ASTM A773/A773M-01(2009)
(Test Method)Standard Test Method for dc Magnetic Properties of Materials Using Ring and Permeameter Procedures with dc Electronic Hysteresigraphs
Standard Test Method for dc Magnetic Properties of Materials Using Ring and Permeameter Procedures with dc Electronic Hysteresigraphs
SIGNIFICANCE AND USE
Hysteresigraph testing permits more rapid and efficient collection of dc hysteresis (B-H loop) data as compared to the point by point ballistic Test Methods A 341/A 341M and A 596/A 596M. The accuracy and precision of testing is comparable to the ballistic methods. Hysteresigraphs are particularly desirable for testing of semihard and hard magnetic materials where either the entire second quadrant (demagnetization curve) or entire hysteresis loop is of primary concern.
Provided the test specimen is representative of the bulk sample or lot, this test method is well suited for design, specification acceptance, service evaluation and research and development.
SCOPE
1.1 This test method provides dc hysteresigraph procedures (B-H loop methods) for the determination of basic magnetic properties of materials in the form of ring, toroidal, link, double-lapped Epstein cores, or other standard shapes that may be cut, stamped, machined, or ground from cast, compacted, sintered, forged, or rolled materials. It includes tests for normal induction and hysteresis taken under conditions of continuous sweep magnetization. Rate of sweep may be varied, either manually or automatically at different portions of the curves during tracing. Total elapsed time for tracing a hysteresis loop is commonly 10 to 120 s per loop.
1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. 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 non-conformance with the standard.
1.3 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.
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Designation: A773/A773M − 01(Reapproved 2009)
Standard Test Method for
dc Magnetic Properties of Materials Using Ring and
Permeameter Procedures with dc Electronic
Hysteresigraphs
This standard is issued under the fixed designationA773/A773M; 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.
1. Scope A343/A343MTest Method for Alternating-Current Mag-
netic Properties of Materials at Power Frequencies Using
1.1 This test method provides dc hysteresigraph procedures
Wattmeter-Ammeter-Voltmeter Method and 25-cm Ep-
(B-H loop methods) for the determination of basic magnetic
stein Test Frame
properties of materials in the form of ring, toroidal, link,
A596/A596MTest Method for Direct-Current Magnetic
double-lappedEpsteincores,orotherstandardshapesthatmay
Properties of Materials Using the Ballistic Method and
be cut, stamped, machined, or ground from cast, compacted,
Ring Specimens
sintered,forged,orrolledmaterials.Itincludestestsfornormal
2.2 Other:
induction and hysteresis taken under conditions of continuous
IEC Publication 404-4:Magnetic Materials—Part 4: Meth-
sweep magnetization. Rate of sweep may be varied, either
odsofMeasurementofdcMagneticPropertiesofIronand
manually or automatically at different portions of the curves
Steel (1995)
during tracing. Total elapsed time for tracing a hysteresis loop
is commonly 10 to 120 s per loop.
3. Summary of Test Method
1.2 The values stated in either SI units or inch-pound units
3.1 Asinmakingmostmagneticmeasurements,aspecimen
are to be regarded separately as standard. The values stated in
is wound with an exciting winding (the primary) and a search
each system may not be exact equivalents; therefore, each
coil(thesecondary)formeasuringthechangeinflux.Whenan
system shall be used independently of the other. Combining
exciting current, I, is applied to the primary winding, a
values from the two systems may result in non-conformance
magnetic field, H, is produced in the coil, and this in turn
with the standard.
produces magnetic flux φ in the specimen. In uniform speci-
1.3 This standard does not purport to address all of the
mens that do not contain air gaps, such as ring samples, all of
safety concerns, if any, associated with its use. It is the
the exciting current is used to magnetize the specimen, and H
responsibility of the user of this standard to establish appro-
is proportional to I in accordance with the following equation:
priate safety and health practices and determine the applica-
H 5 KI (1)
bility of regulatory limitations prior to use.
where:
2. Referenced Documents
H = magnetic field strength, Oe [A/m];
2.1 ASTM Standards:
I = current in the exciting coil A; and
A34/A34MPractice for Sampling and Procurement Testing
K = constantdeterminedbythenumberofprimaryturnsthe
of Magnetic Materials
magnetic path length of the specimen and system of
A341/A341MTest Method for Direct Current Magnetic
units.
