ASTM E114-1995(2005) Standard Practice for Ultrasonic Pulse-Echo Straight-Beam Examination by the Contact Method《用接触法做超声脉冲回波纵波检验》.pdf

1、Designation: E 114 95 (Reapproved 2005)Standard Practice forUltrasonic Pulse-Echo Straight-Beam Examination by theContact Method1This standard is issued under the fixed designation E 114; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revis

2、ion, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) 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. Scope1.1 This practice2cover

3、s ultrasonic examination of materi-als by the pulse-echo method using straight-beam longitudinalwaves introduced by direct contact of the search unit with thematerial being examined.1.2 This practice shall be applicable to development of anexamination procedure agreed upon by the users of thedocumen

4、t.1.3 The values stated in inch-pound units are to be regardedas 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 deter

5、mine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:3E 317 Practice for Evaluating Performance Characteristicsof Ultrasonic Pulse-Echo Examination Instruments andSystems without the Use of Electronic Measurement In-strumentsE 543 Practice for Agen

6、cies Performing NondestructiveTestingE 1316 Terminology for Nondestructive Testing2.2 ASNT Standards:4SNT-TC-1A Recommended Practice for Personnel Qualifi-cation and Certification in Nondestructive TestingANSI/ASNT CP-189 ASNT Standard for Qualification andCertification of Nondestructive Testing Per

7、sonnel2.3 Other Documents:NAS-410 Certification and Qualification of NondestructiveTest Personnel53. Terminology3.1 Refer to Terminology E 1316 for definitions of termsused in this practice.4. Basis of Application4.1 Purchaser-Supplier Agreements:The following items require agreement between the usi

8、ngparties for this practice to be used effectively:4.1.1 Qualification of Nondestructive Testing AgenciesAgreement is required as to whether the nondestructive testingagency, as defined in Practice E 543 must be formally evalu-ated and qualified to perform the examination. If such evalu-ation and qu

9、alification is specified, a documented proceduresuch as Practice E 543 shall be used as the basis for evaluation.4.1.2 Personnel QualificationNondestructive testing(NDT) personnel shall be qualified in accordance with anationally recognized NDT personnel qualification practice orstandard such asANSI

10、/ASNT CP-189, SNT-TC-1A, NAS-410,or a similar document. The practice or standard used and itsapplicable revision shall be specified in the contractual agree-ment between the using parties.4.1.3 Extent of ExaminationThe extent of the examina-tion shall be determined by agreement of the using parties.

11、4.1.4 Time of ExaminationThe time of examination shallbe determined by agreement of the using parties.4.1.5 Interpretation CriteriaThe criteria by which theultrasonic signals and part acceptability will be evaluated andshall be determined by agreement of the using parties.5. Significance and Use5.1

12、A series of electrical pulses is applied to a piezoelectricelement (transducer) which converts these pulses to mechani-cal energy in the form of pulsed waves at a nominal frequency.This transducer is mounted in a holder so it can transmit the1This practice is under the jurisdiction of ASTM Committee

13、 E07 on Nonde-structive Testing and is the direct responsibility of Subcommittee E07.06 onUltrasonic Method.Current edition approved Dec. 1, 2005. Published February 2006. Originallyapproved in 1955. Last previous edition approved in 2001 as E 114 - 95 (2001).2For ASME Boiler and Pressure Vessel Cod

14、e applications see related PracticeSE-114 in Section II of that Code.3For 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 Document Summary page onthe ASTM

15、website.4Available fromAmerican Society for Nondestructive Testing (ASNT), P.O. Box28518, 1711 Arlingate Ln., Columbus, OH 43228-0518.5Available from Aerospace Industries Association of America, Inc. (AIA), 1250Eye St., NW, Washington, DC 20005.1Copyright ASTM International, 100 Barr Harbor Drive, P

16、O Box C700, West Conshohocken, PA 19428-2959, United States.waves into the material through a suitable wear surface andcouplant. The assembly of transducer, holder, wearface, andelectrical connnector comprise the search unit.5.2 Pulsed energy is transmitted into materials, travels in adirection norm

17、al to the contacted surface, and is reflected backto the search unit by discontinuity or boundary interfaceswhich are parallel or near parallel to the contacted surface.These echoes return to the search unit, where they areconverted from mechanical to electrical energy and are ampli-fied by a receiv

