scope central nervous system, kidney, and liver damage. Mercury, or
its vapor, may be hazardous to health and corrosive to
1.1 This test method provides dc permeameter tests for the
materials.Cautionshouldbetakenwhenhandlingmercuryand
basicmagneticpropertiesofmaterialsintheformofbars,rods,
mercury-containing products. See the applicable product Ma-
wire, or strip specimens which may be cut, machined, or
terial Safety Data Sheet (MSDS) for details and EPA’s website
ground from cast, compacted, sintered, forged, extruded,
(http://www.epa.gov/mercury/faq.htm) for additional informa-
rolled, or other fabricated materials. It includes tests for
tion. Users should be aware that selling mercury or mercury-
determination of the normal induction under symmetrically
containingproducts,orboth,inyourstatemaybeprohibitedby
cyclically magnetized (SCM) conditions and the hysteresis
state law.
loop (B-H loop) taken under conditions of rapidly changing or
1.8 The values and equations stated in customary cgs-emu
steep wavefront reversals of the direct current magnetic field
and inch-pound or SI units are to be regarded separately as
strength.
standard. Within this standard, SI units are shown in brackets
1.2 This test method shall be used in conjunction with
except for the sections concerning calculations where there are
Practice A34/A34M.
separate sections for the respective unit systems. The values
1.3 This test method covers a range of magnetic field
stated in each system may not be exact equivalents; therefore,
strength in the specimen from about 0.05 Oe [4 A/m] up to
each system shall be used independently of the other. Combin-
above 5000 Oe [400 kA/M] through the use of several
ingvaluesfromthetwosystemsmayresultinnonconformance
permeameters. The separate permeameters cover this test
with this standard.
region in several overlapping ranges.
1.9 This standard does not purport to address all of the
1.4 Normal induction and hysteresis properties may be
safety concerns, if any, associated with its use. It is the
determined over the flux density range from essentially zero to
responsibility of the user of this standard to establish appro-
intrinsic saturation for most materials.
priate safety and health practices and determine the applica-
1.5 Recommendations of the useful magnetic field strength
2 bility of regulatory limitations prior to use.
range for each of the permeameters are shown in Table 1 .
Also,seeSections3and4forgenerallimitationsrelativetothe
2. Referenced Documents
use of permeameters.
2.1 ASTM Standards:
1.6 Thesymbolsandabbreviateddefinitionsusedinthistest
A34/A34M Practice for Sampling and Procurement Testing
method appear with Fig. 1 and in appropriate sections of this
of Magnetic Materials
document. For the official definitions, see Terminology A340.
A340 Terminology of Symbols and Definitions Relating to
Note that the term flux density used in this document is
Magnetic Testing
synonymous with the term magnetic induction.
A596/A596M Test Method for Direct-Current Magnetic
1.7 Warning—Mercury has been designated by EPA and
Properties of Materials Using the Ballistic Method and
many state agencies as a hazardous material that can cause
Ring Specimens
2.2 IEC Standard:
This test method is under the jurisdiction of ASTM Committee A06 on Publication 60404-4, Ed. 2.0 Magnetic Materials – Part 4:
MagneticPropertiesandisthedirectresponsibilityofSubcommitteeA06.01onTest
Methods.
Current edition approved Nov. 1, 2005. Published November 2005. Originally
approved in 1969. Last previous edition approved in 2000 as A341/A341M–00. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
DOI: 10.1520/A0341_A0341M-00R05E01. contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
The boldface numbers in parentheses refer to a list of references at the end of Standards volume information, refer to the standard’s Document Summary page on
this standard. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
´1
A341/A341M–00 (2005)
TABLE 1 Permeameters
A
Magnetizing Coil
Useful Magnetic Field Strength Range
H Measuring Reluctance
Permeameter Surrounds References
B
Device Compensation
Oe kA/m Specimen
Babbit 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)
C
Fahy Simplex 0.1/300 0.008/24 HC no no (1,4,5,6,7)
Fahy Simplex
100/2500 8/200 HC no no (1,3)
C
Super H adapter
Full range 0.05/1400 0.004/112 HC yes yes (1,8)
High H 100/5000 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 60404-4
IEC Type B 0.1/630 0.008/50 RCC no no IEC 60404-4
Isthmus 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, HC yes yes (15)
Saturation 100/4000 8/320 HC no yes (5,16,17)
A
Although the permeameters are capable of being used at the lower end of the measurement range, the measurement accuracy is reduced.
B
I—magnetizing current; HC—fixed H coil; FC—flip coil; HP—Hall probe; RCC—Rogowski-Chattock coil.
C
Fahy permeameters require a standard of known magnetic properties for calibration of the H coil.
ring test methods. Refer to Test Method A596/A596M for
further details on ring test methods. However, when testing
certainshapesasbarsorwhenmagneticfieldstrengthinexcess
of200Oe[15.9ormorekA/m]arerequired,permeametersare
the only practical means of measuring magnetic properties.
