ASTM E1004-23

Standard Test Method for Determining Electrical Conductivity Using the Electromagnetic (Eddy Current) Method

SIGNIFICANCE AND USE
4.1 Absolute probe coil methods, when used in conjunction with reference standards of known value, provide a means for determining the electrical conductivity of nonmagnetic materials.  
4.2 Electrical conductivity of a specimen, when used in conjunction with another method listed and compared to reference charts, can be used as a means of determining: (1) type of metal or alloy, (2) type of heat treatment (for aluminum this evaluation should be used in conjunction with a hardness examination), (3) aging of the alloy, (4) effects of corrosion, (5) heat damage, (6) temper, and (7) hardness.
SCOPE
1.1 This test method covers a procedure for determining the electrical conductivity of nonmagnetic materials, typically nonmagnetic metals, using the electromagnetic (eddy current) method. The procedure has been written primarily for use with commercially available direct reading electrical conductivity instruments. General purpose eddy current instruments may also be used for electrical conductivity measurements but will not be addressed in this test method.  
1.2 This test method is applicable to nonmagnetic materials that have either a flat or slightly curved surface and includes metals with or without a thin nonconductive coating.  
1.3 Eddy current determinations of electrical conductivity may be used in the sorting of nonmagnetic materials with respect to variables such as type of alloy, aging, cold deformation, heat treatment, effects associated with non-uniform heating or overheating, and effects of corrosion. The usefulness of the examinations of these properties is dependent on the amount of electrical conductivity change caused by a change in the specific variable.  
1.4 Electrical conductivity, when evaluated with eddy current instruments, is usually expressed as a percentage of the conductivity of the International Annealed Copper Standard (% IACS) or Siemens/meter (S/m). The conductivity of the Annealed Copper Standard is defined to be 0.58 × 108 S/m (100 % IACS) at 20 °C.  
1.5 The values stated in SI units are regarded as standard.  
1.6 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 30-Nov-2023
• ICS: 17.220.20 - Measurement of electrical and magnetic quantities
• Technical Committee: E07 - Nondestructive Testing
• Drafting Committee: E07.07 - Electromagnetic Method

Relations

• Replaces: ASTM E1004-17 - Standard Test Method for Determining Electrical Conductivity Using the Electromagnetic (Eddy Current) Method
• Effective Date: 01-Dec-2023
• Refers: ASTM E1316-24 - Standard Terminology for <?Pub Dtl?>Nondestructive Examinations
• Effective Date: 01-Feb-2024
• Refers: ASTM E1316-23b - Standard Terminology for Nondestructive Examinations
• Effective Date: 01-Sep-2023
• Referred By: ASTM B700-20 - Standard Specification for Electrodeposited Coatings of Silver for Engineering Use
• Effective Date: 01-Dec-2023
• Referred By: ASTM B221M-21 - Standard Specification for Aluminum and Aluminum-Alloy Extruded Bars, Rods, Wire, Profiles, and Tubes (Metric)
• Effective Date: 01-Dec-2023
• Referred By: ASTM E3166-20e1 - Standard Guide for Nondestructive Examination of Metal Additively Manufactured Aerospace Parts After Build
• Effective Date: 01-Dec-2023
• Referred By: ASTM B209/B209M-21a - Standard Specification for Aluminum and Aluminum-Alloy Sheet and Plate
• Effective Date: 01-Dec-2023
• Referred By: ASTM B870-21 - Standard Specification for Copper-Beryllium Alloy Forgings and Extrusions (UNS Nos. C17500, C17510, and C17540)
• Effective Date: 01-Dec-2023
• Referred By: ASTM B316/B316M-20 - Standard Specification for Aluminum and Aluminum-Alloy Rivet and Cold-Heading Wire and Rods
• Effective Date: 01-Dec-2023
• Referred By: ASTM B768-22 - Standard Specification for Copper-Cobalt-Beryllium Alloy and Copper-Nickel-Beryllium Alloy Strip and Sheet
• Effective Date: 01-Dec-2023
• Referred By: ASTM E2338-22 - Standard Practice for Characterization of Coatings Using Conformable Eddy Current Sensors without Coating Reference Standards
• Effective Date: 01-Dec-2023
• Referred By: ASTM B247M-20 - Standard Specification for Aluminum and Aluminum-Alloy Die Forgings, Hand Forgings, and Rolled Ring Forgings (Metric)
• Effective Date: 01-Dec-2023
• Referred By: ASTM B248-22 - Standard Specification for General Requirements for Wrought Copper and Copper-Alloy Plate, Sheet, Strip, and Rolled Bar
• Effective Date: 01-Dec-2023
• Referred By: ASTM E543-21 - Standard Specification for Agencies Performing Nondestructive Testing
• Effective Date: 01-Dec-2023
• Referred By: ASTM B49-20 - Standard Specification for Copper Rod for Electrical Purposes
• Effective Date: 01-Dec-2023

