ASTM A341 / A341M - 16

    Standard Test Method for Direct Current Magnetic Properties of Soft Magnetic Materials Using D-C Permeameters and the Point by Point (Ballistic) Test Methods

    Active Standard ASTM A341 / A341M | Developed by Subcommittee: A06.01

    Book of Standards Volume: 03.04

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    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 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 [16 kA/m] is required, permeameters are the only practical means of measuring magnetic properties.

    3.2 This test method is suitable for specification acceptance, service evaluation, research and development and design.

    3.3 When the test specimen is fabricated from a 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.

    1. Scope

    1.1 This test method provides dc permeameter tests for the basic magnetic properties of soft magnetic 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. This method has been historically referred to as the ballistic test method. For testing hard or permanent magnet materials, Test Method A977/A977M shall be used.

    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 magnetic flux density range from essentially zero to the saturation induction for most materials.

    1.5 Recommendations of the useful magnetic field strength range for each of the permeameters are shown in Table 1.2 Permeameters particularly well suited for general testing of soft magnetic materials are shown in boldface. Also, see Sections 3 and 4 for general limitations relative to the use of permeameters.

    (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.
    (D) The boldface numbers in parentheses refer to a list of references at the end of this standard.

    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 magnetic 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 ( ) 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.

    2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.

    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

    A977/A977M Test Method for Magnetic Properties of High-Coercivity Permanent Magnet Materials Using Hysteresigraphs

    IEC Standard

    Publication 60404-4,

    Other Documents

    NIST Circular No. 74, pg. 269 Available from National Institute of Standards and Technology (NIST), 100 Bureau Dr., Stop 1070, Gaithersburg, MD 20899-1070,

    ICS Code

    ICS Number Code 29.030 (Magnetic materials)

    UNSPSC Code

    UNSPSC Code 31381100(Castmagnets and magnet assemblies); 31381200(Sintered magnets and magnet assemblies)

    Referencing This Standard
    Link Here
    Link to Active (This link will always route to the current Active version of the standard.)

    DOI: 10.1520/A0341_A0341M-16

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    Citation Format

    ASTM A341 / A341M-16, Standard Test Method for Direct Current Magnetic Properties of Soft Magnetic Materials Using D-C Permeameters and the Point by Point (Ballistic) Test Methods, ASTM International, West Conshohocken, PA, 2016,

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