3.2 Thistestmethodissuitableforspecificationacceptance,
service evaluation, research and development and design.
3.3 When the test specimen is fabricated from a larger
sampleandisinthesameconditionasthelargersample,itmay
not exhibit magnetic properties representative of the original
sample. In such instances the test results, when viewed in
context of past performance history, will be useful for judging
NOTE 1—
the suitability of the material for the intended application.
A —Multirange ammeter (main current)
A —Multirange ammeter (hysteresis current)
4. Interferences
B—Flux density test position for Switch S
4.1 In general, permeameters do not maintain a uniform
F—Electronic Integrator
H—Magnetic field strength test position for Switch S
magneticfieldineithertheaxialorradialdirectionsaroundthe
N —Magnetizing coil
1 test specimen. The field gradients in both of these directions
N —Flux sensing (B) coil
willdifferinthevariouspermeameters.AlsotheH-sensingand
N —Magnetic field strength sensing coil
B-sensing coils of the different permeameters are not identical
R —Main current control rheostat
in area, in turns, or in length or identically located. Although
R —Hysteresis current control rheostat
test specimens are prepared to have uniform physical cross
S —Reversing switch for magnetizing current
S —Shunting switch for hysteresis current control rheostat section, they may have undetected nonuniform magnetic prop-
S —Integrator selector switch
erties radially or axially along the specimen length adjacent to
SP—Specimen
the H or B coils. Some permeameters may also introduce
FIG. 1 Basic Circuit Using Permeameter
clamping strains into the test specimen. For the above reasons
test results obtained on a test specimen with one type per-
Methods of Measurement of D.C. Magnetic Properties of
meameter may not agree closely with those obtained on the
Iron and Steel, IEC, 1995
same test specimen using another type of permeameter.
2.3 Other Documents:
5 5. Apparatus
NIST Circular No. 74, pg. 269
NIST Scientific Paper 117, SPBTA 5.1 Because of the differences in physical construction of
the various permeameters listed in Table 1, no standard list of
3. Significance and Use
components is given. When used with a particular type of
3.1 Permeameters require the use of yokes to complete the permeameter, the components should conform to the general
magnetic circuit and are therefore inherently less accurate than requirementslistedbelow.Abasicschematicofapermeameter
is shown in Fig. 1.
5.2 Permeameter—The particular permeameter used shall
Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
be of high quality construction. The yokes should be made of
4th Floor, New York, NY 10036.
high permeability alloy such as oriented or nonoriented silicon
Available from National Institute of Standards and Technology (NIST), 100
Bureau Dr., Stop 3460, Gaithersburg, MD 20899-3460. iron or nickel-iron alloy, although low carbon steel or iron is
´1
A341/A341M–00 (2005)
TABLE 2 Number of Test Strips
acceptable in certain instances. The preferred yolk dimensions
are listed in the appended references (see Table 1). Deviations Nominal Thickness Gage Number of
in. mm Number Strips
fromthesedimensionsshouldbesuchthattheyolkisoperating
0.0100 to 0.0250 0.254 to 0.635 32 to 24, incl 12
at or below the point of maximum permeability for the highest
0.0280 to 0.0435 0.711 to 1.105 23 to 19, incl 8
test flux densities encountered. Yoke construction may consist 0.0500 and over 1.27 and over 18 and thicker 4
of either stacked laminations or stripwound C cores suitably
bolted or adhesive bonded together.
measurement should be made on the upper two-thirds of the
5.3 Power Supply—The magnetizing current shall be sup-
scale. Analog integrators must have drift adjust circuitry and
plied by either storage batteries or dc power supplies. Bipolar
−6
thedriftshouldnotexceed100Maxwell-turns[10 Wb-turns]
programmable linear power supplies have been found to be
per minute on the most sensitive range. It is also desirable that
wellsuitedforthisuse.Thesourceofdccurrentmustbestable,
theintegratorhaveappropriatescalingcircuitrytopermitdirect
have negligible ripple and be capable of quickly returning to
reading of either flux (f) or flux density (B). Ballistic galva-
the stable state after switching. When programmable power
nometersormovingcoilfluxmetersarepermittedprovidedthe
suppliesareused,eitherdigitaloranalogprogrammingsignals
1% full-scale accuracy requirement is met. Such devices
are permissible provided that equal but opposite polarity
requireadditionalcircuitrynotshowninFig.1.Detailsmaybe
current cycling is possible.
found in the appropriate references appended to this test
5.4 Main-Current-Control Rheostats, R —When used,
method.
these rheostats must have sufficient power rating and heat-
5.11 B Coils—Prewound fixed flux sensing coils are often
dissipating capacity to handle the voltage and largest test
used. When used, the cross-sectional area enclosed by the
current and must contain sufficient resistance to limit the test
secondary winding and number of turns must be known to be
currentstothoserequiredforthelowestmagneticfieldstrength
better than 0.5%.
to be used.