Overview

ASTM E1004-23 is the Standard Test Method for Determining Electrical Conductivity Using the Electromagnetic (Eddy Current) Method, published by ASTM International. This widely recognized standard focuses on a precise, nondestructive procedure to measure the electrical conductivity of nonmagnetic metals and materials using eddy current technology. The method is primarily designed for direct reading electrical conductivity instruments, supporting applications that demand accurate characterization and sorting of nonmagnetic materials.

Electrical conductivity measurement via the eddy current method is significant for industries requiring material verification, quality control, and assessment of material properties such as alloy type, heat treatment, corrosion effects, and more. ASTM E1004-23 specifies operating conditions, instrument requirements, and influencing variables to ensure reliable and repeatable results.

Key Topics

• Scope of Application:

  • Suitable for nonmagnetic materials and metals, including those with flat or slightly curved surfaces and with or without a thin nonconductive coating.
  • Not addressed: materials that are magnetic or have substantial nonconductive overlays.

• Measurement Units:

  • Electrical conductivity measurements are typically reported as a percentage of the International Annealed Copper Standard (% IACS) or in Siemens/meter (S/m).

• Significance and Use:

  • Verification and sorting of metals and alloys.
  • Assessment of heat treatment, alloy aging, cold deformation, and corrosion effects based on changes in electrical conductivity.
  • Used as an indicator of material properties such as temper and hardness, notably when used with other test methods (e.g., hardness testing for aluminum).

• Factors Influencing Accuracy:

  • Temperature stabilization of instruments, samples, and reference standards.
  • Proper coupling of probe coil to the specimen, avoiding excessive lift-off or inconsistent surface contact.
  • Material uniformity, surface finish, and specimen thickness.
  • Use, calibration, and care of reference standards.

• Calibration and Standardization:

  • Regular calibration of instruments, with frequent standardization checks using operational reference standards.
  • Reference standards classified as primary, secondary, or operational, each with specific usage protocols for traceability and accuracy.
  • Documentation of test conditions and procedural variables for reproducibility.

Applications

Adoption of ASTM E1004-23 provides practical solutions for:

• Material Identification:
  • Rapid, nondestructive sorting of metals and alloys during production or maintenance.
• Quality Control:
  • Verification of heat treatment cycles, detection of material aging, overdrying, or heat damage.
• Corrosion Assessment:
  • Detecting and quantifying degradation or corrosion effects in nonmagnetic metals.
• Field Testing and Inspection:
  • Suitable for in-service inspections in aerospace, automotive, marine, and electrical industries.
• Certification and Traceability:
  • Supporting compliance and traceability in production through standardized reporting and calibration protocols.

Related Standards

Professionals applying ASTM E1004-23 may also reference the following standards for comprehensive nondestructive testing and material evaluation:

• ASTM B193: Test Method for Resistivity of Electrical Conductor Materials
• ASTM E10/E18: Methods for Brinell and Rockwell Hardness of Metallic Materials
• ASTM E1251: Analysis of Aluminum and Aluminum Alloys by Spark Atomic Emission Spectrometry
• ASTM E543: Specification for Agencies Performing Nondestructive Testing
• ISO 9712: Non-destructive Testing - Qualification and Certification of NDT Personnel
• ASNT SNT-TC-1A and ANSI/ASNT-CP-189: Qualification and Certification of NDT Personnel

These related standards further support robust material characterization and personnel qualification within nondestructive testing programs.