Properties of Materials Using D-C Permeameters and the
3.1.1 The magnetic flux may be determined by integration
Ballistic Test Methods
of the instantaneous electromotive force that is induced in the
secondary coil when the flux is increased or decreased by a
This test method is under the jurisdiction of ASTM Committee A06 on
varying H. The instantaneous voltage, e, is equal to:
MagneticPropertiesandisthedirectresponsibilityofSubcommitteeA06.01onTest
dφ
Methods.
e52NK (2)
Current edition approved May 1, 2009. Published August 2009. Originally
dt
approved in 1980. Last previous edition approved in 2001 as A773/A773M–01.
or
DOI: 10.1520/A0773_A0773M-01R09.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on Available from American National Standards Institute, 25 W. 43rd St., 4th
the ASTM website. Floor, New York, NY 10036.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
A773/A773M − 01 (2009)
FIG. 1 Block Diagram of Ring Test Apparatus
3.1.3 In the testing of hard magnetic materials, or soft
φ5 edt
*
K N magnetic materials in the form of wire, bars or rods, it is
usually necessary to use a permeameter. This is shown in the
where:
block diagram of Fig. 2. When using permeameters, the value
dt = time differential,
of H in the gap is generally not proportional to I that flows
N = number of turns, and
through the exciting coil of the yoke. In these cases, the value
−8
K =10 for cgs-emu system, or K =1 for SI system.
1 1
of H is determined by integration of the electromotive force
thatisinducedinan Hcoil(orChattockpotentiometer)orfrom
The flux φ can be obtained if ∫edt can be determined. This
the signal developed by a Hall probe which is placed near the
can be accomplished by several means, as described in ASTM
specimen. When using an H coil, the determination of H is
STP 526. (1) The most common method uses an electronic
accomplished with an H integrator in exactly the same manner
integrator consisting of a high-gain dc amplifier with resistive-
asthatusedtodeterminefluxwiththe Bintegratordescribedin
capacitive feedback. The relationship to ∫ edt is:
3.1. When using a Hall sensor, the H values are determined
from the voltage output which is proportional to H. In some
E5 edt (3)
*
cases, the H versus I relationship may be sufficiently linear
RC
from 0 to the coercive field strength (H ) of the material under
c
where:
test. In such cases, it is acceptable to determine the second
E = output voltage, V;
quadrant of the hysteresis loop by determining H from the
R = input resistance of the integrator in the secondary
value of I in the exciting winding.
circuit, Ω; and
C = the feedback capacitance, F.
4. Significance and Use
By combining the two equations:
4.1 Hysteresigraph testing permits more rapid and efficient
ERC φNK collection of dc hysteresis (B-H loop) data as compared to the
φ5 or E5 (4)
point by point ballistic Test Methods A341/A341M and A596/
K N RC
A596M.Theaccuracyandprecisionoftestingiscomparableto
If the voltage, E, is applied to the Y axis of an X-Y recorder,
the ballistic methods. Hysteresigraphs are particularly desir-
the Y deflection of the pen is proportional to the flux, φ.
ablefortestingofsemihardandhardmagneticmaterialswhere
3.1.2 Measurements of magnetic field strength and flux by
either the entire second quadrant (demagnetization curve) or
thehysteresigraphmethodisillustratedintheblockdiagramof
entire hysteresis loop is of primary concern.
