1、Designation: E494 10E494 15Standard Practice forMeasuring Ultrasonic Velocity in Materials1This standard is issued under the fixed designation E494; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A numbe
2、r 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 U.S. Department of Defense.1. Scope*1.1 This practice covers a test procedure for measuring u
3、ltrasonic velocities in materials with conventional ultrasonic pulse echoflaw detection equipment in which results are displayed in an A-scan display. This practice describes a method whereby unknownultrasonic velocities in a material sample are determined by comparative measurements using a referen
4、ce material whose ultrasonicvelocities are accurately known.1.2 This procedure is intended for solid materials 5 mm (0.2 in.) (0.2 in.) thick or greater. The surfaces normal to the directionof energy propagation shall be parallel to at least 63. Surface finish for velocity measurements shall be 3.2
5、m (125 in.) rmsroot-mean-square (rms) or smoother.NOTE 1Sound wave velocities are cited in this practice using the fundamental units of metres per second, with inches per second supplied forreference in many cases. For some calculations, it is convenient to think of velocities in units of millimetre
6、s per microsecond. While these units worknicely in the calculations, the more natural units were chosen for use in the tables in this practice. The values can be simply converted from m/s to mm/sby moving the decimal point three places to the left, that is, 3500 m/s becomes 3.5 mm/s.1.3 Ultrasonic v
7、elocity measurements are useful for determining several important material properties. Youngs modulus ofelasticity, Poissons ratio, acoustic impedance, and several other useful properties and coefficients can be calculated for solidmaterials with the ultrasonic velocities if the density is known (se
8、e Appendix X1).1.4 More accurate results can be obtained with more specialized ultrasonic equipment, auxiliary equipment, and specializedtechniques. Some of the supplemental techniques are described in Appendix X2. (Material contained in Appendix X2 is forinformational purposes only.)NOTE 2Factors i
9、ncluding techniques, equipment, types of material, and operator variables will result in variations in absolute velocity readings,sometimes by as much as 5 %. Relative results with a single combination of the above factors can be expected to be much more accurate (probably withina 1 % tolerance).1.5
10、 The values stated in SI units are to be 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 responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applica
11、bility of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C597 Test Method for Pulse Velocity Through ConcreteE317 Practice for Evaluating Performance Characteristics of Ultrasonic Pulse-EchoTesting Instruments and Systems without theUse of Electronic Measurement Instru
12、mentsE543 Specification for Agencies Performing Nondestructive TestingE797 Practice for Measuring Thickness by Manual Ultrasonic Pulse-Echo Contact MethodE1316 Terminology for Nondestructive Examinations1 This practice is under the jurisdiction ofASTM Committee E07 on Nondestructive Testing and is t
13、he direct responsibility of Subcommittee E07.06 on Ultrasonic Method.Current edition approved Sept. 1, 2010Dec. 1, 2015. Published October 2010December 2015. Originally approved in 1973. Last previous edition approved in 20012010as E494 - 05.E494 - 10. DOI: 10.1520/E0494-10.10.1520/E0494-15.2 For re
14、ferencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide
15、 the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit 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 versionof the sta
16、ndard as published by ASTM is to be considered the official document.*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 States12.2 ASNT Documents:3SNT-TC-1A Recommended Practice f
17、or Nondestructive Testing Personnel Qualification and CertificationASNI/ASNT-CP-189 Standard for Qualification and Certification of Nondestructive Testing Personnel2.3 AIA Document:4NAS-410 Certification and Qualification of Nondestructive Testing Personnel2.4 ISO Standard:5ISO 9712 Non-Destructive
18、TestingQualification and Certification of NDT Personnel3. Terminology3.1 DefinitionsFor definitions of terms used in this practice, see Terminology E1316.4. Summary of Practice4.1 Several possible modes of vibration can propagate in solids. This procedure is concerned with two velocities of propagat
19、ion,namely those associated with longitudinal (vl) and transverse (vt) waves. The longitudinal velocity is independent of samplegeometry when the dimensions at right angles to the beam are very large compared with beam area and wave length.The transversevelocity is little affected by physical dimens
