1、Designation: E 1901 97 (Reapproved 2003)Standard 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 adopt
2、ion or, in the case of revision, 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.1. Scope1.1 This guide covers procedures for the contact ultrasonicexamination of bu
3、lk materials or parts 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
4、 that may be used for 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 E 114 by providingmore detailed procedures
5、for the selection and calibration ofthe inspection system and for evaluation of the indicationsobtained.1.3 The values stated in inch-pound units are to be regardedas the standard. The SI units given in brackets are forinformation only.1.4 This guide does not purport to address all of the safetyconc
6、erns, 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 ASTM Standards:E 114 Practice for Ultrasonic Pulse-Echo St
7、raight-BeamExamination by the Contact Method2E 127 Practice for Fabricating and Checking AluminumAlloy Ultrasonic Standard Reference Blocks2E 317 Practice for Evaluating Performance Characteristicsof Ultrasonic Pulse-Echo Examination Instruments andSystems without the Use of Electronic Measurement I
8、n-struments2E 428 Practice for Fabrication and Control of Steel Refer-ence Blocks Used in Ultrasonic Inspection2E 543 Practice for Agencies Performing NondestructiveTesting2E 1158 Guide for Material Selection and Fabrication ofReference Blocks for the Pulsed Longitudinal Wave Ultra-sonic Examination
9、s of Metal and Metal Alloy ProductionMaterials2E 1316 Terminology for Nondestructive Examinations22.2 ASNT Standard:SNT-TC-1A Recommended Practice for Personnel Qualifi-cation and Certification in Nondestructive Testing Person-nel32.3 ANSI/ASNT Standard:CP-189 ASNT Standard for Qualification and Cer
10、tificationof Nondestructive Testing Personnel32.4 Military Standard:MIL-STD-410 Nondestructive Testing Personnel Qualifica-tion and Certification43. Terminology3.1 DefinitionsFor definitions of terms used in this guide,see Terminology E 1316.4. Basis for Application4.1 Contractual AgreementThe using
11、 parties shall agreeon the applicable procedural requirements, as listed herein,prior to the examination of any material.4.1.1 Materials, sizes, and 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 T
12、able 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 surfacecurvature,4.1.9 Standardization details, including attenuation compen-sation and DAC techniques,1This
13、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 edition approved July 10, 2003. Published September 2003. Originallyapproved in 1997. Last previous edition approved in 1997 as E 1901
14、- 97.2Annual Book of ASTM Standards, Vol 03.03.3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036.4Available from Standardization Documents Order Deck, Bldg. 4 Section D, 700Robbins Ave., Philadelphia, PA 191115094, Attn: NPODS.1Copyright ASTM
15、International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.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 examinati
16、ons 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 P
17、ersonnel QualificationsPersonnel performing ultra-sonic examinations in accordance with this guide shall bequalified in accordance with a nationally recognized NDTpersonnel qualification practice or standard; such as SNT-TC-1A, ANSI/ASNT CP-189, MIL-STD-410, or a similar docu-ment. The practice or s
18、tandard used and its applicable revisionshall be specified in the contractual agreement between theusing parties.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 obtainin
19、g an evalua-tion of discontinuities in materials by 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 ofc
20、ontact straight-beam examination for the detection 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 t
21、he users, and may be used as a general guide forpreparing 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, alternate
22、scanning techniques are required.7. Apparatus7.1 Apparatus 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
23、shall provide characteris-tics as listed in Table 1, that are suitable for the specificapplication at the specified 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 ampli
24、tudes of at least 60 % of fullscreen height from the 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 inspect
25、ed from both sides.NOTE 1The using parties should agree 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.
26、Thisrequirement is not applicable to battery-operated 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
27、 of the contact type. Only longitudinal wave, straightbeam, 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 u
28、nits with symmetrical sound beam patterns are used forevaluation. Typical search unit sizes range from18 in. 3.2 mmin 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 curved
29、surfaces.7.1.4 Alarm(s)For the examination of parts with regularshape and parallel surfaces such as machined 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 de
30、tectionof loss of back surface reflection, or both. The alarm should beadjustable 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 amplitu
31、de of back-surfacereflection is monitored simultaneously with the detection 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
32、 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 which the echo-amplitude alarmlevel can be varied as a function of target depth. Refer todistance/amplitude gate (DAG) in 9.3.2.1.TABLE 1 Minimum Equipment Requirements (Longi
33、tudinal Wave)Instrument CharacteristicsUltrasonic TestFrequency MHZ(Record)Vertical limit, in. mm or percentof full screen heightUpper vertical linearity limit in. mmor percent of full screen heightLower vertical linearity limit in. mmor percent of full screen heightUltrasonic sensitivity, hole size
34、,64 ths, distance, in mmEntry surface resolution, in. mmBack surface resolution in. mmHorizontal limit, in. mm orpercent of full screen widthHorizontal linearity range, in. mmor percent of full screen widthE 1901 97 (2003)27.2 CouplantA couplant, usually a liquid or semi-liquid,is required between t
35、he face of the search unit and theexamination surface to permit transmittance of ultrasound fromthe 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
36、be detrimental to the product orthe process. 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 con
37、stant while maintainingadequate couplant 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 va
38、riations.7.2.1 The couplant should be selected 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
39、 tem-perature of the material surface can 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 oi
40、ls, gels, orgreases should be used. Further, 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
41、on inorganic salts orthermoplastic organic 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 roughne
42、ss are found, other methods of coupling such 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 mecha
43、nism fills the gap. The flowing liquid 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 stati
44、onary axle about which rotates aliquid-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 a
45、n adequate standard using the height of the back-wall echofor reference. For more quantitative information, charts such as(AVG-DGS) representing distance-amplitude relationships ofknown reflector sizes for a particular search unit, frequencyand material may be used for standardization and evaluation
46、 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, nois
47、e 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 bloc
48、k are area-amplitude set, containing blocks withthe same material path and various sizes of reference reflectors;distance-amplitude set, containing blocks with one size refer-ence reflector at various material distances; and a combinationincluding both area-amplitude and distance-amplitude blocksin
49、one set. These sets are described in Practices E 127 andE 428.7.3.3 Curved SurfacesReference blocks with flat surfacesmay be used for establishing gain settings for examinations onconcave test surfaces and convex surfaces with radii ofcurvature 4 in. 101.6 mm or greater. For convex surfaces withradii of curvature less than 4 in. 101.6 mm it is recommendedthat reference blocks with approximately the same nominalradius of curvature shall be used. Guide E 1158 illustratestypical curved entry surface blocks.7.4 Reference ReflectorsFlat-bottomed h
