ASTM E664E664M-15

Designation: E664/E664M − 15Standard 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, 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 practice describes a procedure for measuring theapparent attenuation of ultrasound 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 between 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 techniques.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-conformancewith 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 to use.2. Referenced Documents2.1 ASTM Standards:2E317 Practice for Evaluating Performance Characteristics ofUltrasonic Pulse-Echo Testing Instruments and Systemswithout the Use of Electronic Measurement InstrumentsE543 Specification for Agencies Performing NondestructiveTestingE1316 Terminology for Nondestructive Examinations2.2 Other Documents:SNT-TC-1A Recommended for Personnel Qualification andCertification of Nondestructive Testing Personnel3ANSI/ASNT CP-189 ASNT Standard for Qualification andCertification of Nondestructive Testing Personnel2NAS-410 NAS Certification and Qualification of Nonde-structive Personnel (Quality Assurance Committee)4ISO 9712 Non-destructive Testing—Qualification and Cer-tification of NDT Personnel53. Terminology3.1 Definitions—For definitions of terms used in thispractice, see Terminology E1316.4. Summary of Practice4.1 This practice describes a procedure for determiningapparent attenuation by measuring the decay of multiple backreflections 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 material 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 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.1This practice is under the jurisdiction of ASTM Committee E07 on Nonde-structive Testing and is the direct responsibility of Subcommittee E07.06 onUltrasonic Method.Current edition approved June 1, 2015. Published June 2015. Originallyapproved in 1978. Last previous edition approved in 2010 as E664 - 10. DOI:10.1520/E0664_E0664M-15.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at service@astm.org. For Annual Book of ASTMStandards volume information, refer to the standard’s Document 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., 1250 EyeSt., NW, Washington, DC 20005.5Available from International Organization for Standardization (ISO), 1, ch. dela Voie-Creuse, CP 56, CH-1211 Geneva 20, Switzerland, http://www.iso.org.*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 States16. Basis of Application6.1 The following items are subject to contractual agree-ment between the parties using or referencing this standard.6.2 Personnel Qualification6.2.1 If specified in the contract agreement, personnel per-forming examinations to this standard shall be qualified inaccordance with a nationally or internationally recognizedNDT personnel qualification practice or standard such asANSI/ASNT-CP-189, SNT-TC-1A, NAS-410, ISO 9712 orsimilar document and certified by the employer or certifyingagency, as applicable. The practice or standard used and itsapplicable revision shall be identified in the contractual agree-ment between the using parties.6.3 Qualification of Nondestructive Agencies—If specifiedin the contractual agreement, NDT agencies shall be qualifiedand evaluated as described in Specification E543. The appli-cable edition of Specification E543 shall be specified in thecontractual agreement.6.4 Procedures and Techniques—The procedures and tech-niques to be utilized shall be as specified in the contractualagreement.6.5 Timing of Examination—The timing of examinationshall be identified in the contractual agreement between theusing parties.6.6 Extent of Examination—The extent of the examinationshall be identified in the contractual agreement between theusing parties.6.7 Reporting Criteria/Acceptance Criteria—Reporting cri-teria for the examination results shall be in accordance withSection 10 unless otherwise specified. Since acceptance criteriaare not specified in this standard, they shall be specified in thecontractual agreement.6.8 Re-examination of Repair/Reworked Items—Re-examination of repaired/reworked items is not addressed in thisstandard and if required shall be specified in the contractualagreement.7. Apparatus7.1 Ultrasonic Flaw Detection System— A system capableof generating, receiving, and displaying ultrasonic energy atthe frequency of interest. Display shall be an A-scan presen-tation.7.1.1 Performance Characteristics—The vertical linearitylimits shall be determined as specified in Practice E317. Allmeasurements shall be made only within the linear ranges ofthe system.7.2 Search Unit—The size and frequency should be deter-mined to suit the application, and only non-focused searchunits may be used.7.3 Couplant—Normally water. See Terminology E1316.7.4 Reference Block—The 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 have acoustic properties similar to thoseof the examined material in the frequency range of interest.8. Specimen8.1 Geometric Similarity—When comparing the apparentattenuations of two or more materials or components, thespecimens used must be geometrically similar. They must beflat and parallel within 0.008 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 8.2.8.2 Minimum Dimensions—The thickness of the specimen(parallel to the ultrasonic beam) shall be of a dimension so thatat least 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 1—For 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 8.1 and 8.2 aresatisfied.9. Procedure9.1 Measure the thickness of the specimen to an accuracy of60.001 in. [60.03 mm] or 60.1 %, whichever is greater.9.2 Place the sample in a suitable immersion tank.9.3 Place the search unit in a fixture suitable for manipulat-ing the sound entry angle and lateral position. Position thesearch unit over the sample, and 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 2—If the frequency and dimensions of the transducers availabledo not readily permit the top surface of sample to be in the far field, thismethod may be used provided the back reflections measured and recordedare in the far field of the sound beam.9.3.1 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.NOTE 3—If the apparent attenuation of two or more materials orcomponents are to be compared, the same two back reflections should beselected for each sample.9.3.2 Determine the apparent attenuation by the relationshipindicated below. The apparent attenuation will be in terms ofdecibels per unit length as defined by the units of thickness.Apparent attenuation 520 log10AmAn2 ~n 2 m! Twhere:Amand An= amplitudes of the mth and nth back reflections(n m), andT = specimen thickness.NOTE 4—When instruments are used that have dB calibrated gaincontrol, the measurements in decibels may be used instead of 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:E664/E664M − 152dB2 ~n 2 m! T10. Report10.1 The report should include the following:10.1.1 Instrument make, model, and serial number,10.1.2 Pertinent equipment settings such as gain, pulselength, damping, etc.,10.1.3 Search unit type, frequency, serial number and trans-ducer size,10.1.4 Specimen dimensions,10.1.5 Amplitudes and numbers of each of the back reflec-tions used to calculate the attenuation parameter,10.1.6 Attenuation parameter, and10.1.7 Water path length.11. Keywords11.1 apparent attenuation; attenuation; immersion method;nondestructive examination; ultrasonic examinationSUMMARY OF CHANGESCommittee E07 has identified the location of selected changes to this standard since the last issue (E664) thatmay impact the use of this standard.(1) Section 2, Reference Documents—Removed E214, whichwas withdrawn in 2007.(2) Inserted Section 6, Basis of Application, and renumberedsubsequent sections.(3) Section 7.1, Apparatus—Removed “electrical pulses” andreplaced with “ultrasonic energy.” This conforms to the Ter-minology E1316-14 definition under “Apparent Attenuation.”(4) Section 7.3—Removed reference to E214 and referred toTerminology E1316.ASTM 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 infringement 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 standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views 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 service@astm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the Copyright Clearance Center, 222Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600; http://www.copyright.com/FIG. 1 Typical A-Scan Presentation Showing Multiple Back Reflections for Evaluation of Apparent Attenuation.E664/E664M − 153