20、ions of the sample. The procedure described in Section 8 is, as noted in the scope, foruse with conventional pulse echo flaw detection equipment only.5. Significance and Use5.1 This practice describes a test procedure for the application of conventional ultrasonic methods to determine velocity inmat
21、erials wherein unknown ultrasonic velocities in a material sample are determined by comparative measurements using areference material whose ultrasonic velocities are accurately known.5.2 Although not all methods described in this practice are applied equally or universally to all velocity measureme
22、nts indifferent materials, it does provide flexibility and a basis for establishing contractual criteria between users, and may be used asa general guideline for preparing a detailed procedure or specification for a particular application.5.3 This practice is directed towards the determination of lo
23、ngitudinal and shear wave velocities using the appropriate soundwave form. This practice also outlines methods to determine elastic modulus and can be applied in both contact and immersionmode.6. Basis of Application6.1 The following items are subject to contractual agreement between the parties usi
24、ng or referencing this practice:6.2 Personnel QualificationIf specified in the contractual agreement, personnel performing to this practice shall be qualifiedin accordance with a nationally or internationally recognized NDT personnel qualification practice or standard such asASNI/ASNT-CP-189, SNT-TC
25、-1A, NAS-410, ISO 9712, or a similar document and certified by the employer or certifying agency,as applicable. The practice or standard used and its applicable revision shall be identified in the contractual agreement betweenthe using parties.6.3 Qualification of Nondestructive AgenciesIf specified
26、 in the contractual agreement, NDT agencies shall be qualified andevaluated as described in Practice E543. The applicable edition of Practice E543 shall be specified in the contractual agreement.7. Apparatus7.1 The ultrasonic testing system to be used in this practice shall include the following:7.1
27、.1 Test InstrumentAny ultrasonic instrument comprising a time base, transmitter (pulser), receiver (echo amplifier), and anA-scan indicator circuit to generate, receive, and display electrical signals related to ultrasonic waves. Equipment shall allowreading the positions of Ak, As, At, Al (defined
28、in 8.1.4 and 8.2.4), along the A-scan base line within 60.5 mm (0.020 in.). Formaximum accuracy, the highest possible frequency that will present at least two easily distinguishable back echo reflections, andpreferably five, shall be used.7.1.2 Search UnitThe search unit containing a search unit tha
29、t generates and receivesshall generate and receive ultrasonicwaves of an appropriate size, type, and frequency, designed for tests by the contact method shall be used. method. Contact straightbeam longitudinal mode shall be used for longitudinal velocity measurements, and contact straight beam shear
30、 mode for transversevelocity measurements.3 Available from American Society for Nondestructive Testing (ASNT), P.O. Box 28518, 1711 Arlingate Ln., Columbus, OH 43228-0518, http:/www.asnt.org.4 Available from Aerospace Industries Association of America, Inc. (AIA), 1250 Eye St., NW, Washington, DC 20
31、005.5 Available from International Organization for Standardization (ISO), ISO Central Secretariat, BIBC II, Chemin de Blandonnet 8, CP 401, 1214 Vernier, Geneva,Switzerland, http:/www.iso.org.E494 1527.1.3 CouplantFor longitudinal velocity measurements, the couplant should be the material used in p
32、ractice, for example,clean light-grade oil. For transverse velocity measurements, a high viscosity material such as resin or solid bond shallshould beused. In some materials isopolybutene, honey, or other high-viscosity materials have been used effectively. Most liquids will notsupport transverse wa
33、ves. In porous materials special nonliquid couplants are required. The couplant must not be deleterious tothe material.7.1.4 Standard Reference Blocks:7.1.4.1 Velocity StandardAny material of known velocity, that can be penetrated by the acoustical wave, and that has anappropriate surface roughness,
34、 shape, thickness, and parallelism. The velocity of the standard should be determined by some othertechnique of higher accuracy, or by comparison with water velocity that is known (see Appendix X2.5 and Appendix X4). Thereference block should have an attenuation similar to that of the test material.
