ASTM A712-14

Standard Test Method for Electrical Resistivity of Soft Magnetic Alloys

SIGNIFICANCE AND USE
4.1 This test method is suitable for the measurement of the electrical resistivity of specimens of soft magnetic materials.  
4.2 The reproducibility and repeatability of this test method are such that it is suitable for design, specification acceptance, service evaluation, quality assurance, and research and development.
SCOPE
1.1 This test method covers the measurement of electrical resistivity of strip or bar specimens of soft magnetic alloys.  
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this 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.

General Information

• Status: Historical
• Publication Date: 30-Apr-2014
• ICS: 29.030 - Magnetic materials
• Technical Committee: A06 - Magnetic Properties
• Drafting Committee: A06.01 - Test Methods

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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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: A712 − 14
Standard Test Method for
1
Electrical Resistivity of Soft Magnetic Alloys
This standard is issued under the fixed designation A712; 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 5. Apparatus
1.1 This test method covers the measurement of electrical 5.1 Kelvin-type resistance bridge or a digital ohmmeter
resistivity of strip or bar specimens of soft magnetic alloys. (Note 1) or a dc potentiometer and dc ammeter providing
resistance measurements to an accuracy within 0.5 % of the
1.2 The values stated in SI units are to be regarded as
accepted true value.
standard. No other units of measurement are included in this
standard.
NOTE 1—A digital multimeter with a four-wire resistance measuring
capability can be substituted for a digital ohmmeter.
1.3 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
6. Sampling
responsibility of the user of this standard to establish appro-
6.1 Samples shall be representative of the material in the
priate safety and health practices and determine the applica-
physical condition as shipped or agreed upon by the producer
bility of regulatory limitations prior to use.
and the user.
2. Referenced Documents
2
7. Test Specimen
2.1 ASTM Standards:
A34/A34MPractice for Sampling and Procurement Testing
7.1 The test specimen shall be a straight strip or bar or wire
of Magnetic Materials
of substantially uniform cross-sectional area.
7.2 It shall have a minimum length of 0.25 m.
3. Summary of Test Method
7.2.1 Bars and wires having circular, rectangular, or other
3.1 The electrical resistance of a 0.25-m long (minimum)
sections shall be used in the sectional dimensions as produced,
test specimen is measured with a Kelvin-type resistance bridge
unless they are so large as to require cutting a representative
or a digital ohmmeter or the potentiometer-ammeter method.
sample of suitable dimensions.
The resistivity is then calculated from the resistance measure-
7.3 It shall be free of obvious surface defects.
ment and the dimensions of the specimen and is known as the
electrical resistivity of the material. This value is equal to the
7.4 The surface shall be cleaned by wiping with a cloth. Oil
resistancebetweenoppositefacesofacubeofunitdimensions.
and grease, if present on the surface, shall be removed with a
suitablesolvent.Normalsurfaceoxideorcoreplating need not
4. Significance and Use
be removed except in areas in which it is necessary to make
satisfactory electrical contact.
4.1 This test method is suitable for the measurement of the
electrical resistivity of specimens of soft magnetic materials.
8. Procedure
4.2 The reproducibility and repeatability of this test method
are such that it is suitable for design, specification acceptance, 8.1 Measure the electrical resistance of the test specimen
using a Kelvin-type resistance bridge or a digital ohmmeter or
service evaluation, quality assurance, and research and devel-
opment. potentiometer-ammeter system having separate current and
potential leads.
8.2 For strip specimens, measure the length of the test
1
This test method is under the jurisdiction of ASTM Committee A06 on
specimen to within 60.1% and weigh the specimen using a
MagneticPropertiesandisthedirectresponsibilityofSubcommitteeA06.01onTest
Methods.
balance or scale capable of determining the mass within
Current edition approved May 1, 2014. Published May 2014. Originally
60.1%. Determine the average cross-sectional area using Eq
approvedin1975.Lastpreviouseditionapprovedin2013asA712–07(2013).DOI:
1.
10.1520/A0712-14.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
8.3 Forbarorwirespecimens,determinethecross-sectional
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
area by direct measurement using calipers or micrometers
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. capable of measuring within 60.1%.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