5.12 Magnetic Field Strength Measuring Devices—Certain
5.5 Hysteresis-Current-Control Rheostats, R —When used,
permeameters do not or cannot use the magnetizing current to
these rheostats must have the same characteristics as the
determine the magnetic field strength accurately. Such per-
main-current control rheostats.
meameters instead use stationary H coils, flip coils, or Hall
5.6 Main-Current Ammeter, A —Magnetizing current mea-
probes. When such devices are used, they shall be capable of
surement shall be conducted using a digital ammeter or
determiningtheapparentmagneticfieldstrengthtoaccuracyof
combination of a digital voltmeter and precision shunt resistor
1.0% or better.
with an overall accuracy of better than 0.25% when the
magnetic field strength will be determined from the current. In
6. Test Specimens
those permeameters where the magnetic field strength is
6.1 Test specimen area shall normally be determined from
determined by other means, such as Hall probes or H coils,
mass, length, and density as indicated in 9.1 and 10.1. When
lower accuracy analog instruments can be used. In such
thetestspecimenismachinedorgroundtohaveaverysmooth
permeameters, the ammeter is used to prevent excessive
surface, the physical dimensions obtained from micrometer
currents from being applied and, based on past experience, to
measurements may be used to calculate the cross-sectional
roughly establish the required magnetic field strength.
area.
5.7 Hysteresis-Current Ammeter, A —The requirements of
6.2 Test specimens in bar form may be of round, square, or
5.6 shall apply. In general, a separate ammeter is not required.
rectangular cross-sectional shape. In some permeameters the
5.8 Reversing Switch, S —When nonprogrammable dc cur-
1 bar specimen may be a half round or any shape having a
rent sources such as storage batteries are used, a current
uniform cross-sectional area. Certain permeameters must have
reversing switch is required. The reversing switch should be
a good magnetic joint between the ends of the test specimen
either a high quality knife switch, mechanical or electrical
and the permeameter yoke or pole faces. Pole shoes may be
solenoid-operatedcontractorsormercuryswitcheshavinghigh
necessary to create this joint. Generally, to achieve a good
current rating and the ability to maintain uniform contact
magnetic joint, the test specimen must be of square or
resistance of equal magnitude in both current directions.
rectangular cross section and must be machined or ground to
Switches with contact bounce or other multiple contacting
have straight and parallel surfaces. For permeameters using
behavior on make or break must be avoided. Because of the
specimens butted to pole pieces, the specimen ends must be
presence of leakage currents in the open condition, solid state
smooth and parallel.
relays are not permitted.
6.3 When the material is in flat-rolled form and is to be
5.9 Hysteresis Switch, S —This single pole switch must
evaluated as half transverse-half longitudinal, the specimen
conform to the same requirements as the reversing Switch, S .
shall be sheared to have strips in multiples of four in accor-
5.10 Integrator, F—Because of their superior accuracy, dance with Table 2. When material is to be eval
...
This document is not anASTM standard and is intended only to provide the user of anASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation:A 341/A341M–00 (Reapproved 2005) Designation:A341/A341M–00
´1
(Reapproved 2005)
Standard Test Method for
Direct Current Magnetic Properties of Materials Using D-C
Permeameters and the Ballistic Test Methods
ThisstandardisissuedunderthefixeddesignationA341/A341M;thenumberimmediatelyfollowingthedesignationindicatestheyear
of original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.
A superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
´ NOTE—Mercury warning was editorially added in January 2009.
1. Scope
1.1 Thistestmethodprovidesdcpermeametertestsforthebasicmagneticpropertiesofmaterialsintheformofbars,rods,wire,
or strip specimens which may be cut, machined, or ground from cast, compacted, sintered, forged, extruded, rolled, or other
fabricatedmaterials.Itincludestestsfordeterminationofthenormalinductionundersymmetricallycyclicallymagnetized(SCM)
conditionsandthehysteresisloop(B-Hloop)takenunderconditionsofrapidlychangingorsteepwavefrontreversalsofthedirect
current magnetic field strength.
1.2 This test method shall be used in conjunction with Practice A34/A34M.
1.3 This test method covers a range of magnetic field strength in the specimen from about 0.05 Oe [4A/m] up to above 5000
Oe [400 kA/M] through the use of several permeameters.The separate permeameters cover this test region in several overlapping
ranges.
1.4 Normal induction and hysteresis properties may be determined over the flux density range from essentially zero to intrinsic
saturation for most materials.
1.5 RecommendationsoftheusefulmagneticfieldstrengthrangeforeachofthepermeametersareshowninTable1 .Also,see
Sections 3 and 4 for general limitations relative to the use of permeameters.