18、er. The amplified echoes (signals) are usuallypresented in an A-scan display, such that the entire round tripof pulsed energy within the resolution of the system may beindicated along the horizontal base line of the display byvertical deflections corresponding to echo amplitudes fromeach interface,

19、including those from intervening discontinui-ties. By adjustment of the sweep (range) controls, this displaycan be expanded or contracted to obtain a designated relationbetween the displayed signals and the material reflectors fromwhich the signal originates. Thus a scaled distance to adiscontinuity

20、 and its displayed signal becomes a true relation-ship. By comparison of the displayed discontinuity signalamplitudes to those from a reference standard, both locationand estimated discontinuity size may be determined. Discon-tinuities having dimensions exceeding the size of the soundbeam can also b

21、e estimated by determining the amount ofmovement of a search unit over the examination surface wherea discontinuity signal is maintained.NOTE 1When determining the sizes of discontinuities by either ofthese two practices, only the area of the discontinuity which reflectsenergy to the search unit is

22、determined.5.3 Types of information that may be obtained from thepulsed-echo straight-beam practice are as follows:5.3.1 Apparent discontinuity size (Note 2) by comparison ofthe signal amplitudes from the test piece to the amplitudesobtained from a reference standard.5.3.2 Depth location of disconti

23、nuities by calibrating thehorizontal scale of the A-scan display.5.3.3 Material properties as indicated by the relative soundattenuation or velocity changes of compared items.5.3.4 The extent of bond and unbond (or fusion and lack offusion) between two ultrasonic conducting materials if geom-etry an

24、d materials permit.NOTE 2The term “apparent” is emphasized since true size depends onorientation, composition, and geometry of the discontinuity and equip-ment limitations.6. Apparatus6.1 Complete ultrasonic apparatus shall include the follow-ing:6.1.1 InstrumentationThe ultrasonic instrument shall

25、becapable of generating, receiving, and amplifying high-frequency electrical pulses at such frequencies and energylevels required to perform a meaningful examination and toprovide a suitable readout.6.1.2 Search UnitsThe ultrasonic search units shall becapable of transmitting and receiving ultrasoun

26、d in the materialat the required frequencies and energy levels necessary fordiscontinuity detection. Typical search unit sizes usually rangefrom18 in. 3.2 mm in diameter to 118 in. 28.6 mm indiameter with both smaller and larger sizes available forspecific applications. Search units may be fitted wi

27、th specialshoes for appropriate applications. Special search units encom-passing both a transmitter and a receiver as separate piezoelec-tric elements can be utilized to provide some degree ofimproved resolution near the examination surface.6.1.3 CouplantAcouplant, usually a liquid or semi-liquid,is

28、 required between the face of the search unit and theexamination surface to permit or improve the transmittance ofultrasound from the search unit into the material under test.Typical couplants include water, cellulose gel, oil, and grease.Corrosion inhibitors or wetting agents or both may be used.Co

29、uplants must be selected that are not detrimental to theproduct or the process. The couplant used in standardizationshould be used for the examination. During the performance ofa contact ultrasonic examination, the couplant layer betweensearch unit and examination material must be maintained suchtha

30、t the contact area is held constant while maintainingadequate couplant thickness. Lack of couplant reducing theeffective contact area or excess couplant thickness will reducethe amount of energy transferred between the search unit andthe examination piece. These couplant variations in turn resultin

31、examination sensitivity variations.6.1.3.1 The couplant should be selected so that its viscosityis appropriate for the surface finish of the material to beexamined. The examination of rough surfaces generally re-quires a high-viscosity couplant. The temperature of thematerials surface can change the

32、 couplants viscosity. As anexample, in the case of oil and greases, see Table 1.6.1.3.2 At elevated temperatures as conditions warrant,heat-resistant coupling materials such as silicone oils, gels, orgreases should be used. Further, intermittent contact of thesearch unit with the surface or auxiliar

33、y cooling of the searchunit may be necessary to avoid temperature changes that affectthe ultrasonic wave characteristics of the search unit. At highertemperatures, certain couplants based on inorganic salts orthermoplastic organic materials, high-temperature delay mate-rials, and search units that a