Fig. 1. The system consists of a magnetizing power source, an
4.2 Provided the test specimen is representative of the bulk
exciting current controller, an electronic flux integrator, and a
sample or lot, this test method is well suited for design,
data recorder. As exciting current is applied to the coil, a
specification acceptance, service evaluation and research and
voltage proportional to I is produced across the shunt resistor
development.
whichisconnectedinserieswiththeprimarycoil.Thisvoltage
determines the value of H.
5. Interferences
5.1 Test methods using suitable ring-type specimens are the
preferred methods for determining the basic magnetic proper-
The boldface numbers in parentheses refer to a list of references at the end of
this standard. ties of a material. However, this test method has several
A773/A773M − 01 (2009)
FIG. 2 Block Diagram of Permeator Test Apparatus
important requirements. Unless adequate inside diameter to strength for the various permeameters are shown in Table 1.
outside diameter ratios are maintained in the test specimens, Other types may be used with appropriate precautions.
the magnetic field strength will be excessively nonuniform
5.2.1 In general, permeameters do not maintain a uniform
throughout the test material and the measured parameters
magneticfieldineithertheaxialorradialdirectionsaroundthe
cannot be represented as material properties. The basic quality
test specimen. The field gradients in both of these directions
of materials having directional sensitive properties cannot be
willdifferinthevariouspermeameters.Alsothe H-sensingand
tested satisfactorily with punched rings or laminations. With
B-sensing coils of the different permeameters are not identical
them it is necessary to use Epstein specimens cut with their
in area, in turns, or in length or identically located. Although
lengths in the direction of specific interest or use long
test specimens are prepared to have uniform physical cross
link-shaped or spirally wound core test specimens whose long
section, they may have undetected nonuniform magnetic prop-
dimensions are similarly oriented. The acceptable minimum
erties radially or axially along the specimen length adjacent to
width of strip used in such test specimens is also sensitive to
the H or B coils. Some permeameters may also introduce
the material under test. At present, it is believed the silicon
clamping strains into the test specimen. For these reasons test
steels should have a strip width of at least 3 cm [30 mm].
resultsobtainedonatestspecimenwithonetypeofpermeame-
Unless ring specimens are large, it is difficult to provide
ter may not compare closely with those obtained on the same
sufficient magnetizing turns or current-carrying capacity to
specimen from another type permeameter, and both may differ
reach high magnetic field strengths. In general, magnetic
from more precise testing methods.
materials tend to have nonuniform properties throughout the
5.2.2 The limitation in the B measurement by this test
body of the test specimens; for this reason, uniformly distrib-
method is determined by the number of turns on the specimen,
uted test windings and uniform specimen cross-sectional area
the cross-sectional area, the permeability, and the sensitivities
are highly desirable to average nonuniform behavior to a
of the B integrator and X-Y recorder. In general, normal
tolerable degree.
induction and hysteresis data may be determined from a flux
−5
linkage corresponding to 1000 Maxwell turns [10 Weber
5.2 When conducting permeameter tests on bars, rods, and
turns] to an upper induction that corresponds to the intrinsic
otherappropriatespecimens,thistestmethodcoversarangeof
saturation for most materials.
magnetic field strengths from about 0.05 Oe [4 A/m] up to
5.2.3 Some permeameters use compensation coils and re-
about 20000 Oe [1600 kA/m] or more, depending on the
quirecontinualadjustmentofthecurrentflowingthroughthese
specimen geometry and the particular permeameter that is
coils.Thismaynotbecompatiblewithcommerciallyavailable
used. In general, the lower limit of magnetic field strength is
hysteresigraphs and can be a source of significant error.
determined by the area-turns of the H coil (or the sensitivity of
theHallprobeifitisused),thesensitivityoftheintegrator,and 5.2.4 The magnetic test results, particularly for high perme-
the sensitivities of the measuring and recording components. ability alloys, may not exactly agree with test results obtained
The upper limitation in magnetic field strength is determined by the ballistic methods, Test Methods A341/A341M and
by the type of permeameter appropriate for the specimen, the A596/A596M.Thisisduetotheinfluenceofeddycurrentsand
power supply, and the heat generated in the yoke windings. the different nature of the magnetizing waveform between
Recommendations of the useful range of magnetic field hysteresigraph and ballistic testing.