Keywords: ASTM E1004-23, electrical conductivity, eddy current method, nondestructive testing, nonmagnetic metals, % IACS, material identification, quality control, reference standards, instrument calibration

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: E1004 − 23
Standard Test Method for
Determining Electrical Conductivity Using the
Electromagnetic (Eddy Current) Method
This standard is issued under the fixed designation E1004; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope* 1.7 This international standard was developed in accor-
dance with internationally recognized principles on standard-
1.1 This test method covers a procedure for determining the
ization established in the Decision on Principles for the
electrical conductivity of nonmagnetic materials, typically
Development of International Standards, Guides and Recom-
nonmagnetic metals, using the electromagnetic (eddy current)
mendations issued by the World Trade Organization Technical
method. The procedure has been written primarily for use with
Barriers to Trade (TBT) Committee.
commercially available direct reading electrical conductivity
instruments. General purpose eddy current instruments may
2. Referenced Documents
also be used for electrical conductivity measurements but will
2.1 ASTM Standards:
not be addressed in this test method.
B193 Test Method for Resistivity of Electrical Conductor
1.2 This test method is applicable to nonmagnetic materials
Materials
that have either a flat or slightly curved surface and includes
E10 Test Method for Brinell Hardness of Metallic Materials
metals with or without a thin nonconductive coating.
E18 Test Methods for Rockwell Hardness of Metallic Ma-
1.3 Eddy current determinations of electrical conductivity terials
E105 Guide for Probability Sampling of Materials
may be used in the sorting of nonmagnetic materials with
respect to variables such as type of alloy, aging, cold E122 Practice for Calculating Sample Size to Estimate, With
Specified Precision, the Average for a Characteristic of a
deformation, heat treatment, effects associated with non-
uniform heating or overheating, and effects of corrosion. The Lot or Process
E140 Hardness Conversion Tables for Metals Relationship
usefulness of the examinations of these properties is dependent
on the amount of electrical conductivity change caused by a Among Brinell Hardness, Vickers Hardness, Rockwell
Hardness, Superficial Hardness, Knoop Hardness, Sclero-
change in the specific variable.
scope Hardness, and Leeb Hardness
1.4 Electrical conductivity, when evaluated with eddy cur-
E543 Specification for Agencies Performing Nondestructive
rent instruments, is usually expressed as a percentage of the
Testing
conductivity of the International Annealed Copper Standard
E1251 Test Method for Analysis of Aluminum and Alumi-
(% IACS) or Siemens/meter (S/m). The conductivity of the
num Alloys by Spark Atomic Emission Spectrometry
Annealed Copper Standard is defined to be 0.58 × 10 S/m
E1316 Terminology for Nondestructive Examinations
(100 % IACS) at 20 °C.
E2371 Test Method for Analysis of Titanium and Titanium
1.5 The values stated in SI units are regarded as standard.
Alloys by Direct Current Plasma and Inductively Coupled
Plasma Atomic Emission Spectrometry (Performance-
1.6 This standard does not purport to address all of the
Based Test Methodology)
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
3. Terminology
priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use. 3.1 Definitions—Definitions of terms relating to eddy cur-
rent examination are given in Terminology E1316.
3.2 Definitions of Terms Specific to This Standard:
This test method is under the jurisdiction of ASTM Committee E07 on
Nondestructive Testing and is the direct responsibility of Subcommittee E07.07 on
Electromagnetic Method. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Dec. 1, 2023. Published February 2024. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 1991. Last previous edition approved in 2017 as E1004 – 17. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/E1004-23. the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E1004 − 23
3.2.1 temperature coeffıcient, n—the fractional or percent- and practical proficiency tests, that they possess the skills and
age change in electrical conductivity per degree Celsius change job knowledge necessary to ensure acceptable workmanship.
in temperature.
6.2 Qualification of Nondestructive Testing Agencies—If
specified in the contractual agreement, NDT agencies shall be