1.6 The symbols and abbreviated definitions used in this test method appear with Fig. 1 and in appropriate sections of this
document.Fortheofficialdefinitions,seeTerminologyA340.Notethatthetermfluxdensityusedinthisdocumentissynonymous
with the term magnetic induction.
1.7The values and equations stated in customary cgs-emu and inch-pound or SI units are to be regarded separately as standard.
Within this standard, SI units are shown in brackets except for the sections concerning calculations where there are separate
sectionsfortherespectiveunitsystems.Thevaluesstatedineachsystemmaynotbeexactequivalents;therefore,eachsystemshall
be used independently of the other. Combining values from the two systems may result in nonconformance with this standard.
1.8
1.7 Warning—Mercury has been designated by EPA and many state agencies as a hazardous material that can cause central
nervous system, kidney, and liver damage. Mercury, or its vapor, may be hazardous to health and corrosive to materials. Caution
should be taken when handling mercury and mercury-containing products. See the applicable product Material Safety Data Sheet
(MSDS) for details and EPA’s website ( http://www.epa.gov/mercury/faq.htm) for additional information. Users should be aware
that selling mercury or mercury-containing products, or both, in your state may be prohibited by state law.
1.8 Thevaluesandequationsstatedincustomarycgs-emuandinch-poundorSIunitsaretoberegardedseparatelyasstandard.
Within this standard, SI units are shown in brackets except for the sections concerning calculations where there are separate
sectionsfortherespectiveunitsystems.Thevaluesstatedineachsystemmaynotbeexactequivalents;therefore,eachsystemshall
be used independently of the other. Combining values from the two systems may result in nonconformance with this standard.
1.9 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory
limitations prior to use.
This test method is under the jurisdiction ofASTM CommitteeA06 on Magnetic Properties and is the direct responsibility of SubcommitteeA06.01 on Test Methods.
Current edition approved Nov. 1, 2005. Published November 2005. Originally approved in 1969. Last previous edition approved in 2000 as A341/A341M–00.
The boldface numbers in parentheses refer to a list of references at the end of this standard.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
´1
A341/A341M–00 (2005)
2. Referenced Documents
2.1 ASTM Standards:
A34/A34M Practice for Sampling and Procurement Testing of Magnetic Materials
A340 Terminology of Symbols and Definitions Relating to Magnetic Testing
A596/A596M Test Method for Direct-Current Magnetic Properties of Materials Using the Ballistic Method and Ring
Specimens
2.2 IEC Standard:
Publication 60404-4, Ed. 2.0 Magnetic Materials – Part 4: Methods of Measurement of D.C. Magnetic Properties of Iron and
Steel, IEC, 1995
2.3 Other Documents:
NIST Circular No. 74, pg. 269
NIST Scientific Paper 117, SPBTA
3. Significance and Use
3.1 Permeameters require the use of yokes to complete the magnetic circuit and are therefore inherently less accurate than ring
test methods. Refer to Test MethodA596/A596M for further details on ring test methods. However, when testing certain shapes
asbarsorwhenmagneticfieldstrengthinexcessof200Oe[15.9ormorekA/m]arerequired,permeametersaretheonlypractical
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 larger sample and is in the same condition as the larger sample, it may not
exhibitmagneticpropertiesrepresentativeoftheoriginalsample.Insuchinstancesthetestresults,whenviewedincontextofpast
performance history, will be useful for judging the suitability of the material for the intended application.
4. Interferences
4.1 In general, permeameters do not maintain a uniform magnetic field in either the axial or radial directions around the test
specimen.Thefieldgradientsinbothofthesedirectionswilldifferinthevariouspermeameters.AlsotheH-sensingand B-sensing
coils of the different permeameters are not identical in area, in turns, or in length or identically located.Although test specimens
arepreparedtohaveuniform physical cross section, theymayhaveundetectednonuniformmagneticpropertiesradiallyoraxially
along the specimen length adjacent to the H or B coils. Some permeameters may also introduce clamping strains into the test
specimen. For the above reasons test results obtained on a test specimen with one type permeameter may not agree closely with
those obtained on the same test specimen using another type of permeameter.
5. Apparatus
5.1 Because of the differences in physical construction of the various permeameters listed in Table 1, no standard list of
components is given. When used with a particular type of permeameter, the components should conform to the general
requirements listed below. A basic schematic of a permeameter is shown in Fig. 1.
ForreferencedASTMstandards,visittheASTMwebsite,www.astm.org,orcontactASTMCustomerServiceatservice@astm.org.ForAnnualBookofASTMStandards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036.
Available from National Institute of Standards and Technology (NIST), 100 Bureau Dr., Stop 3460, Gaithersburg, MD 20899-3460.
