1、Designation: E 1901 08Standard Guide forDetection and Evaluation of Discontinuities by ContactPulse-Echo Straight-Beam Ultrasonic Methods1This standard is issued under the fixed designation E 1901; the number immediately following the designation indicates the year oforiginal adoption or, in the cas
2、e 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. Scope1.1 This guide covers procedures for the contact ultrasonicexamination of bulk materials or par
3、ts 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 f
4、or detecting discon-tinuities, locating depth and distance from a point of referenceand for making a relative or approximate evaluation of the sizeof discontinuities as compared to a reference standard.1.2 This guide complements Practice E114 by providingmore detailed procedures for the selection an
5、d calibration 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
6、.4 This 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 Document
7、s2.1 ASTM Standards:2E114 Practice for Ultrasonic Pulse-Echo Straight-BeamExamination by the Contact MethodE 127 Practice for Fabricating and Checking AluminumAlloy Ultrasonic Standard Reference BlocksE 317 Practice for Evaluating Performance Characteristicsof Ultrasonic Pulse-Echo Testing Instrumen
8、ts and Systemswithout the Use of Electronic Measurement InstrumentsE 428 Practice for Fabrication and Control of Metal, Otherthan Aluminum, Reference Blocks Used in UltrasonicTestingE 543 Specification for Agencies Performing Nondestruc-tive TestingE 1158 Guide for Material Selection and Fabrication
9、 ofReference Blocks for the Pulsed Longitudinal Wave Ultra-sonic Examination of Metal and Metal Alloy ProductionMaterialE 1316 Terminology for Nondestructive Examinations2.2 ASNT Standard:SNT-TC-1A Recommended Practice for Personnel Qualifi-cation and Certification in Nondestructive Testing Person-n
10、el32.3 ANSI/ASNT Standard:ANSI/ASNT CP-189 ASNT Standard for Qualification andCertification of Nondestructive Testing Personnel32.4 Military Standard:MIL-STD-410 Nondestructive Testing Personnel Qualifica-tion and Certification42.5 Aerospace Industries Association Document:NAS-410 NAS Certification
11、and Qualification of Nonde-structive Test Personnel53. Terminology3.1 DefinitionsFor definitions of terms used in this guide,see Terminology E 1316.4. Basis for Application4.1 Contractual AgreementThe using parties shall agreeon the applicable procedural requirements, as listed herein,prior to the e
12、xamination of any material.4.1.1 Materials, sizes, and shapes examined,4.1.2 Stage of manufacture when examined (time of test),1This guide is under the jurisdiction of ASTM Committee E07 on Nondestruc-tive Testing and is the direct responsibility of Subcommittee E07.06 on UltrasonicMethod.Current ed
13、ition approved July 1, 2008. Published July 2008. Originally approvedin 1997. Last previous edition approved in 2003 as E 1901 - 97(2003).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume
14、information, refer to the standards Document Summary page onthe ASTM website.3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.4Available from Standardization Documents Order Desk, DODSSP, Bldg. 4,Section D, 700 Robbins Ave
15、., Philadelphia, PA 19111-5098, http:/www.dodssp.daps.mil.5Available from Aerospace Industries Association of America, Inc. (AIA), 1000Wilson Blvd., Suite 1700,Arlington, VA22209-3928, http:/www.aia-aerospace.org.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, P
16、A 19428-2959, United States.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 Type of reference block standards including su
17、rfacecurvature,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 characteristics.4.2 Written ProcedureUltrasonic examina
18、tions 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 theexamination and obtain equivalent results.4.3
19、 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,orMIL-STD-410, and certified by the em-ployer or certifying agency, as applicable. Other equivalentqualification documents ma
20、y 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 with NAS-410, however, it may be used with agreement between contracting pa
21、rties.4.4 If specified in the contractual agreement, NDT agenciesshall be qualified and evaluated as described in Practice E 543.5. Summary of Guide5.1 This guide describes a means for obtaining an evalua-tion of discontinuities in materials by contact examinationusing longitudinal waves. Equipment,
22、 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 and quan-titative evaluation of discontinuities in mater
23、ials.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 forpreparing detailed specifications for a particular applicat
24、ion.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 Apparatus shall include the following:7.1.1 Electronic Equ
25、ipmentThe 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, that are suitable for the specificapplication at the s
26、pecified frequency, as determined in accor-dance with the procedures and tolerances described in PracticeE 317. The equipment, including the search unit, shall becapable of producing echo amplitudes of at least 60 % of fullscreen height from the reference reflector required for theexamination, with
27、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 agree on the minimum instrumentcharacteristics prior to co
28、nducting 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 units.7.1.3 Search UnitsThe search unit selected shall
29、 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, straightbeam, non-focused search units should be used. Dual el
30、ementsearch 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 forevaluation. Typical search unit sizes range from18 in.
31、 (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 parts with regularshape and parallel surfaces such as mach
32、ined cylinders, rounds,bars, 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 beadjustable to allow triggering at
33、 commonly required indicationTABLE 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 percent of full screen heightLower vertical linearity
34、 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 range, in. (mm)or percent of full screen widthE190
35、1082amplitudes, 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 detection oflower amplitude signals from small, discrete discon
36、tinuities,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 may be advantageous toutilize a flaw gate system in whic
37、h 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 CouplantA couplant, usually a liquid or semi-liquid,is required between the face of the search unit and theexamination surface to permit transmittance of ultrasound fromt
38、he search 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 process. The same couplant used for standardization shallbe u
39、sed 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 thickness. Lack of couplant that will reducethe effectiv
40、e 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 selected such that its viscosityis appropriate for the surf
41、ace 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 can change the couplantsviscosity as in the case of oil and
42、 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. Further, intermittent contact of thesearch unit with the part
43、 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 organic materials, high-temperature delay mate-rials (shoes) an
44、d 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 such asliquid gap coupling will usually provide a better e
45、xamination.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 provides thecoupling path and has the additional advantag
46、e 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-filled flexible tire. A minimum amount of couplantprovide
47、s 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 the back-wall echofor reference. For more quantitative i
48、nformation, charts such asDistance Gain Size (DGS, also known as AVG in Germantranslation), representing distance-amplitude relationships ofknown reflector (grain) sizes for a particular search unit,frequency and material may be used for standardization andevaluation of discontinuities.7.3.1 Referen
49、ce 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 BlocksThe three most commonly used sets ofreference block a
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