1、Designation: E664/E664M 10Standard Practice for theMeasurement of the Apparent Attenuation of LongitudinalUltrasonic Waves by Immersion Method1This standard is issued under the fixed designation E664/E664M; the number immediately following the designation indicates the yearof original adoption or, i
2、n 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. Scope1.1 This practice describes a procedure for measuring theapparent attenuation of ultra
3、sound in materials or componentswith flat, parallel surfaces using conventional pulse-echoultrasonic flaw detection equipment in which reflected indica-tions are displayed in an A-scan presentation.1.2 The measurement procedure is readily adaptable for thedetermination of relative attenuation betwee
4、n materials. Forabsolute (true) attenuation measurements, indicative of theintrinsic nature of the material, it is necessary to correct forspecimen geometry, sound beam divergence, instrumentation,and procedural effects. These results can be obtained with morespecialized ultrasonic equipment and tec
5、hniques.1.3 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. The values stated ineach system may not be exact equivalents; therefore, eachsystem shall be used independently of the other. Combiningvalues from the two systems may result in non-conforma
6、ncewith the standard.1.4 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 appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior t
7、o use.2. Referenced Documents2.1 ASTM Standards:2E214 Practice for Immersed Ultrasonic Testing by theReflection Method Using Pulsed Longitudinal Waves3E317 Practice for Evaluating Performance Characteristicsof Ultrasonic Pulse-Echo Testing Instruments and Systemswithout the Use of Electronic Measure
8、ment InstrumentsE1316 Terminology for Nondestructive Examinations3. Terminology3.1 DefinitionsFor definitions of terms used in this prac-tice, see Terminology E1316.4. Summary of Practice4.1 This practice describes a procedure for determiningapparent attenuation by measuring the decay of multiple ba
9、ckreflections of longitudinal ultrasonic waves introduced intospecimens with flat, parallel surfaces by the immersion tech-nique.5. Significance and Use5.1 The measurement of apparent attenuation in materials isuseful in applications such as the comparison of heat treat-ments of different lots of ma
10、terial or the assessment of thedegradation of materials due to environment.5.2 Several different modes of wave vibration can bepropagated in solids. This practice is concerned with theattenuation associated with longitudinal waves introduced intothe specimen by the immersion method.5.3 This practice
11、 allows for the comparison of the apparentattenuations of geometrically similar specimens.5.4 For the determination of apparent attenuation, the pro-cedures described herein are valid only for measurements inthe far field of the ultrasonic beam.6. Apparatus6.1 Ultrasonic Flaw Detection System A syst
12、em capableof generating, receiving, and displaying electrical pulses at thefrequency of interest. Display shall be an A-scan presentation.6.1.1 Performance CharacteristicsThe vertical linearitylimits shall be determined as specified in Practice E317. Allmeasurements shall be made only within the lin
13、ear ranges ofthe system.6.2 Search UnitThe size and frequency should be deter-mined to suit the application, and only non-focused searchunits may be used.1This practice is under the jurisdiction of ASTM Committee E07 on Nonde-structive Testing and is the direct responsibility of Subcommittee E07.06
14、onUltrasonic Method.Current edition approved June 1, 2010. Published July 2010. Originally approvedin 1978. Last previous edition approved in 2005 as E664 - 93(2005). DOI:10.1520/E0664_E0664M-10.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at
15、serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Withdrawn. The last approved version of this historical standard is referencedon www.astm.org.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West
16、 Conshohocken, PA 19428-2959, United States.6.3 CouplantNormally water. See Practice E214 for alter-natives.6.4 Reference BlockThe use of a reference block issuggested to evaluate the stability of the measurement systemif measurements will be made over a period of time. Thereference block should hav
17、e acoustic properties similar to thoseof the examined material in the frequency range of interest.7. Specimen7.1 Geometric SimilarityWhen comparing the apparentattenuations of two or more materials or components, thespecimens used must be geometrically similar. They must beflat and parallel within 0
18、.008 in. 0.20 mm/in. 25.4 mm ofdiameter or cross section and differ in thickness by no morethan a factor of 2. The cross section of each specimen mustmeet the requirements of 7.2.7.2 Minimum DimensionsThe thickness of the specimen(parallel to the ultrasonic beam) shall be of a dimension so thatat le
19、ast two back surface reflections can be resolved at thefrequency of interest. The dimensions normal to the ultrasonicbeam shall be much greater than the beam width and wave-length (at least three times the transducer dimension) so thatside wall echoes do not interfere with the measurements.NOTE 1For
20、 the determination of true attenuation, careful consider-ation must be made of parameters such as front surface and back surfaceparallelism, surface finish, etc. However, useful apparent attenuationinformation can be obtained if the requirements of 7.1 and 7.2 aresatisfied.8. Procedure8.1 Measure th
21、e thickness of the specimen to an accuracy of60.001 in. 60.03 mm or 60.1 %, whichever is greater.8.2 Place the sample in a suitable immersion tank.8.3 Place the search unit in a fixture suitable for manipulat-ing the sound entry angle and lateral position. Position thesearch unit over the sample, an
22、d angulate the beam to obtainthe maximum number of back reflections. See Fig. 1. The waterpath should be such that the entry surface is in the far field ofthe ultrasonic beam.NOTE 2If the frequency and dimensions of the transducers availabledo not readily permit the top surface of sample to be in th
23、e far field, thismethod may be used provided the back reflections measured and recordedare in the far field of the sound beam.8.3.1 With the reject level set at zero, measure and recordthe amplitudes of any two back reflections that show decreas-ing amplitude with increase in back reflection number.
24、NOTE 3If the apparent attenuation of two or more materials orcomponents are to be compared, the same two back reflections should beselected for each sample.8.3.2 Determine the apparent attenuation by the relationshipindicated below. The apparent attenuation will be in terms ofdecibels per unit lengt
25、h as defined by the units of thickness.Apparent attenuation 520 log10AmAn2 n 2 m! Twhere:Amand An= amplitudes of the mth and nth back reflec-tions (n m), andT = specimen thickness.NOTE 4When instruments are used that have dB calibrated gaincontrol, the measurements in decibels may be used instead of
26、 amplitudemeasurements. The dB control is used to bring the amplitude of the nthreflection up to the amplitude of the mth reflection and the gain in decibelsis substituted for the numerator in the attenuation formula. The formulathen becomes:dB2 n 2 m! T9. Report9.1 The report should include the fol
27、lowing:9.1.1 Instrument make, model, and serial number,9.1.2 Pertinent equipment settings such as gain, pulselength, damping, etc.,9.1.3 Search unit type, frequency, serial number and trans-ducer size,9.1.4 Specimen dimensions,9.1.5 Amplitudes and numbers of each of the back reflec-tions used to cal
28、culate the attenuation parameter,9.1.6 Attenuation parameter, andFIG. 1 Typical A-Scan Presentation Showing Multiple Back Reflections for Evaluation of Apparent Attenuation.E664/E664M 1029.1.7 Water path length.10. Keywords10.1 apparent attenuation; attenuation; immersion method;nondestructive exami
29、nation; ultrasonic examinationASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof in
30、fringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this stan
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32、iews known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).E664/E664M 103