34、re not damaged by high tempera-tures may be required.6.1.3.3 Where constant coupling over large areas is needed,as in automated examination, or where severe changes insurface roughness are found, other couplants such as liquid gapcoupling will usually provide a better examination. In this case,the s

35、earch unit does not contact the examination surface but isseparated by a distance of about 0.2 in. 0.5 mm filled withTABLE 1 Suggested ViscositiesOil CouplantsNOTE 1The table is a guide only and is not meant to exclude the useof a particular couplant that is found to work satisfactorily on a particu

36、larsurface.Approximate Surface Roughness Average(Ra), in. mEquivalent Couplant Vis-cosity, Weight Motor Oil5100 0.12.5 SAE 1050200 1.35.1 SAE 20100400 2.510.2 SAE 30250700 6.417.8 SAE 40Over 700 18 cup greaseE 114 95 (2005)2couplant. Liquid flowing through the search unit fills the gap.The flowing l

37、iquid provides the coupling path and has theadditional advantage of cooling the search unit if the exami-nation surface is hot.6.1.3.4 An alternative means of direct contact coupling isprovided by the wheel search unit. The search unit is mountedat the required angle to a stationary axle about which

38、 rotates aliquid-filled flexible tire. A minimum amount of couplantprovides ultrasonic transmission into the examination surfacesince the elastic tire material is in rolling contact and conformsclosely to the surface.6.1.4 Reference StandardsThe production item itself maybe an adequate standard usin

39、g the height of the back wall echofor reference. For more quantitative information, machinedartificial reflectors (discontinuities) or charts representingdistance-amplitude relationships of known reflector sizes for aparticular search unit and material may be used for standard-ization. These artific

40、ial reflectors may be in the form offlat-bottom holes, side-drilled holes, or slots. An alternatemethod of fabricating a reference standard may be the intro-duction of known discontinuities during the fabrication processof a production item or other convenient configuration. Thesurface finish of the

41、 reference standard should be similar to thesurface finish of the production item (or corrected; see 7.3).The reference standard material and the production materialshould be acoustically similar (in velocity and attenuation).The reference standard selected shall be used by the examineras the basis

42、for signal comparisons.7. Standardization of Apparatus7.1 If quantitative information is to be obtained, vertical orhorizontal linearity or both should be checked in accordancewith Practice E 317 or another procedure approved by the usersof the document. An acceptable linearity performance may beagr

43、eed upon by the users of the document.7.2 Prior to examination, standardize the system in accor-dance with the product specification.7.3 Where the surface finishes of the reference standard andthe production item do not match, or where there is an acousticdifference between the standard and the prod

44、uction item, anattenuation correction should be made to compensate for thedifference. The attenuation correction is accomplished bynoting the difference between signals received from the samereference reflector (that is, back reflection) in the basic stan-dardization (reference) block and in the pro

45、duction material,and correcting for this difference.7.4 It should be recognized that near-field effects may causesensitivity inconsistencies when searching for inhomogeneitiessmaller than the effective beam diameter. Suitable delay linesearch units or other means such as examining from both sidesof

46、the item may be considered where the application warrantsfine scrutiny. When performing examinations in the far-field, itis recommended that compensation be made for the acousticattenuation of the test material with respect to a certainreference standard. This compensation may be accomplishedwith mu

47、ltiple depth reference reflectors, electronically, withattenuation curves drawn on the face of the A-scan display, orwith charts for distance-amplitude relationships of knownreflectors. For optimum examination performance, compensa-tions should be made for both near and far-field effects.7.5 Unless

48、otherwise specified, the initial pulse and at leastone back reflection shall appear on the A-scan display whileexamining for discontinuities in materials having parallelsurfaces. The total number of back reflections depends uponequipment, geometry and material type, information desired, oroperator p

49、reference. Reduction of the back reflection duringscanning is indicative of increased attenuation or sound scat-tering discontinuities provided that front and back surfaceroughness and parallelism of the production piece are approxi-mately the same as that of the standard. For non-parallelsurfaces, the time trace of the display shall be standardized byusing standards that include the maximum thickness of theproduction item being examined.7.6 For bond/unbond (fusion/lack of fusion) examinations, areference standard should be used similar to