TABLE 1 Permeameters
A
Magnetizing Coil
Useful Magnetic Field Strength Range
H Measuring Reluctance
Permeameter Surrounds References
B
Device Compensation
Oe kA/m Specimen
Babbit 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)
C
Fahy Simplex 0.1/300 0.008/24 HC no no (1,4,5,6,7)
Fahy Simplex
100/2500 8/200 HC no no (1,3)
C
Super H adapter
Full range 0.05/1400 0.004/112 HC yes yes (1,8)
High H 100/5000 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 60404-4
IEC Type B 0.1/630 0.008/50 RCC no no IEC 60404-4
Isthmus 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, HC yes yes (15)
Saturation 100/4000 8/320 HC no yes (5,16,17)
A
Although the permeameters are capable of being used at the lower end of the measurement range, the measurement accuracy is reduced.
B
I—magnetizing current; HC—fixed H coil; FC—flip coil; HP—Hall probe; RCC—Rogowski-Chattock coil.
C
Fahy permeameters require a standard of known magnetic properties for calibration of the H coil.
´1
A341/A341M–00 (2005)
NOTE 1—
A —Multirange ammeter (main current)
A —Multirange ammeter (hysteresis current)
B—Flux density test position for Switch S
F—Electronic Integrator
H—Magnetic field strength test position for Switch S
N —Magnetizing coil
N —Flux sensing (B) coil
N —Magnetic field strength sensing coil
R —Main current control rheostat
R —Hysteresis current control rheostat
S —Reversing switch for magnetizing current
S —Shunting switch for hysteresis current control rheostat
S —Integrator selector switch
SP—Specimen
FIG. 1 Basic Circuit Using Permeameter
5.2 Permeameter—The particular permeameter used shall be of high quality construction. The yokes should be made of high
permeability alloy such as oriented or nonoriented silicon iron or nickel-iron alloy, although low carbon steel or iron is acceptable
in certain instances. The preferred yolk dimensions are listed in the appended references (see Table 1). Deviations from these
dimensions should be such that the yolk is operating at or below the point of maximum permeability for the highest test flux
densities encountered. Yoke construction may consist of either stacked laminations or stripwound C cores suitably bolted or
adhesive bonded together.
5.3 Power Supply—The magnetizing current shall be supplied by either storage batteries or dc power supplies. Bipolar
programmable linear power supplies have been found to be well suited for this use.The source of dc current must be stable, have
negligible ripple and be capable of quickly returning to the stable state after switching. When programmable power supplies are
used, either digital or analog programming signals are permissible provided that equal but opposite polarity current cycling is
possible.
5.4 Main-Current-Control Rheostats, R —When used, these rheostats must have sufficient power rating and heat-dissipating
capacity to handle the voltage and largest test current and must contain sufficient resistance to limit the test currents to those
required for the lowest magnetic field strength to be used.
5.5 Hysteresis-Current-Control Rheostats, R —When used, these rheostats must have the same characteristics as the
main-current control rheostats.
5.6 Main-Current Ammeter, A —Magnetizing current measurement shall be conducted using a digital ammeter or combination
of a digital voltmeter and precision shunt resistor with an overall accuracy of better than 0.25% when the magnetic field strength
will be determined from the current. In those permeameters where the magnetic field strength is determined by other means, such
as Hall probes or H coils, lower accuracy analog instruments can be used. In such permeameters, the ammeter is used to prevent
excessive currents from being applied and, based on past experience, to roughly establish the required magnetic field strength.
5.7 Hysteresis-Current Ammeter, A —The requirements of 5.6 shall apply. In general, a separate ammeter is not required.
5.8 Reversing Switch, S — When nonprogrammable dc current sources such as storage batteries are used, a current reversing
switch is required. The reversing switch should be either a high quality knife switch, mechanical or electrical solenoid-operated
contractors or mercury switches having high current rating and the ability to maintain uniform contact resistance of equal
magnitude in both current directions. Switches with contact bounce or other multiple contacting behavior on make or break must
be avoided. Because of the presence of leakage currents in the open condition, solid state relays are not permitted.
5.9 Hysteresis Switch, S — This single pole switch must conform to the same requirements as the reversing Switch, S .
2 1
5.10 Integrator, F—Because of their superior accuracy, stability, and ease of operation, electronic charge integrators are the
preferred means of measuring magnetic flux. Integrators using either operational amplifier and capacitor feedback (analog
integrator) or pulse counting are permitted. The accuracy of the integrator must be better than 1% full scale. If analog display
metersareusedtoreadthevalueofflux,themeasurementshouldbemadeontheuppertwo-thirdsofthescale.Analogintegrators
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A341/A341M–00 (2005)
−6
musthavedriftadjustcircuitryandthedriftshouldnotexceed100Maxwell-turns[10 Wb-turns]perminuteonthemostsensitive
range. It is also desirable that the integrator have appropriate scaling circuitry to permit direct reading of either flux (f)orflux
density (B). Ballistic galvanometers or moving coil fluxmeters are permitted provided the 1% full-scale accuracy requirement is
met. Such devices require additional circuitry not shown in Fig. 1. Details may be found in the appropriate references appended
to this test method.