A773/A773M − 01 (2009)
TABLE 1 Permeameters Recommended for Use With
7. Test Specimens for Ring-Type Measurements
Hysteresigraphs
7.1 The specifications in 7.2-7.8 cover the general case for
NOTE 1—Other permeameters may be suitable for use with dc hyster-
specimens in which magnetic field strength is proportional to
esigraphswhereappropriatemodificationsaremade.RefertoTestMethod
the exciting current, that is, H= kI.
A341/A341M for other permeameters.
7.2 When the test specimen represents a test lot of material,
Permeameter Magnetic Field Strength Range H Measurement
Device
its selection shall conform to the requirements of Practice
Oe kA/m
A34/A34M or of an individual specification.
Babbit (2, 3) 40/100 3.2/8 current, H coil
Fahy Simplex (4-6) 0.1/300 0.008/24 H coil
7.3 To qualify as a test specimen suitable for evaluation of
Fahy Simplex Super 100/2500 8/200 H coil
H Adapter (6)
material properties, the effective ratio of mean diameter to
IEC Type A 12/2500 1/200 H coil, Hall probe
radialwidthshallbenotlessthan10to1(oraninsidediameter
IEC Type B 12/620 1/50 H coil
to outside diameter ratio not less than 0.82). When the test
Isthmus (6, 7) 100/20 000 + 8/1600 + H coil, Hall probe
specimen has smaller ratios than the above requirements, the
test data should not be represented as material properties but
should be called core properties because of nonuniform flux
distribution.
6. Apparatus
7.4 When link, oval-shaped, or rectangular test specimen
forms are used, the requirements of 7.3 apply to the end or
6.1 The apparatus shall consist of as many of the compo-
corner sections where flux crowding occurs. When straight-
nents described in 6.2-6.6 as required to perform the tests.
sided test specimens are very long relative to the length of the
6.1.1 All apparatus used in this test method shall be cali-
corner or end sections, they are suitable for basic material
brated against known standards to ensure the accuracy limits
properties evaluation with relatively unoriented materials,
given below.
provided the uncertainty in determination of true-path (effec-
6.2 Balance or Scales: tive) length is less than 1% of the total path length.When this
uncertainty in path length (shortest or longest relative to the
6.2.1 The balance or scales used to weigh the test specimen
mean-path length) exceeds 1%, the test values should be
shall be capable of weighing to an accuracy of 0.2%.
reported as core properties and not basic material properties.
6.2.2 Themicrometerordimensionalmeasuringscalesused
to determine specimen dimensions for calculation of cross-
7.5 The test specimen may be constructed of solid, lami-
sectional area shall be capable of measuring to an accuracy of
nated, or strip materials and in any of the shapes described in
at least 0.1%.
1.1.
7.6 Test specimen cores made from strip may be laminated,
6.3 Magnetizing Power Source—The power source may
range from simple batteries
...
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.
An American National Standard Designation: A 773/A 773M – 01 (Reapproved 2009)
Designation:A 773/A 773M–96
Standard Test Method for
dc Magnetic Properties of Materials Using Ring and
Permeameter Procedures with dc Electronic
Hysteresigraphs
ThisstandardisissuedunderthefixeddesignationA773/A773M;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.
1. Scope
1.1 This test method provides dc hysteresigraph procedures (B-H loop methods) for the determination of basic magnetic
properties of materials in the form of ring, toroidal, link, double-lapped Epstein cores, or other standard shapes that may be cut,
stamped, machined, or ground from cast, compacted, sintered, forged, or rolled materials. It includes tests for normal induction
and hysteresis taken under conditions of continuous sweep magnetization. Rate of sweep may be varied, either manually or
automatically at different portions of the curves during tracing. Total elapsed time for tracing a hysteresis loop is commonly 10
to 120 s per loop.
