ASTM A341/A341M-00(2011)
(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 A596/A596M 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 A34/A34M.
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 A340. Note that the term flux density used in this document is synonymous with the term magnetic induction.
1.7 WarningMercury 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 Reluctance
...
General Information
Relations
Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:A341/A341M–00 (Reapproved 2011)
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.
1. Scope materials.Cautionshouldbetakenwhenhandlingmercuryand
mercury-containing products. See the applicable product Ma-
1.1 This test method provides dc permeameter tests for the
terial Safety Data Sheet (MSDS) for details and EPA’s website
basicmagneticpropertiesofmaterialsintheformofbars,rods,
(http://www.epa.gov/mercury/faq.htm) for additional informa-
wire, or strip specimens which may be cut, machined, or
tion. Users should be aware that selling mercury or mercury-
ground from cast, compacted, sintered, forged, extruded,
containingproducts,orboth,inyourstatemaybeprohibitedby
rolled, or other fabricated materials. It includes tests for
state law.
determination of the normal induction under symmetrically
1.8 The values and equations stated in customary cgs-emu
cyclically magnetized (SCM) conditions and the hysteresis
and inch-pound or SI units are to be regarded separately as
loop (B-H loop) taken under conditions of rapidly changing or
standard. Within this standard, SI units are shown in brackets
steep wavefront reversals of the direct current magnetic field
except for the sections concerning calculations where there are
strength.
separate sections for the respective unit systems. The values
1.2 This test method shall be used in conjunction with
stated in each system may not be exact equivalents; therefore,
Practice A34/A34M.
each system shall be used independently of the other. Combin-
1.3 This test method covers a range of magnetic field
ingvaluesfromthetwosystemsmayresultinnonconformance
strength in the specimen from about 0.05 Oe [4 A/m] up to
with this standard.
above 5000 Oe [400 kA/M] through the use of several
1.9 This standard does not purport to address all of the
permeameters. The separate permeameters cover this test
safety concerns, if any, associated with its use. It is the
region in several overlapping ranges.
responsibility of the user of this standard to establish appro-
1.4 Normal induction and hysteresis properties may be
priate safety and health practices and determine the applica-
determined over the flux density range from essentially zero to
bility of regulatory limitations prior to use.
intrinsic saturation for most materials.
1.5 Recommendations of the useful magnetic field strength
2. Referenced Documents
range for each of the permeameters are shown in Table 1 .
2.1 ASTM Standards:
Also,seeSections3and4forgenerallimitationsrelativetothe
A34/A34M Practice for Sampling and Procurement Testing
use of permeameters.
of Magnetic Materials
1.6 Thesymbolsandabbreviateddefinitionsusedinthistest
A340 Terminology of Symbols and Definitions Relating to
method appear with Fig. 1 and in appropriate sections of this
Magnetic Testing
document. For the official definitions, see Terminology A340.
A596/A596M Test Method for Direct-Current Magnetic
Note that the term flux density used in this document is
Properties of Materials Using the Ballistic Method and
synonymous with the term magnetic induction.
Ring Specimens
1.7 Warning—Mercury has been designated by EPA and
2.2 IEC Standard:
many state agencies as a hazardous material that can cause
Publication 60404-4, Ed. 2.0 Magnetic Materials – Part 4:
central nervous system, kidney, and liver damage. Mercury, or
Methods of Measurement of D.C. Magnetic Properties of
its vapor, may be hazardous to health and corrosive to
Iron and Steel, IEC, 1995
This test method is under the jurisdiction of ASTM Committee A06 on
MagneticPropertiesandisthedirectresponsibilityofSubcommitteeA06.01onTest
Methods. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Oct. 1, 2011. Published October 2011. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1969. Last previous edition approved in 2005 as A341/ Standards volume information, refer to the standard’s Document Summary page on
´1
A341M–00(2005) . DOI: 10.1520/A0341_A0341M-00R11. the ASTM website.
2 4
The boldface numbers in parentheses refer to a list of references at the end of Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
this standard. 4th Floor, New York, NY 10036.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
A341/A341M–00 (2011)
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.
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
the suitability of the material for the intended application.
4. Interferences
NOTE 1—
4.1 In general, permeameters do not maintain a uniform
A —Multirange ammeter (main current)
magneticfieldineithertheaxialorradialdirectionsaroundthe
A —Multirange ammeter (hysteresis current)
test specimen. The field gradients in both of these directions
B—Flux density test position for Switch S
willdifferinthevariouspermeameters.AlsotheH-sensingand
F—Electronic Integrator
H—Magnetic field strength test position for Switch S
B-sensing coils of the different permeameters are not identical
N —Magnetizing coil
1 in area, in turns, or in length or identically located. Although
N —Flux sensing (B) coil
test specimens are prepared to have uniform physical cross
N —Magnetic field strength sensing coil
section, they may have undetected nonuniform magnetic prop-
R —Main current control rheostat
erties radially or axially along the specimen length adjacent to
R —Hysteresis current control rheostat
the H or B coils. Some permeameters may also introduce
S —Reversing switch for magnetizing current
S —Shunting switch for hysteresis current control rheostat clamping strains into the test specimen. For the above reasons
S —Integrator selector switch
test results obtained on a test specimen with one type per-
SP—Specimen
meameter may not agree closely with those obtained on the
FIG. 1 Basic Circuit Using Permeameter
same test specimen using another type of permeameter.
5. Apparatus
2.3 Other Documents:
5.1 Because of the differences in physical construction of
NIST Circular No. 74, pg. 269
the various permeameters listed in Table 1, no standard list of
NIST Scientific Paper 117, SPBTA
components is given. When used with a particular type of
permeameter, the components should conform to the general
3. Significance and Use
requirementslistedbelow.Abasicschematicofapermeameter
3.1 Permeameters require the use of yokes to complete the
is shown in Fig. 1.
magnetic circuit and are therefore inherently less accurate than
5.2 Permeameter—The particular permeameter used shall
ring test methods. Refer to Test Method A596/A596M for
be of high quality construction. The yokes should be made of
further details on ring test methods. However, when testing
high permeability alloy such as oriented or nonoriented silicon
certainshapesasbarsorwhenmagneticfieldstrengthinexcess
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
Available from National Institute of Standards and Technology (NIST), 100
Bureau Dr., Stop 1070, Gaithersburg, MD 20899-1070, http://www.nist.gov. fromthesedimensionsshouldbesuchthattheyolkisoperating
A341/A341M–00 (2011)
TABLE 2 Number of Test Strips
at or below the point of maximum permeability for the highest
test flux densities encountered. Yoke construction may consist Nominal Thickness Gage Number of
in. mm Number Strips
of either stacked laminations or stripwound C cores suitably
0.0100 to 0.0250 0.254 to 0.635 32 to 24, incl 12
bolted or adhesive bonded together.
0.0280 to 0.0435 0.711 to 1.105 23 to 19, incl 8
0.0500 and over 1.27 and over 18 and thicker 4
5.3 Power Supply—The magnetizing current shall be sup-
plied by either storage batteries or dc power supplies. Bipolar
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-
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 evaluated in one
stability, and ease of operation, electronic charge integrators direction, it shall conform to this table or to the requirements
are the preferred means of measuring magnetic flux. Integra- for best test qualit
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.