1、Designation: E1901 13Standard Guide forDetection and Evaluation of Discontinuities by ContactPulse-Echo Straight-Beam Ultrasonic Methods1This standard is issued under the fixed designation E1901; the number immediately following the designation indicates the year oforiginal adoption or, in the case
2、of revision, the year of last revision. A number 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 guide covers procedures for the contact ultrasonicexamination of bulk materials or part
3、s by transmitting pulsedultrasonic waves into the material and observing the indica-tions of reflected waves. This guide covers only examinationsin which one search unit is used as both transmitter andreceiver (pulse-echo). This guide includes general require-ments and procedures that may be used fo
4、r detectingdiscontinuities, locating depth and distance from a point ofreference and for making a relative or approximate evaluationof the size of discontinuities as compared to a referencestandard.1.2 This guide complements Practice E114 by providingmore detailed procedures for the selection and ca
5、libration ofthe inspection system and for evaluation of the indicationsobtained.1.3 The values stated in inch-pound units are to be regardedas standard. The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.1.4 T
6、his guide does not purport to address all of the safetyconcerns, if any, associated with its use. It is the responsibilityof the user of this guide to establish the appropriate safety andhealth practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1
7、 ASTM Standards:2E114 Practice for Ultrasonic Pulse-Echo Straight-BeamContact TestingE127 Practice for Fabricating and Checking Aluminum Al-loy Ultrasonic Standard Reference BlocksE317 Practice for Evaluating Performance Characteristics ofUltrasonic Pulse-Echo Testing Instruments and Systemswithout
8、the Use of Electronic Measurement InstrumentsE428 Practice for Fabrication and Control of Metal, Otherthan Aluminum, Reference Blocks Used in UltrasonicTestingE543 Specification for Agencies Performing NondestructiveTestingE1158 Guide for Material Selection and Fabrication ofReference Blocks for the
9、 Pulsed Longitudinal Wave Ul-trasonic Testing of Metal and Metal Alloy ProductionMaterialE1316 Terminology for Nondestructive Examinations2.2 ASNT Standard:SNT-TC-1A Recommended Practice for Personnel Qualifi-cation and Certification in Nondestructive Testing Person-nel32.3 ANSI/ASNT Standard:ANSI/A
10、SNT CP-189 ASNT Standard for Qualification andCertification of Nondestructive Testing Personnel32.4 Aerospace Industries Association Document:NAS-410 NAS Certification and Qualification of Nonde-structive Test Personnel42.5 ISO Standard5ISO 9712 Non-destructive testing Qualification and cer-tificati
11、on of NDT personnel3. Terminology3.1 DefinitionsFor definitions of terms used in this guide,see Terminology E1316.4. Basis for Application4.1 Contractual AgreementThe using parties shall agreeon the applicable procedural requirements, as listed herein,prior to the examination of any material.1This g
12、uide is under the jurisdiction of ASTM Committee E07 on Nondestruc-tive Testing and is the direct responsibility of Subcommittee E07.06 on UltrasonicMethod.Current edition approved Dec. 1, 2013. Published February 2014. Originallyapproved in 1997. Last previous edition approved in 2008 as E1901 - 08
13、. DOI:10.1520/E1901-13.2For 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 website.3Available from American National Stan
14、dards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.4Available from Aerospace Industries Association of America, Inc. (AIA), 1000Wilson Blvd., Suite 1700,Arlington, VA22209-3928, http:/www.aia-aerospace.org.5Available from International Organization for Standardi
15、zation (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 States14.1.1 Materials, sizes, a
16、nd shapes examined,4.1.2 Stage of manufacture when examined (time of test),4.1.3 Surface finish requirements,4.1.4 Minimum equipment requirements, as in Table 1herein,4.1.5 Search unit size, frequency and type,4.1.6 Couplant,4.1.7 Automated turning, fixturing or scanning, or both, asapplicable,4.1.8
17、 Type of reference block standards including surfacecurvature,4.1.9 Standardization details, including attenuation compen-sation and DAC techniques,4.1.10 The surfaces to be examined and the scanning path,4.1.11 Acceptance standards,4.1.12 Personnel certification level, and4.1.13 Instrument characte
18、ristics.4.2 Written ProcedureUltrasonic examinations performedin accordance with this guide shall be detailed in a writtenprocedure. Documentation of procedure qualification shall bemaintained by the preparer. Procedures shall be sufficientlydetailed so that other qualified examiners may duplicate t