4. Significance and Use
qualified and evaluated as described in Practice E543. The
4.1 Absolute probe coil methods, when used in conjunction applicable edition of Practice E543 shall be specified in the
with reference standards of known value, provide a means for contractual agreement.
determining the electrical conductivity of nonmagnetic mate-
6.3 The following additional items are subject to contractual
rials.
agreement between the parties using or referencing this test
4.2 Electrical conductivity of a specimen, when used in
method.
conjunction with another method listed and compared to
6.3.1 Timing of Examination.
reference charts, can be used as a means of determining:
6.3.2 Extent of Examination.
(1) type of metal or alloy, (2) type of heat treatment (for
6.3.3 Reporting Criteria/Acceptance Criteria.
aluminum this evaluation should be used in conjunction with a
6.3.4 Reexamination of Repaired/Reworked Items.
hardness examination), (3) aging of the alloy, (4) effects of
corrosion, (5) heat damage, (6) temper, and (7) hardness.
7. Variables Influencing Accuracy
7.1 Consider the influence of the following variables to
5. Limitations
ensure an accurate evaluation of electrical conductivity.
5.1 The ability to accomplish the examinations included in
7.1.1 Temperature—The instrument, probe, reference
4.2 is dependent on the conductivity change caused by the
standards, and parts being examined shall be stabilized at
variable of interest. If the conductivity is a strong function of
ambient temperature prior to conductivity evaluation. When
the variable of interest, these examinations can be very
possible, examinations should be performed at room tempera-
accurate. In some cases, however, changes in conductivity due
ture (typically 20 °C).
to changes in the variable of interest may be too small to detect.
7.1.2 Probe Coil to Specimen Coupling—Variations in the
The ability to isolate the variable of interest from other
separation between the probe coil and the surface of the
variables is also important. For example, if the alloy is not
specimen (lift-off) can cause large changes in the instrument
known, the heat treatment cannot be determined from conduc-
output signal. Instruments vary widely in sensitivity due to
tivity alone.
lift-off, and some have adjustments for minimizing it. Stan-
5.2 If electrical conductivity measurements are used to
dardize the instrument with values at least as large as the
interpret a property that is related to the electrical conductivity,
known lift-off. Surface curvature may also affect the coupling.
the correlation curve relating the property to the electrical
(Consult the manufacturer’s manual for limitations on lift-off
conductivity should be established for such use. For example,
and surface curvature).
knowing alloy, conductivity, and hardness; or the conductivity,
7.1.3 Edge Effect—Consult manufacturer’s instructions to
chemistry, and thermal history; or conductivity, chemistry, and
determine equipment limitations for inspection adjacent to any
tensile strength, the adequacy of the heat treatment can be
discontinuity. If no information regarding probe use restric-
estimated.
tions or limitations adjacent to such discontinuities exist,
examinations should not be performed within two coil diam-
6. Basis of Application
eters of any discontinuity.
6.1 Personnel Qualification: 7.1.4 Uniformity of Specimen—Variations in material prop-
6.1.1 If specified by the contractual agreement, personnel erties are common and can be quite large. Discontinuities or
performing examinations to this test method shall be qualified inhomogeneities in the nonmagnetic material being examined
in accordance with a nationally or internationally recognized near the position of the probe coil will change the value of the
NDT personnel qualification practice or standard and certified
measured conductivity.
by the employer or certifying agency, as applicable. The
NOTE 1—Similar materials from various manufacturing methods
practice of the standard used and its applicable revision shall be
(extrusion, forging, casting, rolling, machined vs. unmachined) may
specified in the contractual agreement between the using
exhibit significant conductivity variation between processes. Eddy current
parties. conductivity meters can be affected by detecting differences in material
grain structure, alloy uniformity, and internal stresses so care must be
6.1.2 Qualification and certification for personnel may be
taken as this can influence accuracy.
reduced when the following conditions are met:
6.1.2.1 The examination will be limited to operating 7.1.5 Surface Conditions—Surface treatments and rough-
equipment, which displays the results in percent IACS or other ness can affect the measured conductivity value of a material.
direct read values. Conductive coatings such as cladding will have a pronounced
6.1.2.2 A specific procedure is used that is approved by a effect on conductivity readings as compared to the base
certified Level III in accordance with 6.1.1. material (uncoated or unclad) values. Procedures for determin-
6.1.2.3 Documentation of training and examination is per- ing the electrical conductivity of clad materials are not ad-
formed to ensure that personnel are qualified. Qualified per- dressed in this test method. The specimen surface should be
sonnel are those who have demonstrated, by passing written clean and free of grease.
E1004 − 23
7.1.6 Instrument Stability—Instrument drift, noise, and non- These formulas are for nonmagnetic materials when the
linearities can cause inaccuracies in the measurement. relative permeability, μ =1. The change in the standard depth of
r
penetration due to coil diameter variation is not considered in
7.1.7 Nonunique Conductivity Values—It should be noted
the above equation.
that two different alloys can have the same conductivity. Thus,
7.1.8.2 When testing thin specimen materials, stacking of
in some cases, a measurement of conductivity may not
the specimen materials may be acceptable. Similar material,
uniquely characterize an alloy. Overheated parts and some
preferably from the same lot, batch, or sheet, may be used to
heat-treated aluminum alloys are examples of materials that
back the specimen material being interrogated, thereby increas-
may have identical conductivity values for different heat
ing the effective thickness. Stacked materials must be bare,
treatments or tempers. It is recommended, if chemistry and
without coatings or cladding, and fit so that they are in intimate
thermal history are unknown, that an indentation hardness test
contact at the area to be measured. The total thickness of the
(such as Rockwell, Vickers, Brinell), accompanied by a test to
stacked material must be at least 2.6 standard depths of
determine chemistry such as Laser-Induced Breakdown Spec-
penetration.
troscopy (LIBS), X-Ray Fluorescence (XRF), Atomic Emis-
7.1.9 Reference Standard Conductivity—Electrical conduc-
sion Spectrometry (AES), Inductively Coupled Plasma (ICP),
tivity reference standards are precise electrical standards and
or Glow Discharge Mass Spectrometry (GDMS) chemical spot
should be treated as such. Scratching of the surface of the
test or other laboratory analysis be used to identify an unknown
standard may introduce measurement error. Avoid dropping or
material. Refer to Test Methods E10, E18, E1251, and E2371,
other rough handling of the standard. Keep the surface of the
and Conversion Tables E140, for more information on methods standard as clean as possible. Clean with a nonreactive liquid
for determining chemistry. and a soft cloth or tissue. Store reference standards in a place
where the temperature is relatively constant. Avoid thermal
7.1.8 Specimen Thickness—The specimen thickness can
shocking of the reference standards or placing them where
affect the electrical conductivity measurement. Eddy current
large temperature variations are present.
density decreases exponentially with depth (that is, distance
from the conducting material surface). The depth at which the
8. Apparatus
density is approximately 37 % (1/e) of its value at the surface
is called the standard depth of penetration δ. If the thickness of 8.1 Instrument—The instrument (electronic apparatus) shall
be capable of energizing the probe coil with alternating
the specimen and the reference standards is at least 2.6δ, the
currents of suitable frequencies and power levels and shall be
effect of thickness is negligible. Smaller depths of penetration
capable of sensing changes in the measured impedance of the
(higher frequencies) may be desirable for measuring surface
coil. Equipment may include any suitable signal-processing
effects. The eddy current density decrease with depth is also
device (phase discriminator, filter circuits, and so forth). The
affected by the coil diameter. Consult the instrument manufac-
output may be displayed in either analog or digital readouts.
turer if penetration depth appears to be a source of error in the
Readout is normally in percent IACS although it may be scaled
measurement.
for readings in other un
...