5.11 B Coils—Prewoundfixedfluxsensingcoilsareoftenused.Whenused,thecross-sectionalareaenclosedbythesecondary
winding and number of turns must be known to be better than 0.5%.
5.12 Magnetic Field Strength Measuring Devices—Certain permeameters do not or cannot use the magnetizing current to
determinethemagneticfieldstrengthaccurately.SuchpermeametersinsteadusestationaryHcoils,flipcoils,orHallprobes.When
such devices are used, they shall be capable of determining the apparent magnetic field strength to accuracy of 1.0% or better.
6. Test Specimens
6.1 Testspecimenareashallnormallybedeterminedfrommass,length,anddensityasindicatedin9.1and10.1.Whenthetest
specimenismachinedorgroundtohaveaverysmoothsurface,thephysicaldimensionsobtainedfrommicrometermeasurements
may be used to calculate the cross-sectional area.
6.2 Test specimens in bar form may be of round, squ
...
This document is not anASTM standard and is intended only to provide the user of anASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
´1
An American National Standard Designation: A 341/A 341M – 00 (Reapproved 2005)
Designation:A 341/A341M–95
Standard Test Method for
Direct Current Magnetic Properties of Materials Using D-C
Permeameters and the Ballistic Test Methods
ThisstandardisissuedunderthefixeddesignationA341/A341M;thenumberimmediatelyfollowingthedesignationindicatestheyear
of original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.
A superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
ThisstandardisissuedunderthefixeddesignationA341/A341M;thenumberimmediatelyfollowingthedesignationindicatestheyear
of original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.
A superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
´ NOTE—Mercury warning was editorially added in January 2009.
1. Scope
1.1 Thistestmethodprovidesdcpermeametertestsforthebasicmagneticpropertiesofmaterialsintheformofbars,rods,wire,
or strip specimens which may be cut, machined, or ground from cast, compacted, sintered, forged, extruded, rolled, or other
fabricatedmaterials.Itincludestestsfordeterminationofthenormalinductionundersymmetricallycyclicallymagnetized(SCM)
conditionsandthehysteresisloop(B-Hloop)takenunderconditionsofrapidlychangingorsteepwavefrontreversalsofthedirect
current magnetic field strength.
1.2 This test method shall be used in conjunction with Practice A34/A34M.
1.3 This test method covers a range of magnetic field strength in the specimen from about 0.05 Oe [4A/m] up to above 5000
Oe [400 kA/M] through the use of several permeameters.The separate permeameters cover this test region in several overlapping
ranges.
1.4 Normal induction and hysteresis properties may be determined over the flux density range from essentially zero to intrinsic
saturation for most materials.
1.5 RecommendationsoftheusefulmagneticfieldstrengthrangeforeachofthepermeametersareshowninTable1 .Also,see
Sections 3 and 4 for general limitations relative to the use of permeameters.
1.6 The symbols and abbreviated definitions used in this test method appear with Fig. 1 and in appropriate sections of this
document.Fortheofficialdefinitions,seeTerminologyA340.Notethatthetermfluxdensityusedinthisdocumentissynonymous
with the term magnetic induction.
1.7The values stated in either customary (absolute (or practical) cgs-emu and inch-pound) units or SI units are to be regarded
separately as standard. Within this test method, the SI units are shown in brackets except for the sections concerning calculations
where there are separate sections for the respective unit systems. The values stated in each system are not exact equivalents;
therefore, each system shall be used independently of the other. Combining values from the two systems may result in
nonconformance with this specification.
1.8This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory
limitations prior to use.
1.7 Warning—Mercury has been designated by EPA and many state agencies as a hazardous material that can cause central
nervous system, kidney, and liver damage. Mercury, or its vapor, may be hazardous to health and corrosive to materials. Caution
should be taken when handling mercury and mercury-containing products. See the applicable product Material Safety Data Sheet
(MSDS) for details and EPA’s website ( http://www.epa.gov/mercury/faq.htm) for additional information. Users should be aware
that selling mercury or mercury-containing products, or both, in your state may be prohibited by state law.
1.8 Thevaluesandequationsstatedincustomarycgs-emuandinch-poundorSIunitsaretoberegardedseparatelyasstandard.
Within this standard, SI units are shown in brackets except for the sections concerning calculations where there are separate
sectionsfortherespectiveunitsystems.Thevaluesstatedineachsystemmaynotbeexactequivalents;therefore,eachsystemshall
be used independently of the other. Combining values from the two systems may result in nonconformance with this standard.
ThistestmethodisunderthejurisdictionofASTMCommitteeA-6A06onMagneticPropertiesandisthedirectresponsibilityofSubcommitteeA06.01onTestMethods.