1.2The values stated in either customary (cgs-emu and inch-pound) units or SI units are to be regarded separately as standard.
Within the text, the SI units are shown in brackets. The values stated in each system are not exact equivalents; therefore, each
system shall be used independently of the other. Combining values from the systems may result in nonconformance with this test
method.
1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. 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 non-conformance with the standard.
1.3 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:
A34/A34M Practice for Sampling and Procurement Testing of Magnetic MaterialsMaterials
A341/A341M TestMethodforDirect-CurrentMagneticPropertiesofMaterialsUsingdcD-CPermeametersandtheBallistic
Test Methods Methods
A343/A343M Test Method for Alternating-Current Magnetic Properties of Materials at Power Frequencies Using the
Wattmeter-Ammeter-Voltmeter Method and 25-cm Epstein Frame Test Frame
A596/A596M Test Method for Direct-Current Magnetic Properties of Materials Using the Ballistic Method and Ring
Specimens Specimens
2.2 Other:
IEC Publication 404-4: Magnetic Materials—Part 4: Methods of Measurement of dc Magnetic Properties of Iron and Steel
(1995)
3. Summary of Test Method
3.1 As in making most magnetic measurements, a specimen is wound with an exciting winding (the primary) and a search coil
(the secondary) for measuring the change in flux.When an exciting current, I, is applied to the primary winding, a magnetic field,
H, is produced in the coil, and this in turn produces magnetic flux f in the specimen. In uniform specimens that do not contain
ThistestmethodisunderthejurisdictionofASTMCommitteeA-6A06onMagneticPropertiesandisthedirectresponsibilityofSubcommitteeA06.01onTestMethods.
Current edition approved Dec. 10, 1996. Published March 1997. Originally published as A773–80. Last previous edition A773–91.
Current edition approved May 1, 2009. Published August 2009. Originally approved in 1980. Last previous edition approved in 2001 as A773/A773M–01.
Annual Book of ASTM Standards, Vol 03.04.
ForreferencedASTMstandards,visittheASTMwebsite,www.astm.org,orcontactASTMCustomerServiceatservice@astm.org.For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Available from American National Standards Institute, 1125 W. 42nd43rd St., 13th4th Floor, New York, NY 10036.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
A773/A773M–01 (2009)
airgaps,suchasringsamples,alloftheexcitingcurrentisusedtomagnetizethespecimen,andHisproportionaltoIinaccordance
with the following equation:
H 5 KI
(1)
where:
H = magnetic field strength, Oe [A/m], [A/m];
I = current in the exciting coil A,A; and
K = constant determined by the number of primary turns the magnetic path length of the specimen and system of units.
3.1.1 The magnetic flux may be determined by integration of the instantaneous electromotive force that is induced in the
secondary coil when the flux is increased or decreased by a varying H. The instantaneous voltage, e, is equal to:
df
e52NK
dt
(2)
or
f5 edt
*
K N
where:
dt = time differential,
N = number of turns, and
−8
K =10 for cgs-emu system, or K =1 for SI system.
1 1
The flux f can be obtained if |Mi *edt can be determined. This can be accomplished by several means, as described in ASTM
STP 526. (1) The most common method utilizesuses an electronic integrator consisting of a high-gain dc amplifier with
resistive-capacitive feedback. The relationship to |Mi * edt is:
E 5 edt
*
RC
(3)
where:
E = output voltage, V,;
R = input resistance of the integrator in the secondary circuit, V,V; and
C = the feedback capacitance, F.
By combining the two equations:
ERC
f5 or E
K N
fNK
RC
(4)
ERC
f5 or E
K N
fNK
RC
(4)
If the voltage, E, is applied to the Y axis of an X-Y recorder, the Y deflection of the pen is proportional to the flux, f.
