1、Designation: E 1004 09Standard Test Method forDetermining Electrical Conductivity Using theElectromagnetic (Eddy-Current) Method1This standard is issued under the fixed designation E 1004; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revi
2、sion, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript 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*1.1 This test method c
3、overs a procedure for determining theelectrical conductivity of nonmagnetic metals using the elec-tromagnetic (eddy-current) method. The procedure has beenwritten primarily for use with commercially available directreading electrical conductivity instruments. General purposeeddy-current instruments
4、may also be used for electricalconductivity measurements but will not be addressed in thistest method.1.2 This test method is applicable to metals that have eithera flat or slightly curved surface and includes metals with orwithout a thin nonconductive coating.1.3 Eddy-current determinations of elec
5、trical conductivitymay be used in the sorting of metals with respect to variablessuch 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 ofthese properties is dependent on t
6、he amount of electricalconductivity change caused by a change in the specificvariable.1.4 Electrical conductivity, when evaluated with eddy-current instruments, is usually expressed as a percentage of theconductivity of the International Annealed Copper Standard(IACS). The conductivity of the Anneal
7、ed Copper Standard isdefined to be 0.58 3 108S/m (100 % IACS) at 20C.1.5 The values stated in SI units are regarded as standard.1.6 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish
8、appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2B 193 Test Method for Resistivity of Electrical ConductorMaterialsE 105 Practice for Probability Sampling Of MaterialsE 122 Practice for Calcula
9、ting Sample Size to Estimate,With Specified Precision, the Average for a Characteristicof a Lot or ProcessE 543 Specification for Agencies Performing Nondestruc-tive TestingE 1316 Terminology for Nondestructive Examinations2.2 ASNT Documents:Recommended Practice SNT-TC-1A for Personnel Qualifi-catio
10、n and Certification In Nondestructive Testing3ANSI/ASNT-CP-189 Standard for Qualification and Certi-fication of NDT Personnel32.3 AIA Document:NAS410 Certification and Qualification of NondestructiveTesting Personnel43. Terminology3.1 DefinitionsDefinitions of terms relating to eddy-current examinat
11、ion are given in Terminology E 1316.3.2 Definitions of Terms Specific to This Standard:1This test method is under the jurisdiction of ASTM Committee E07 onNondestructive Testing and is the direct responsibility of Subcommittee E07.07 onElectromagnetic Method.Current edition approved May 15, 2009. Pu
12、blished June 2009. Originallyapproved in 1991. Last previous edition approved in 2002 as E 1004 - 02.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards D
13、ocument Summary page onthe ASTM website.3Available fromAmerican Society for Nondestructive Testing (ASNT), P.O. Box28518, 1711 Arlingate Ln., Columbus, OH 43228-0518, http:/www.asnt.org.4Available from Aerospace Industries Association of America, Inc. (AIA), 1000Wilson Blvd., Suite 1700,Arlington, V
14、A22209-3928, http:/www.aia-aerospace.org.1*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.3.2.1 temperature coeffcientthe fractional or percentagechange in electrical c
15、onductivity per degree Celsius change intemperature.4. Significance and Use4.1 Absolute probe coil methods, when used in conjunctionwith reference standards of known value, provide a means fordetermining the electrical conductivity of nonmagnetic mate-rials.4.2 Electrical conductivity of a sample ca
16、n be used as ameans of determining: (1) type of metal or alloy, (2) type ofheat treatment (for aluminum this evaluation should be used inconjunction with a hardness examination), (3) aging of thealloy, (4) effects of corrosion, and (5) heat damage.5. Limitations5.1 The ability to accomplish the exam
17、inations included in4.2 is dependent on the conductivity change caused by thevariable of interest. If the conductivity is a strong function ofthe variable of interest, these examinations can be veryaccurate. In some cases, however, changes in conductivity dueto changes in the variable of interest ma
18、y be too small to detect.The ability to isolate the variable of interest from othervariables is also important. For example, if the alloy is notknown, the heat treatment cannot be determined from conduc-tivity alone.5.2 The curve relating temper and conductivity of an alu-minum alloy should be known