Current edition approved Feb. 15, 1995.Nov. 1, 2005. Published April 1995.November 2005. Originally published as A341–69.approved in 1969. Last previous edition
A341–89´ approved in 2000 asA341/A341M–00.
The boldface numbers in parentheses refer to a list of references at the end of this standard.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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A341/A341M–00 (2005)
1.9 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory
limitations prior to use.
2. Referenced Documents
2.1 ASTM Standards:
A34PracticeforProcurement,TestingandSamplingofMagneticMaterials 34/A34M PracticeforSamplingandProcurement
Testing of Magnetic Materials
A340 Terminology of Symbols and Definitions Relating to Magnetic Testing Testing
A596Test Method for Direct Current Magnetic Properties of Materials Using the Ballistic Method and Ring Specimens
A773Test Method for dc Magnetic Properties of Materials Using Ring and Permeameter Procedures with dc Electronic
Hysteresigraphs 596/A596M Test Method for Direct-Current Magnetic Properties of Materials Using the Ballistic Method
and Ring Specimens
2.2 IEC Standard:
Publication404-4MagneticMaterialsPart4:MethodsofMeasurementoftheD-CMagneticPropertiesofSolidSteel,IEC,1982.
Publication 60404-4, Ed. 2.0 Magnetic Materials – Part 4: Methods of Measurement of D.C. Magnetic Properties of Iron and
Steel, IEC, 1995
2.3 Other Documents:Other Documents:
NIST Circular No. 74, pg. 269
NISTCircular No. 74, pg. 269.
NISTScientific Paper 117, SPBTA
NIST Scientific Paper 117, SPBTA
Annual Book of ASTM Standards, Vol 03.04.
ForreferencedASTMstandards,visittheASTMwebsite,www.astm.org,orcontactASTMCustomerServiceatservice@astm.org.ForAnnualBookofASTMStandards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Available from American National Standards Institute, 11 Institute (ANSI), 25 W. 42nd43rd St., 13th4th Floor, New York, NY 10036.
Available from National Institute of Standards and Technology, (NIST), Gaithersburg, MD 20899.
Available from National Institute of Standards and Technology (NIST), 100 Bureau Dr., Stop 3460, Gaithersburg, MD 20899-3460.
TABLE 1 Permeameters
Useful Magnetizingc Foield Strcength
Magnetizing Coils
A
H Measuring Reluctance
Range
Permeameter Surrounds References
B
Device Comp.ensation
Specimen
Oersteds kA/M
m
Babbit 40/1 000 3 200/80 000 I, HC yes yes (1,2)
Babbit 40/1000 3.2/80 I, HC yes yes (1,2)
Burroughs 0.1/300 8/24 000 I yes yes (1,3,4,5)
Burroughs 0.1/300 0.008/24 I yes yes (1,3,4,5)
C
Fahy Simplex 0.1/300 8/24 000 HC no no (1,4,5,6,7)
C
Fahy Simplex 0.1/300 0.008/24 HC no no (1,4,5,6,7)
Fahy Simplex
100/2 500 8 000/200 000 HC no no (1,3)
C
Super H Adapter
Fahy Simplex
100/2500 8/200 HC no no (1,3)
C
Super H adapter
Full Range 0.05/1 400 4/1 100 HC yes yes (1,8)
Full range 0.05/1400 0.004/112 HC yes yes (1,8)
D
High H 100/5 000 8 000/400 000 FC yes no (1,5,7,9)
High H 100/5000 8/400 FC yes no (1,5,7,9)
D
Iliovici 0.5/500 40/400 000 I, HC yes yes (4,10,11)
Iliovici 0.5/500 0.04/400 I, HC yes yes (4,10,11)
Isthmus 100/20 000 + 8 000/1 600 000 + HC, HP no yes IEC 60404-4
IEC Type A 0.1/2500 0.008/200 HC, HP no yes IEC 60404-4
IEC Type B 0.1/630 0.008/50 RCC no no IEC 60404-4
Isthmus 100/20 000+ 8/1600+ HC, HP no no (1,4,12,13)
D
MH 0.1/300 8/2 400 FC yes yes (1,6,14)
MH 0.1/300 0.008/24 FC yes yes (1,6,14)
D
NPL 0.5/2 500 40/200 000 I, HC yes yes (15)
NPL 0.5/2500 0.04/200 I, HC yes yes (15)
Saturation 100/4 000 8 000/400 000 HC no yes (5,16,17)
Saturation 100/4000 8/320 HC no yes (5,16,17)
A
Although the permeameters are capable of being used at the lower end of the measurement range, the measurement accuracy is reduced. Best overall accuracy is
obtained for a combination of high flux density and high magnetic field strength such as is encountered in the testing of permanent magnet materials.
