1、Designation:E162912Standard Practice forDetermining the Impedance of Absolute Eddy-CurrentProbes1This standard is issued under the fixed designation E1629;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A nu
2、mber in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope*1.1 This practice covers a procedure for determining theimpedance of absolute eddy-current probes(bridge-type,air orferrite core,wire wound,shie
3、lded,or unshielded)used forfinding material defects in electrically conducting material.This practice is intended to establish a uniform methodology tomeasure the impedance of eddy-current probes prior to receiptof these probes by the purchaser or the specifier.1.2 LimitationsThis practice does not
4、address the charac-terization or measurement of the impedance of differential,a-ccoupled,or transmit/receive types of probes.This practice doesnot address the use of magnetic materials in examinationprobes.This practice shall not be used as a basis for selectionof the best probe for a particular app
5、lication or as a means bywhich to calibrate or standardize a probe for a specificexamination.This practice does not address differences in theimpedance values that can be obtained when the probe andmaterial are in relative motion,as in a rotating probe,since theprocedure described here requires the
6、probe and material to bestationary.1.3 UnitsThe values stated in SI units are to be regardedas the standard.The values given in parentheses are mathemati-cal conversions to inch-pound units that are provided forinformation only and are not considered standard.1.4 This standard does not purport to ad
7、dress all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 The following document forms a p
8、art of this practice tothe extent specified herein:2.2 ASTM Standards:E1316 Terminology for Nondestructive Examinations23.Terminology3.1 DefinitionsDefinitions of terms relating to electromag-netic examination are given in Terminology E1316.3.2 Definitions of Terms Specific to This Standard:3.2.1 ed
9、dy-current reference standard for the purposes ofthe method described in this practice,a rectangular block madeof an aluminum alloy(see 6.1.2)to which an active eddy-current probe is applied.The eddy-current reference standardcan also be referred to as an eddy-current test block.3.3 Mathematical Sym
10、bols:3.3.1 ja symbol used in electrical engineering to represent=21.It is associated with the restriction to the flow ofelectrical current caused by capacitors and coils.3.3.2 N any number.3.3.3|N|the magnitude of N,regardless whether N ispositive,negative,or a vector quantity.3.3.4=N the square roo
11、t of N.3.3.5(N)2N squared,that is,N N.3.3.6 N delta N,the change or difference in N.3.4 Abbreviations:3.4.1 tanused for the tangent function.The tan1,arctangent or inverse tangent function,returns a value that is ameasure of an angle and can be in either degrees or radians.When using a calculator to
12、 determine the tan1,care should betaken to determine whether the answer is in degrees or radianssince the numerical values that represent the same angle aredifferent.3.4.2 cosused for the cosine function.3.4.3 sinused for the sine function.4.Significance and Use4.1 Eddy-current probes may be used fo
13、r the nondestructiveexamination of parts or structures made of electrically conduct-ing materials.Many of these examinations are intended to1This practice is under the jurisdiction of ASTM Committee E07 on Nonde-structive Testing and is the direct responsibility of Subcommittee E07.07 onElectromagne
14、tic Method.Current edition approved Nov.1,2012.Published November 2012.Originallyapproved in 1994.Last previous edition approved in 2007 as E1629-07.DOI:10.1520/E1629-12.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual B
15、ook of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 discover material def
16、ects,such as cracks,that may cause thepart or structure to be unsafe or unfit for service.Eddy-currentprobes that fail to meet the performance level requirements ofthis practice shall not be used for the examination of materialor hardware unless the probe is qualified by some other systemor an agreement has been reached by the probe manufacturerand the purchaser,or both.5.General Practice5.1 Use of Eddy-Current Reference StandardsThe eddy-current reference standards described in this practice sh