19、 before attempting to interpretconductivity measurements. For example, knowing alloy andheat treatment, the adequacy of the heat treatment can beestimated.6. Basis of Application6.1 Personnel Qualification:6.1.1 If specified by the contractual agreement, personnelperforming examinations to this test
20、 method shall be qualifiedin accordance with a nationally or internationally recognizedNDT personnel qualification standard such as ANSI/ASNT-CP-189, SNT-TC-1A, NAS-410, or a similar document andcertified by the employer or certifying agency, as applicable.The practice of the standard used and its a
21、pplicable revisionshall be specified in the contractual agreement between theusing parties.6.1.2 Qualification and certification for personnel may bereduced when the following conditions are met:6.1.2.1 The examination will be limited to operating equip-ment, which displays the results in percent IA
22、CS.6.1.2.2 A specific procedure is used that is approved by acertified Level III in accordance with 6.1.1.6.1.2.3 Documentation of training and examination is per-formed to ensure that personnel are qualified. Qualified per-sonnel are those who have demonstrated, by passing writtenand practical prof
23、iciency tests, that they possess the skills andjob knowledge necessary to ensure acceptable workmanship.6.2 Qualification of Nondestructive Testing AgenciesIfspecified in the contractual agreement, NDT agencies shall bequalified and evaluated as described in Practice E 543. Theapplicable edition of
24、Practice E 543 shall be specified in thecontractual agreement.6.3 The following additional items are subject to contractualagreement between the parties using or referencing this testmethod.6.3.1 Timing of Examination6.3.2 Extent of Examination6.3.3 Reporting Criteria/Acceptance Criteria6.3.4 Reexam
25、ination of Repaired/Reworked Items7. Variables Influencing Accuracy7.1 Consider the influence of the following variables toensure an accurate evaluation of electrical conductivity.7.1.1 TemperatureThe instrument, probe, reference stan-dards, and parts being examined shall be stabilized at ambienttem
26、perature prior to conductivity evaluation. When possible,examinations should be performed at room temperature (typi-cally 68 6 15F).7.1.2 Probe Coil to Metal CouplingVariations in theseparation between the probe coil and the surface of the sample(lift-off) can cause large changes in the instrument o
27、utputsignal. Instruments vary widely in sensitivity due to lift-off,and some have adjustments for minimizing it. Standardize theinstrument with values at least as large as the known lift-off.Surface curvature may also affect the coupling. (Consult themanufacturers manual for limitations on lift-off
28、and surfacecurvature).7.1.3 Edge EffectTests should not be performed withintwo coil diameters of any discontinuity, such as an edge, hole,or notch unless coil manufacturers instructions allow. Consultmanufacturers instructions to determine equipment limitationsfor inspection adjacent to any disconti
29、nuity. If no informationregarding probe use restrictions or limitations adjacent to suchdiscontinuities exist, examinations should not be performedwithin two coil diameters of any discontinuity.7.1.4 Uniformity of SampleVariations in material proper-ties are common and can be quite large. Discontinu
30、ities orinhomogeneities in the metal near the position of the probe coilwill change the value of the measured conductivity.NOTE 1Similar materials from various manufacturing methods (ex-trusion, forging, casting, rolling, machined vs. unmachined) may exhibitsignificant conductivity variation between
31、 processes.7.1.5 Surface ConditionsSurface treatments and rough-ness can affect the measured conductivity value of a material.Cladding also has a pronounced effect on conductivity readingsas compared to the base metal values. Procedures for deter-mining the electrical conductivity of clad materials
32、are notaddressed in this test method. The sample surface should beclean and free of grease.7.1.6 Instrument StabilityInstrument drift, noise, and non-linearities can cause inaccuracies in the measurement.7.1.7 Nonunique Conductivity ValuesIt should be notedthat two different alloys can have the same
33、 conductivity. Thus,in some cases, a measurement of conductivity may notuniquely characterize an alloy. Overheated parts and someheat-treated aluminum alloys are examples of materials thatmay have identical conductivity values for different heattreatments or tempers.7.1.8 Sample ThicknessEddy-curren
34、t density decreasesexponentially with depth (that is, distance from the metalE1004092surface). The depth at which the density is approximately 37 %(1/e) of its value at the surface is called the standard depth ofpenetration d. Calculate the standard depth of penetration fornonmagnetic materials usin