B
I—magnetizing current; HC—fixed H-coil; FC—flip coil; HP—Hall P probe; RCC—Rogowski-Chattock coil.
C
Fahy permeameters require a standard of known magnetic properties for calibration of the H-coil.
D
These permeameters are recommended by the International Electrotechnical Commission.
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A341/A341M–00 (2005)
NOTE 1—
A —Multirange ammeter (main current)
A —Multirange ammeter (hysteresis current)
B—Flux density test position for s Switch S
F—Electronic Integrator
H—Magnetic field strength test position for s Switch S
N —Magnetizing coil
N —Flux sensing (B) coil
N —Magnetic field strength sensing coil
R —Main current control rheostat
R —Hysteresis current control rheostat
S —Reversing switch for magnetizing current
S —Shunting switch for hysteresis current control rheostat
S —Integrator selector switch
SP—Specimen
FIG. 1 Basic Circuit Using Permeameter
3. Significance and Use
3.1 Permeameters require the use of yokes to complete the magnetic circuit and are therefore inherently less accurate than ring
test methods. Refer to Test MethodA596/A596M for further details on ring test methods. However, when testing certain shapes
asbarsorwhenmagneticfieldstrengthinexcessof200Oe[15.9ormorekA/m]arerequired,permeametersaretheonlypractical
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 larger sample and is in the same condition as the larger sample, it may not
exhibitmagneticpropertiesrepresentativeoftheoriginalsample.Insuchinstancesthetestresults,whenviewedincontextofpast
performance history, will be useful for judging the suitability of the material for the intended application.
4. Interferences
4.1 In general, permeameters do not maintain a uniform magnetic field in either the axial or radial directions around the test
specimen.Thefieldgradientsinbothofthesedirectionswilldifferinthevariouspermeameters.AlsotheH-sensingandB-sensing
coils of the different permeameters are not identical in area, in turns, or in length or identically located.Although test specimens
are prepared to have uniform physical cross section, they may have undetected nonuniform magnetic properties radially or axially
along the specimen length adjacent to the H-H or B-coils.B coils. Some permeameters may also introduce clamping strains into
thetestspecimen.Fortheabovereasonstestresultsobtainedonatestspecimenwithonetypepermeametermaynotagreeclosely
with those obtained on the same test specimen using another type of permeameter.
5. Apparatus
5.1Due to5.1 Because of the differences in physical construction of the various permeameters listed inTable 1, no standard list
of components is given. When used with a particular type of permeameter, the components should conform to the general
requirements listed below. A basic schematic of a permeameter is shown in Fig. 1.
5.2 Permeameter—The particular permeameter used shall be of high quality construction. The yokes should be made of high
permeability alloy such as oriented or nonoriented silicon iron or nickel-iron alloy, although low carbon steel or iron is acceptable
in certain instances. The preferred yolk dimensions are listed in the appended references (see Table 1). Deviations from these
dimensions should be such that the yolk is operating at or below the point of maximum permeability for the highest test flux
densities encountered.Yoke construction may consist of either stacked laminations or stripwound C-coresC cores suitably bolted
or adhesive bonded together.
5.3 Power Supply—The magnetizing current shall be supplied by either storage batteries or dc power supplies. Bipolar
programmable linear power supplies have been found to be well suited for this use.The source of dc current must be stable, have
negligible ripple and be capable of quickly returning to the stable state after switching. When programmable power supplies are
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A341/A341M–00 (2005)
used, either digital or analog programming signals are permissible provided that equal but opposite polarity current cycling is
possible.
5.4 Main-Current-Control Rheostats, R —When used, these rheostats must have sufficient power rating and heat-dissipating
capacity to handle the voltage and largest test current and must contain sufficient resistance to limit the test currents to those
required for the lowest magnetic field strength to be used.
5.5 Hysteresis-Current-Control Rheostats, R —When used, these rheostats must have the same characteristics as the
main-current control rheostats.
5.6 Main-Current Ammeter, A —Magnetizing current measurement shall be conducted using a digital ammeter or combination
of a digital voltmeter and precision shunt resistor with an overall accuracy of better than 0.25% when the magnetic field strength
will be determined from the current. In those permeameters where the magnetic field strength is determined by other means, such
as Hall probes or H-coils,H coils, lower accuracy analog instruments can be used. In such permeameters, the ammeter is used to
prevent excessive currents from being applied and, based on past experience, to roughly establish the required magnetic field
strength.
5.7 Hysteresis-Current-Ammeter, A —The requirements of 5.6 shall apply. In general, a separate
Hysteresis-Current Ammeter, A
ammeter is not required.
5.8 Reversing Switch, S — When nonprogrammable dc current sources such as storage batteries are used, a current reversing
switch is required. The reversing switch should be either a high quality knife switch, mechanical or electrical solenoid-operated
contractors or mercury switches having hig
...
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