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: E1004 − 17 E1004 − 23
Standard Test Method for
Determining Electrical Conductivity Using the
Electromagnetic (Eddy Current) Method
This standard is issued under the fixed designation E1004; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope*
1.1 This test method covers a procedure for determining the electrical conductivity of nonmagnetic metals materials, typically
nonmagnetic metals, using the electromagnetic (eddy current) method. The procedure has been written primarily for use with
commercially available direct reading electrical conductivity instruments. General purpose eddy current instruments may also be
used for electrical conductivity measurements but will not be addressed in this test method.
1.2 This test method is applicable to metals nonmagnetic materials that have either a flat or slightly curved surface and includes
metals with or without a thin nonconductive coating.
1.3 Eddy current determinations of electrical conductivity may be used in the sorting of metals nonmagnetic materials with respect
to variables such as type of alloy, aging, cold deformation, heat treatment, effects associated with non-uniform heating or
overheating, and effects of corrosion. The usefulness of the examinations of these properties is dependent on the amount of
electrical conductivity change caused by a change in the specific variable.
1.4 Electrical conductivity, when evaluated with eddy current instruments, is usually expressed as a percentage of the conductivity
of the International Annealed Copper Standard (% IACS) or Siemens/meter (S/m). The conductivity of the Annealed Copper
Standard is defined to be 0.58 × 10 S/m (100 % IACS) at 20°C.20 °C.
1.5 The values stated in SI units are regarded as standard.
1.6 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 healthsafety, health, and environmental practices and determine
the applicability of regulatory limitations prior to use.
1.7 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
This test method is under the jurisdiction of ASTM Committee E07 on Nondestructive Testing and is the direct responsibility of Subcommittee E07.07 on Electromagnetic
Method.
Current edition approved June 1, 2017Dec. 1, 2023. Published June 2017February 2024. Originally approved in 1991. Last previous edition approved in 20092017 as
E1004 - 09.E1004 – 17. DOI: 10.1520/E1004-17.10.1520/E1004-23.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E1004 − 23
2. Referenced Documents
2.1 ASTM Standards:
B193 Test Method for Resistivity of Electrical Conductor Materials
E10 Test Method for Brinell Hardness of Metallic Materials
E18 Test Methods for Rockwell Hardness of Metallic Materials
E105 Guide for Probability Sampling of Materials
E122 Practice for Calculating Sample Size to Estimate, With Specified Precision, the Average for a Characteristic of a Lot or
Process
E140 Hardness Conversion Tables for Metals Relationship Among Brinell Hardness, Vickers Hardness, Rockwell Hardness,
Superficial Hardness, Knoop Hardness, Scleroscope Hardness, and Leeb Hardness
E543 Specification for Agencies Performing Nondestructive Testing
E1251 Test Method for Analysis of Aluminum and Aluminum Alloys by Spark Atomic Emission Spectrometry
E1316 Terminology for Nondestructive Examinations
E2371 Test Method for Analysis of Titanium and Titanium Alloys by Direct Current Plasma and Inductively Coupled Plasma
Atomic Emission Spectrometry (Performance-Based Test Methodology)
2.2 ASNT Documents:
SNT-TC-1A Recommended Practice for Personnel Qualification and Certification In Nondestructive Testing
ANSI/ASNT-CP-189 Standard for Qualification and Certification of Nondestructive Testing Personnel
2.3 AIA Document:
NAS–410 Certification and Qualification of Nondestructive Testing Personnel
2.4 ISO Standard:
ISO 9712 Non-Destructive Testing: Qualification and Certification of NDT Personnel
3. Terminology
3.1 Definitions—Definitions of terms relating to eddy current examination are given in Terminology E1316.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 temperature coeffıcient—coeffıcient, n—the fractional or percentage change in electrical conductivity per degree Celsius
change in temperature.
4. Significance and Use
4.1 Absolute probe coil methods, when used in conjunction with reference standards of known value, provide a means for
determining the electrical conductivity of nonmagnetic materials.
4.2 Electrical conductivity of a sample,specimen, when used in conjunction with another method listed and compared to reference
charts, can be used as a means of determining: (1) type of metal or alloy, (2) type of heat treatment (for aluminum this evaluation
should be used in conjunction with a hardness examination), (3) aging of the alloy, (4) effects of corrosion, (5) heat damage, (6)
temper, and (7) hardness.
5. Limitations
5.1 The ability to accomplish the examinations included in 4.2 is dependent on the conductivity change caused by the variable
of interest. If the conductivity is a strong function of the variable of interest, these examinations can be very accurate. In some