3.1.2 Measurements of magnetic field strength and flux by the hysteresigraph method is illustrated in the block diagram of Fig.
1. The system consists of a magnetizing power source, an exciting current controller, an electronic flux integrator, and a data
recorder. As exciting current is applied to the coil, a voltage proportional to I is produced across the shunt resistor which is
connected in series with the primary coil. This voltage determines the value of H.
3.1.3 Inthetestingofhardmagneticmaterials,orsoftmagneticmaterialsintheformofwire,barsorrods,itisusuallynecessary
to use a permeameter. This is shown in the block diagram of Fig. 2. When using permeameters, the value of H in the gap is
generally not proportional to I that flows through the exciting coil of the yoke. In these cases, the value of H is determined by
integration of the electromotive force that is induced in an H -coilcoil (or Chattock potentiometer) or from the signal developed
by a Hall probe which is placed near the specimen. When using an H -coil,coil, the determination of H is accomplished with an
H integrator in exactly the same manner as that used to determine flux with the B integrator described in 3.1. When using a Hall
sensor, the H values are determined from the voltage output which is proportional to H. In some cases, the H versus I relationship
The boldface numbers in parentheses refer to thea list of references at the end of this test method.standard.
A773/A773M–01 (2009)
FIG. 1 Block Diagram of Ring Test Apparatus
FIG. 2 Block Diagram of Permeator Test Apparatus
may be sufficiently linear from 0 to the coercive field strength (H ) of the material under test. In such cases, it is acceptable to
c
determine the second quadrant of the hysteresis loop by determining H from the value of I in the exciting winding.
4. Significance and Use
4.1 Hysteresigraph testing permits more rapid and efficient collection of dc hysteresis (B-H loop) data as compared to the point
by point ballistic Test Methods A341 and A596A341/A341M and A596/A596M. The accuracy and precision of testing is
comparabletotheballisticmethods.Hysteresigraphsareparticularlydesirablefortestingofsemi-hardsemihardandhardmagnetic
materials where either the entire second quadrant (demagnetization curve) or entire hysteresis loop is of primary concern.
4.2 Providedthetestspecimenisrepresentativeofthebulksampleorlot,thistestmethodiswellsuitedfordesign,specification
acceptance, service evaluation and research and development.
5. Interferences
5.1 Test methods using suitable ring-type specimens are the preferred methods for determining the basic magnetic properties
of a material. However, this test method has several important requirements. Unless adequate inside diameter to outside diameter
ratiosaremaintainedinthetestspecimens,themagneticfieldstrengthwillbeexcessivelynonuniformthroughoutthetestmaterial
and the measured parameters cannot be represented as material properties. The basic quality of materials having directional
sensitive properties cannot be tested satisfactorily with punched rings or laminations. With them it is necessary to use Epstein
A773/A773M–01 (2009)
specimens cut with their lengths in the direction of specific interest or use long link-shaped or spirally wound core test specimens
whoselongdimensionsaresimilarlyoriented.Theacceptableminimumwidthofstripusedinsuchtestspecimensisalsosensitive
to the material under test. At present, it is believed the silicon steels should have a strip width of at least 3 cm [30 mm]. Unless
ring specimens are large, it is difficult to provide sufficient magnetizing turns or current-carrying capacity to reach high magnetic
field strengths. In general, magnetic materials tend to have nonuniform properties throughout the body of the test specimens; for
this reason, uniformly distributed test windings and uniform specimen cross-sectional area are highly desirable to average
nonuniform behavior to a tolerable degree.
5.2 When conducting permeameter tests on bars, rods, and other appropriate specimens, this test method covers a range of
magnetic field strengths from about 0.05 Oe [4 A/m] up to about 20000 Oe [1600 kA/m] or more, depending on the specimen
geometryandtheparticularpermeameterthatisemployed.used.Ingeneral,thelowerlimitofmagneticfieldstrengthisdetermined
bythearea-turnsofthe Hcoil(orthesensitivityoftheHallprobeifitisused),thesensitivityoftheintegrator,andthesensitivities
of the measuring and recording components. The upper limitation in magnetic field strength is determined by the type of
permeameter appropriate for the 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 types may be used with
appropriate precautions.