19、heexamination and obtain equivalent results.4.3 Personnel QualificationsPersonnel performing ultra-sonic examinations in accordance with this guide shall bequalified in accordance with SNT-TC-1A, ANSI/ASNT CP-189, NAS-410, ISO 9712, or MIL-STD-410, and certified bythe employer or certifying agency,
20、as applicable. Other equiva-lent qualification documents may be used when specified in thecontract or purchase order. The applicable revision shall be thelatest unless otherwise specified in the contractual agreementbetween parties.NOTE 1MIL-STD-410 is canceled and has been replaced withNAS-410, how
21、ever, it may be used with agreement between contractingparties.4.4 If specified in the contractual agreement, NDT agenciesshall be qualified and evaluated as described in Practice E543.5. Summary of Guide5.1 This guide describes a means for obtaining an evalua-tion of discontinuities in materials by
22、 contact examinationusing longitudinal waves. Equipment, reference standards,examination and evaluation procedures, and documentation ofresults are described in detail.6. Significance and Use6.1 This guide provides procedures for the application ofcontact straight-beam examination for the detection
23、and quan-titative evaluation of discontinuities in materials.6.2 Although not all requirements of this guide can beapplied universally to all inspections, situations, and materials,it does provide basis for establishing contractual criteriabetween the users, and may be used as a general guide forpre
24、paring detailed specifications for a particular application.6.3 This guide is directed towards the evaluation of discon-tinuities detectable with the beam normal to the entry surface.If discontinuities or other orientations are of concern, alternatescanning techniques are required.7. Apparatus7.1 Ap
25、paratus shall include the following:7.1.1 Electronic EquipmentThe electronic equipmentshall be capable of producing and processing electronic signalsat frequencies in the range of the search unit frequencies beingused. The equipment and its display shall provide characteris-tics as listed in Table 1
26、, that are suitable for the specificapplication at the specified frequency, as determined in accor-dance with the procedures and tolerances described in PracticeE317. The equipment, including the search unit, shall becapable of producing echo amplitudes of at least 60 % of fullscreen height from the
27、 reference reflector required for theexamination, with the material noise level, from front to backsurface not exceeding 20 % of full screen height.Alternatively,if these conditions can be met at one half the part thickness, thepart may be inspected from both sides.NOTE 2The using parties should agr
28、ee on the minimum instrumentcharacteristics prior to conducting an examination.7.1.2 Voltage RegulatorIf fluctuations in line voltagecause indication amplitude variations exceeding 612 dB, avoltage regulator shall be required on the power source. Thisrequirement is not applicable to battery-operated
29、 units.7.1.3 Search UnitsThe search unit selected shall be ca-pable of transmitting and receiving ultrasound at the requiredfrequencies and energy levels necessary for discontinuitydetection in the material being examined. The search unitsshall be of the contact type. Only longitudinal wave, straigh
30、tbeam, non-focused search units should be used. Dual elementsearch units may provide better near-surface resolution anddetection of small discontinuities. Generally, round or rectan-gular search units are used for examination whereas roundsearch units with symmetrical sound beam patterns are used fo
31、revaluation. Typical search unit sizes range from18 in. (3.2 mm)in diameter to 1-18 in. (28.6 mm) in diameter with other sizesand shapes available for special applications. Search units maybe fitted with contoured shoes to enhance coupling with curvedsurfaces.7.1.4 Alarm(s)For the examination of par
32、ts with regularshape and parallel surfaces such as machined cylinders, rounds,TABLE 1 Minimum Equipment Requirements (Longitudinal Wave)Instrument CharacteristicsUltrasonic TestFrequency MHZ(Record)Vertical limit, in. (mm) or percentof full screen heightUpper vertical linearity limit in. (mm)or perc
33、ent of full screen heightLower vertical linearity limit in. (mm)or percent of full screen heightUltrasonic sensitivity, hole size,64 ths, distance, in (mm)Entry surface resolution, in. (mm)Back surface resolution in. (mm)Horizontal limit, in. (mm) orpercent of full screen widthHorizontal linearity r
34、ange, in. (mm)or percent of full screen widthE1901 132bars, forgings, etc. an audible/visual alarm may be used inconjunction with visual monitoring of the display for thedetection of discontinuities or for the monitoring and detectionof loss of back surface reflection, or both. The alarm should bead