35、7.1.4.2 For horizontal linearity check, see Practice E317.8. Procedure8.1 Longitudinal Wave VelocityDetermine bulk, longitudinal wave velocity (vl) by comparing the transit time of a longitudinalwave in the unknown material to the transit time of ultrasound in a known velocity standard (vk).8.1.1 Se
36、lect samples of each with flat parallel surfaces and measure the thickness of each to an accuracy of 60.02 mm (0.001in.) or 0.1 %, whichever is greater.8.1.2 Align the search unit over each sample and obtain a nominal signal pattern (see Fig. 1) of as many back echoes as areclearly defined. The time
37、 base (sweep control) must be set the same for both measurements.8.1.3 Using a scale or caliper measure the distance at the base line between the leading edge of the first back echo and theleading edge of the last back echo that is clearly defined on the known and unknown sample. For better accuracy
38、, adjust theamplitude of the last back echo by means of the gain control to approximately the same height as the first back echo, after theposition of the leading edge of the first back echo has been fixed. This allows more accurate time or distance measurements. Theposition of the leading edge of t
39、he last back echo is then determined. The signal has traversed a distance twice the thickness ofthe specimen between each back echo. The signal traversing the specimen and returning is called a round trip. In Fig. 1 the signalhas made six round trips between Echo 1 and Echo 7. Count the number of ro
40、und trips from first echo used to the last echomeasured on both samples. This number will be one less than the number of echoes used. Note that the sample thickness, numberof round trips, and distance from front to last back echo measured need not be the same.8.1.4 Calculate the value of the unknown
41、 velocity as follows:v15Ak nl tl vk!/Al nk tk! (1)where:A k = distance from first to Nth back echo on the known material, m (in.), measured along the baseline of the A-scan display,nl = number of round trips, unknown material,tl = thickness of unknown material, m (in.),vk = velocity in known materia
42、l, m/s (in./s),Al = distance from the first to the Nth back echo on the unknown material, m (in.), measured along the baseline of the A-scandisplay,nk = number of round trips, known material, andtk = thickness, known material, m (in.).NOTE 3The units used in measurement are not significant as long a
43、s the system is consistent.8.2 Transverse VelocityDetermine transverse velocity (vs) by comparing the transit time of a transverse wave in an unknownmaterial to the transit time of a transverse wave in a material of known velocity (vt).8.2.1 Select samples of each with flat parallel surfaces and mea
44、sure the thickness of each to an accuracy of 60.02 mm (0.001in.) or 0.1 %, whichever is greater.8.2.2 Align the search unit (see Fig. 1) over each sample and obtain an optimum signal pattern of as many back echoes as areclearly defined. The time base (sweep control) must be the same for both measure
45、ments.FIG. 1 Initial Pulse and 7 Back EchoesE494 1538.2.3 Using a scale or caliper measure the distance at the base line between the leading edge of the first back echo and theleading edge of the last back echo that is clearly defined on the known and unknown sample. For better accuracy, adjust thea
46、mplitude of the last back echo by means of the gain control to approximately the same height as the first back echo, after theposition of the leading edge of the first back echo has been fixed. This adds high-frequency components of the signal which havebeen attenuated. Then determine the position o
47、f the leading edge of the last back echo. Count the number of round trips from firstecho used to the last echo measured on both samples. This number will be one less than the number of echoes used. Note that thesample thickness, number of round trips, and distance from first to last back echo measur
48、ed need not be the same.8.2.4 Calculate the value of the unknown velocity as follows:vs 5At ns ts vt!/As nt tt! (2)where:At = distance from first to Nth back echo on the known material, m (in.), measured along the baseline of the A-scan display,ns = number of round trips, unknown material,ts = thick
49、ness of unknown material, m (in.),vt = velocity of transverse wave in known material, m/s (in./s),As = distance from the first to the Nth back echo on the unknown material, m (in.), measured along the baseline of the A-scandisplay,nt = number of round trips, known material, andtt = thickness, known material, m (in.). (See Note 3).9. Report9.1 The following are data which should be included in a report on velocity measurements:9.1.1 Longitudinal Wave:9.1.1.1 Ak = _m (in.)9.1.1.2 nl = _9.1.1.3 tl = _m (in.)9.1.1.4 vk = _ms (