cases, however, changes in conductivity due to changes in the variable of interest may be too small to detect. The ability to isolate
the variable of interest from other variables is also important. For example, if the alloy is not known, the heat treatment cannot
be determined from conductivity alone.
5.2 If electrical conductivity measurements are used to interpret a property that is related to the electrical conductivity, the
correlation curve relating the property to the electrical conductivity should be established for such use. For example, knowing alloy,
conductivity, and hardness; or the conductivity, chemistry, and thermal history; or conductivity, chemistry, and tensile strength, the
adequacy of the heat treatment can be estimated.
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.
E1004 − 23
6. Basis of Application
6.1 Personnel Qualification:
6.1.1 If specified by the contractual agreement, personnel performing examinations to this test method shall be qualified in
accordance with a nationally or internationally recognized NDT personnel qualification standard such as ANSI/ASNT-CP-189,
SNT-TC-1A, NAS-410, ISO 9712 , or a similar document practice or standard and certified by the employer or certifying agency,
as applicable. The practice of the standard used and its applicable revision shall be specified in the contractual agreement between
the using parties.
NOTE 1—Note that NAS-410 does not require personnel certification when using direct read instruments
6.1.2 Qualification and certification for personnel may be reduced when the following conditions are met:
6.1.2.1 The examination will be limited to operating equipment, which displays the results in percent IACS.IACS or other direct
read values.
6.1.2.2 A specific procedure is used that is approved by a certified Level III in accordance with 6.1.1.
6.1.2.3 Documentation of training and examination is performed to ensure that personnel are qualified. Qualified personnel are
those who have demonstrated, by passing written and practical proficiency tests, that they possess the skills and job knowledge
necessary to ensure acceptable workmanship.
6.2 Qualification of Nondestructive Testing Agencies—If specified in the contractual agreement, NDT agencies shall be qualified
and evaluated as described in Practice E543. The applicable edition of Practice E543 shall be specified in the contractual
agreement.
6.3 The following additional items are subject to contractual agreement between the parties using or referencing this test method.
6.3.1 Timing of ExaminationExamination.
6.3.2 Extent of ExaminationExamination.
6.3.3 Reporting Criteria/Acceptance CriteriaCriteria.
6.3.4 Reexamination of Repaired/Reworked ItemsItems.
7. Variables Influencing Accuracy
7.1 Consider the influence of the following variables to ensure an accurate evaluation of electrical conductivity.
7.1.1 Temperature—The instrument, probe, reference standards, and parts being examined shall be stabilized at ambient
temperature prior to conductivity evaluation. When possible, examinations should be performed at room temperature (typically
20 °C).
7.1.2 Probe Coil to MetalSpecimen Coupling—Variations in the separation between the probe coil and the surface of the
samplespecimen (lift-off) can cause large changes in the instrument output signal. Instruments vary widely in sensitivity due to
lift-off, and some have adjustments for minimizing it. Standardize the instrument with values at least as large as the known lift-off.
Surface curvature may also affect the coupling. (Consult the manufacturer’s manual for limitations on lift-off and surface
curvature).
7.1.3 Edge Effect—Consult manufacturer’s instructions to determine equipment limitations for inspection adjacent to any
discontinuity. If no information regarding probe use restrictions or limitations adjacent to such discontinuities exist, examinations
should not be performed within two coil diameters of any discontinuity.
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7.1.4 Uniformity of Sample—Specimen—Variations in material properties are common and can be quite large. Discontinuities or
inhomogeneities in the metal nonmagnetic material being examined near the position of the probe coil will change the value of
the measured conductivity.
NOTE 1—Similar materials from various manufacturing methods (extrusion, forging, casting, rolling, machined vs. unmachined) may exhibit significant
conductivity variation between processes. Eddy current conductivity meters can be affected by detecting differences in material grain structure, alloy
uniformity, and internal stresses so care must be taken as this can influence accuracy.
7.1.5 Surface Conditions—Surface treatments and roughness can affect the measured conductivity value of a material. Conductive
coatings such as cladding will have a pronounced effect on conductivity readings as compared to the base metal material (uncoated
or unclad) values. Procedures for determining the electrical conductivity of clad materials are not addressed in this test method.