35、g one of the following formulas:d5503.3=fsm!, s51/r (1)d5K=1/r! frcm!, K.50, r51 (2)d51=psfm!, 5or, o54p31027, r51 (3)where:s = electrical conductivity of the sample in S/m,r = electrical resistivity in Vm, andf = examination frequency in Hz.These formulas are for nonmagnetic materials when therelat
36、ive permeability, rel=1. If the thickness of the sample andthe reference standards is at least 2.6d, the effect of thicknessis negligible. Smaller depths of penetration (higher frequen-cies) may be desirable for measuring surface effects. Theeddy-current density decrease with depth is also affected
37、by thecoil diameter. The change due to coil diameter variation is notconsidered in the above equation. Consult the instrumentmanufacturer if penetration depth appears to be a source oferror in the measurement.8. Apparatus8.1 Electronic ApparatusThe electronic apparatus shallbe capable of energizing
38、the probe coil with alternatingcurrents of suitable frequencies and power levels and shall becapable of sensing changes in the measured impedance of thecoil. Equipment may include any suitable signal-processingdevice (phase discriminator, filter circuits, and so forth). Theoutput may be displayed in
39、 either analog or digital readouts.Readout is normally in percent IACS although it may be scaledfor readings in other units. Additional apparatus, such ascomputers, plotters, or printers, or combination thereof, may beused in the recording of data.8.2 ProbeProbe coil designs combine empirical andmat
40、hematical design methods to choose appropriate combina-tions of characteristics. Many instruments use one probe coil.In instruments with several coils, the difference between coilsis the coil geometry. For most conductivity instruments, thecable connecting the coil to the instrument is an integral p
41、art ofthe measuring circuit and the cable length should not bemodified without consulting the instrument manufacturer ormanual.8.2.1 The probe coil should be designed to minimize theeffect of heat transfer from hand to coil.8.3 Mechanical handling apparatus for feeding the samplesor moving the probe
42、 coil, or both, may be used to automate aspecific measurement.9. Standardization and Calibration9.1 StandardizationTurn the instrument on and allow itsufficient time to stabilize in accordance with the manufactur-ers instructions. Adjust, balance, and standardize the conduc-tivity meter against the
43、instruments operational standards, andcompensate the conductivity meter for surface roughness andlift-off in accordance with the manufacturers instructions. If alift-off adjustment is not available, determine the acceptablerange of lift-off that will meet the accuracy requirements.Verify the standar
44、dization of the conductivity meter at periodicintervals (see Section 10).9.1.1 The instrument, probe, and reference standards shallbe standardized while maintaining the temperature within 5Fof the ambient temperature. It is desirable to perform thestandardization at room temperature (typically 70 6
45、15F).9.1.2 Instruments with two standardization adjustmentsshall be adjusted so that the known value of conductivity isobtained for both reference standards. The reference standardsused should have conductivities that bracket the conductivityvalue of the sample.9.1.3 Some instruments have only one s
46、tandardization ad-justment. In these cases the instrument should be standardizedto a reference standard at one end of the range to be examined.A reference standard at the other end of the range should beexamined to verify that the error is within acceptable limitsover the entire range.9.2 Reference
47、StandardsElectrical conductivity referencestandards are usually classified as primary, secondary, andoperational standards.9.2.1 Primary Conductivity StandardsThese are referencestandards that have been verified in terms of the fundamentalunits. The primary standards are kept in a laboratory environ
48、-ment and are used only to standardize secondary standards.9.2.2 Secondary Conductivity StandardsThese referencestandards have a value assigned through comparison withprimary standards. The primary standards used for assignmentof values to these secondary standards shall have been stan-dardized usin
49、g Test Method B 193. The secondary standardsare kept in a laboratory environment and are used only tocalibrate operational or instrument standards.9.2.3 Operational Conductivity StandardsThese refer-ence standards are standardized by comparison with secondarystandards. These reference standards are used to standardizethe instrument during use.9.3 Reference standards should be examined with a rela-tively small coil to determine the uniformity of electricalconductivity over the surface of the standard. Both the frontand the back surface shou