35、justable to allow triggering at commonly required indicationamplitudes, back-echo heights, and depths. During examina-tion the audible visual alarm shall be easily detectable by theoperator.7.1.4.1 When reduction in the amplitude of back-surfacereflection is monitored simultaneously with the detecti
36、on oflower amplitude signals from small, discrete discontinuities,two separate gate/alarm systems are required. The negativeslaved alarm system may also provide for a significantly lowerreceiver gain at the gated depth to avoid back-echo saturation.See 10.1 and 10.4.7.1.4.2 For some applications it
37、may be advantageous toutilize a flaw gate system in which the echo-amplitude alarmlevel can be varied as a function of target depth. Refer todistance/amplitude gate (DAG) in 9.3.2.1.7.2 CouplantAcouplant, usually a liquid or semi-liquid, isrequired between the face of the search unit and the examina
38、-tion surface to permit transmittance of ultrasound from thesearch unit into the material under examination. Typicalcouplants include water, cellulose gel, oil and grease. Corro-sion inhibitors or wetting agents or both may be used.Couplants selected must not be detrimental to the product orthe proc
39、ess. The same couplant used for standardization shallbe used for the examination. During the performance of acontact ultrasonic examination, the couplant layer betweensearch unit and examination material must be maintained suchthat the contact area is held constant while maintainingadequate couplant
40、 thickness. Lack of couplant that will reducethe effective contact area, or excess couplant, will reduce theamount of energy transferred between the search unit and theexamination surface. These couplant variations, in turn, resultin examination sensitivity variations.7.2.1 The couplant should be se
41、lected such 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 and will result in somedeterioration of near-surface discontinuity detection. The tem-perature of the material surface ca
42、n change the couplantsviscosity as in the case of oil and grease. See Table 2 for thesuggested viscosity of oil couplants for given surface rough-nesses.7.2.2 At elevated temperatures as conditions warrant, heat-resistant coupling materials such as silicone oils, gels, orgreases should be used. Furt
43、her, intermittent contact of thesearch unit with the part surface or auxiliary cooling of thesearch unit may be necessary to avoid temperature changes thataffect the ultrasonic characteristics of the search unit.At highertemperatures, certain couplants based on inorganic salts orthermoplastic organi
44、c materials, high-temperature delay mate-rials (shoes) and search units that are not affected by hightemperatures may be required.7.2.3 Where constant coupling over large areas is required,as in automated examination, or where severe changes insurface roughness are found, other methods of coupling s
45、uch asliquid gap coupling will usually provide a better examination.In this case, the search unit does not contact the examinationsurface, but is separated by a distance of about 0.02 in. (0.5mm) filled with couplant. Liquid flowing through the searchunit mechanism fills the gap. The flowing liquid
46、provides thecoupling path and has the additional advantage of cooling thesearch unit if the examination surface is warm.7.2.4 Another means of direct contact coupling is providedby the wheel search unit. The search unit is mounted at thecorrect angle to a stationary axle about which rotates aliquid-
47、filled flexible tire. A minimum amount of couplantprovides for ultrasonic transmission into the examinationsurface since the elastic tire material is in rolling contact andconforms closely to the surface.7.3 Reference StandardsThe production item itself maybe an adequate standard using the height of
48、 the back-wall echofor reference. For more quantitative information, charts such asDistance Gain Size (DGS, also known as AVG in Germantranslation), representing distance-amplitude relationships ofknown reflector sizes for a particular search unit, frequencyand material may be used for standardizati
49、on and evaluation ofdiscontinuities.7.3.1 Reference BlocksUltrasonic reference blocks, oftencalled test blocks, are used to standardize the ultrasonicequipment and to evaluate the indications received fromdiscontinuities within the part. The ultrasonic characteristics ofthe reference blocks such as attenuation, noise level, surfacecondition, and sound velocity, should be similar to the materialto be examined. Standardization verifies that the instrumentsearch unit is performing as required and establishes a detec-tion level for discontinuities.7.3.2 Flat BlocksT
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