5.2.1 In general, permeameters do not maintain a uniform magnetic field in either the axial or radial directions around the test
specimen.Thefieldgradientsinbothofthesedirectionswilldifferinthevariouspermeameters.Alsothe H-sensingand B-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 or B coils. Some permeameters may also introduce clamping strains into the test
specimen. For these reasons test results obtained on a test specimen with one type of permeameter may not compare closely with
those obtained on the same specimen from another type permeameter, and both may differ from more precise testing methods.
5.2.2 The limitation in the B measurement by this test method is determined by the number of turns on the specimen, the
cross-sectional area, the permeability, and the sensitivities of the B integrator and X-Y recorder. In general, normal induction and
−5
hysteresis data may be determined from a flux linkage corresponding to 1000 Maxwell- turns [10 Weber turns] to an upper
induction that corresponds to the intrinsic saturation for most materials.
5.2.3 Some permeameters utilizeuse compensation coils and require continual adjustment of the current flowing through these
coils. This may not be compatible with commercially available hysteresigraphs and can be a source of significant error.
5.2.4 Themagnetictestresults,particularlyforhighpermeabilityalloys,maynotexactlyagreewithtestresultsobtainedbythe
ballistic methods, Test MethodsA341 andA596A341/A341M andA596/A596M. This is due to the influence of eddy currents
and the different nature of the magnetizing waveform between hysteresigraph and ballistic testing.
6. Apparatus
6.1 The apparatus shall consist of as many of the components described in 6.2 through 6.6 6.2-6.6 as required to perform the
tests.
6.1.1 All apparatus used in this test method shall be calibrated against known standards to ensure the accuracy limits given
below.
6.2 Balance or Scales:
6.2.1 The balance or scales used to weigh the test specimen shall be capable of weighing to an accuracy of 0.2%.
TABLE 1 Permeameters Recommended for Use With
Hysteresigraphs
NOTE 1—Other permeameters may be suitable for use with dc hyster-
esigraphswhereappropriatemodificationsaremade.RefertoTestMethod
A341/A341M for other permeameters.
Permeameter Magnetic Field Strength Range H Measurement
Device
Oe kA/m
Babbit (2, 3) 40/100 3.2/8 current, H- coil
Babbit (2, 3) 40/100 3.2/8 current, H coil
Fahy Simplex (4,5,6) 0.1/300 0.008/24 H- coil
Fahy Simplex (4-6) 0.1/300 0.008/24 H coil
Fahy Simplex Super 100/2500 8/200 H- coil
H Adapter (6)
Fahy Simplex Super 100/2500 8/200 H coil
H Adapter (6)
IEC Type A 12/2500 1/200 H- coil, Hall probe
IEC Type A 12/2500 1/200 H coil, Hall probe
IEC Type B 12/620 1/50 H- coil
IEC Type B 12/620 1/50 H coil
Isthmus (6, 7) 100/20 000 + 8/1600 + H- coil, Hall probe
Isthmus (6, 7) 100/20 000 + 8/1600 + H coil, Hall probe
A773/A773M–01 (2009)
6.2.2 The micrometer or dimensional measuring scales used to determine specimen dimensions for calculation of cross-
sectional area shall be capable of measuring to an accuracy of at least 0.1%.
6.3 Magnetizing Power Source—The power source may range from simple batteries to sophisticated regulated, low-ripple,
protected, programmable types. It shall have sufficient capacity to produce the maximum currents required for magnetization of
the specimen under test.
6.4 Exciting Current Controller—Instantaneousvalueofmagnetizingcurrent,anditsrateofchange,maybecontrolledentirely
manually by
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