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A712 − 14
3
8.4 Thedistancebetweeneachpotentialleadcontactandthe
δ = density of test specimen, kg/m , determined in accor-
corresponding current lead contact shall be at least twice the
dance with Practice A34/A34M.
widthofthetestspecimenwiththetwopotentialcontactslying
9.1.2 Eq 1 assumes a negligible mass of any coating
between the current contacts. The distance between the poten-
material.
tial contacts shall b
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM 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: A712 − 07 (Reapproved 2013) A712 − 14
Standard Test Method for
1
Electrical Resistivity of Soft Magnetic Alloys
This standard is issued under the fixed designation A712; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This test method covers the measurement of electrical resistivity of strip or bar specimens of soft magnetic alloys.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this 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
2.1 ASTM Standards:
A34/A34M Practice for Sampling and Procurement Testing of Magnetic Materials
3. Summary of Test Method
3.1 The electrical resistance of a 0.25-m long (minimum) test specimen is measured with a Kelvin-type resistance bridge or a
digital multimeterohmmeter or the potentiometer-ammeter method. The resistivity is then calculated from the resistance
measurement and the dimensions of the specimen and is known as the electrical resistivity of the material. This value is equal to
the resistance between opposite faces of a cube of unit dimensions.
4. Significance and Use
4.1 This test method is suitable for the measurement of the electrical resistivity of specimens of soft magnetic materials.
4.2 The reproducibility and repeatability of this test method are such that it is suitable for design, specification acceptance,
service evaluation, quality assurance, and research and development.
5. Apparatus
5.1 Kelvin-type resistance bridge or a digital multimeter ohmmeter (Note 1) or a dc potentiometer and dc ammeter providing
resistance measurements to an accuracy within 0.5 % of the accepted true value.
NOTE 1—A digital multimeter with a four-wire resistance measuring capability can be substituted for a digital ohmmeter.
6. Sampling
6.1 Samples shall be representative of the material in the physical condition as shipped or agreed upon by the producer and the
user.
7. Test Specimen
7.1 The test specimen shall be a straight strip or bar or wire of substantially uniform cross-sectional area.
7.2 It shall have a minimum length of 0.25 m. Strip specimens preferably should have a uniform width of 0.03 m minimum,
unless not available.
7.2.1 If width of the strip material to be sampled prevents obtaining a sample of 0.03-m minimum width, the specimen width
to be used shall be the maximum obtainable and shall be agreed upon between the producer and the user.
1
This test method is under the jurisdiction of ASTM Committee A06 on Magnetic Properties and is the direct responsibility of Subcommittee A06.01 on Test Methods.
Current edition approved May 1, 2013May 1, 2014. Published July 2013May 2014. Originally approved in 1975. Last previous edition approved in 20072013 as A712–07.
–07 (2013). DOI: 10.1520/A0712-07R13.10.1520/A0712-14.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
A712 − 14
7.2.1 Bars and wires having circular, rectangular, or other sections shall be used in the sectional dimensions as produced, unless
they are so large as to require cutting a representative sample of suitable dimensions.
7.3 It shall be free of obvious surface defects.
7.4 The surface shall be cleaned by wiping with a cloth. Oil and grease, if present on the surface, shall be removed with a
suitable solvent. Normal surface oxide or core plating need not be removed except in areas in which it is necessary to make
satisfactory electrical contact.
8. Procedure
8.1 Measure the electrical resistance of the test specimen using a Kelvin-type resistance bridge or a digital multimeterohmmeter
or potentiometer-ammeter system having separate current and potential leads.
8.2 For strip specimens, measure the l
...