The samplespecimen surface should be clean and free of grease.
7.1.6 Instrument Stability—Instrument drift, noise, and nonlinearities can cause inaccuracies in the measurement.
7.1.7 Nonunique Conductivity Values—It should be noted that two different alloys can have the same conductivity. Thus, in some
cases, a measurement of conductivity may not uniquely characterize an alloy. Overheated parts and some heat-treated aluminum
alloys are examples of materials that may have identical conductivity values for different heat treatments or tempers. It is
recommended, if chemistry and thermal history are unknown, that an indentation hardness test (such as Rockwell, Vickers,
Brinell), accompanied by a test to determine chemistry such as Laser-Induced Breakdown Spectroscopy (LIBS), X-Ray
Fluorescence (XRF), Atomic Emission Spectrometry (AES), Inductively Coupled Plasma (ICP), or Glow Discharge Mass
Spectrometry (GDMS) chemical spot test or other laboratory analysis be used to identify an unknown material. Refer to Test
Methods E10, E18, E1251, and E2371, and Standard Conversion Tables E140, for more information on methods for determining
chemistry.
7.1.8 SampleSpecimen Thickness—Eddy current density decreases exponentially with depth (that is, distance from the metal
surface). The depth at which the density is approximately 37 % (1/e) of its value at the surface is called the standard depth of
penetration δ. Calculate the standard depth of penetration for nonmagnetic materials using one of the following formulas:
503.3
δ5 ~m!, σinS⁄m (1)
=fσ
50.3
δ5 ~mm!, ρin μΩ•cm, μ 5 1 (2)
r
= μ f1/ρ
r
δ5 ~m!,σinS⁄m,μ 5 μ μ , μ 5 4π ×10 H⁄m, μ 5 1 (3)
o r o r
=πμfσ
δ 5 ~mm!,σin%IACS (4)
=fσ
where:
σ = electrical conductivity of the sample,
ρ = electrical resistivity, and
f = examination frequency in Hz.
These formulas are for nonmagnetic materials when the relative permeability, μThe specimen thickness can affect the electrical
conductivity measurement. Eddy current density decreases exponentially with depth (that is, distance from the conducting material
surface). =1. The depth at which the density is approximately 37 % (1/e) of its value at the surface is called the standard depth of
r
penetration δ. If the thickness of the samplespecimen and the reference standards is at least 2.6δ, the effect of thickness is
negligible. Smaller depths of penetration (higher frequencies) may be desirable for measuring surface effects. The eddy current
density decrease with depth is also affected by the coil diameter. The change due to coil diameter variation is not considered in
the above equation. Consult the instrument manufacturer if penetration depth appears to be a source of error in the measurement.
NOTE 3—When testing thin materials, stacking of the test parts may be acceptable. Similar material, preferably from the same batch or sheet, may be used
to back the material being interrogated, thereby increasing the effective thickness. Stacked materials must be bare, without cladding, and fit so that they
are in intimate contact at the area to be measured. The total thickness of the stacked material must be at least 2.6 standard depths of penetration.
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7.1.8.1 If needed to confirm that the specimen thickness is sufficiently large, the standard depth of penetration for nonmagnetic
materials can be calculated using one of the following formulas:
503.3
δ5 m , σinS⁄m (1)
~ !
=fσ
50.3
δ5 ~mm!, ρin μΩ•cm, μ 5 1 (2)
r
= μ f1/ρ
r
δ5 ~m!,σinS⁄m,μ 5 μ μ , μ 5 4π ×10 H⁄m, μ 5 1 (3)
o r o r
=πμfσ
δ 5 mm ,σin%IACS (4)
~ !
=fσ
where:
μ = magnetic permeability of the specimen material,
μ = magnetic permeability of free space (air),
o
μ = relative magnetic permeability of the specimen material,
r
σ = electrical conductivity of the specimen material,
ρ = electrical resistivity of the specimen material, and
f = examination frequency in Hz.
These formulas are for nonmagnetic materials when the relative permeability, μ =1. The change in the standard depth of
r
penetration due to coil diameter variation is not considered in the above equation.
7.1.8.2 When testing thin specimen materials, stacking of the specimen materials may be acceptable. Similar material, preferably
from the same lot, batch, or sheet, may be used to back the specimen material being interrogated, thereby increasing the effective
thickness. Stacked materials must be bare, without coatings or cladding, and fit so that they are in intimate contact at the area to
be measured. The total thickness of the stacked material must be at least 2.6 standard depths of penetration.
7.1.9 Reference Standard Conductivity—Electrical conductivity reference standards are precise electrical standards and should be
treated as such. Scratching of the surface of the standard may introduce measurement error. Avoid dropping or other rough handling
of the standard. Keep the surface of the standard as clean as possible. Clean with a nonreactive liquid and a soft cloth or tissue.
Store reference standards in a place where the t
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