1、Designation: A388/A388M 16a Used in USNRC-RDT standardsStandard Practice forUltrasonic Examination of Steel Forgings1This standard is issued under the fixed designation A388/A388M; the number immediately following the designation indicates the yearof original adoption or, in the case of revision, th
2、e year of last revision. A number in parentheses indicates the year of last reapproval.A superscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This practice2covers the examination procedures for thecontact, pulse-echo ultrasonic examination of steel
3、forgings bythe straight and angle-beam techniques. The straight beamtechniques include utilization of the DGS (Distance Gain-Size)method. See Appendix X3.1.2 This practice is to be used whenever the inquiry,contract, order, or specification states that forgings are to besubject to ultrasonic examina
4、tion in accordance with PracticeA388/A388M.1.3 Supplementary requirements of an optional nature areprovided for use at the option of the purchaser. The supple-mentary requirements shall apply only when specified indi-vidually by the purchaser in the purchase order or contract.1.4 The values stated i
5、n either SI units or inch-pound unitsare to be regarded separately as standard. The values stated ineach system may not be exact equivalents; therefore, eachsystem shall be used independently of the other. Combiningvalues from the two systems may result in non-conformancewith the standard.1.5 This s
6、pecification and the applicable material specifica-tions are expressed in both inch-pound units and SI units.However, unless the order specifies the applicable “M” speci-fication designation SI units, the material shall be furnishedto inch-pound units.1.6 This standard does not purport to address al
7、l 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 determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:3A469/A469M Specifica
8、tion for Vacuum-Treated Steel Forg-ings for Generator RotorsA745/A745M Practice for Ultrasonic Examination of Aus-tenitic Steel ForgingsA788/A788M Specification for Steel Forgings, General Re-quirementsE317 Practice for Evaluating Performance Characteristics ofUltrasonic Pulse-Echo Testing Instrumen
9、ts and Systemswithout the Use of Electronic Measurement InstrumentsE428 Practice for Fabrication and Control of Metal, Otherthan Aluminum, Reference Blocks Used in UltrasonicTestingE1065/E1065M Practice for Evaluating Characteristics ofUltrasonic Search Units2.2 Other Document:4Recommended Practice
10、for Nondestructive Personnel Quali-fication and Certification SNT-TC-1A, (1988 or later)3. Terminology3.1 Definitions:3.1.1 indication levels (clusters), nfive or more indica-tions in a volume representing a 2-in. 50-mm or smaller cubein the forging.3.1.2 individual indications, nsingle indications
11、showinga decrease in amplitude as the search unit is moved in anydirection from the position of maximum amplitude and whichare too small to be considered traveling or planar.3.1.3 planar indications, nindications shall be consideredcontinuous over a plane if they have a major axis greater than1 in.
12、25 mm or twice the major dimension of the transducer,whichever is greater, and do not travel.1This practice is under the jurisdiction of ASTM Committee A01 on Steel,Stainless Steel and Related Alloys and is the direct responsibility of SubcommitteeA01.06 on Steel Forgings and Billets.Current edition
13、 approved Sept. 1, 2016. Published September 2016. Originallyapproved in 1955. Last previous edition approved in 2016 as A388/A388M 16.DOI: 10.1520/A0388_A0388M-16A.2For ASME Boiler and Pressure Vessel Code applications see related Specifi-cation SA-388/SA-388M in Section II of that Code.3For refere
14、nced 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.4Available fromAmerican Society for Nondestructive Testing (ASNT), P.O.
15、Box28518, 1711 Arlingate Ln., Columbus, OH 43228-0518, http:/www.asnt.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 States13.1.4 traveling indications, ninductions whose
16、leadingedge moves a distance equivalent to 1 in. 25 mm or more ofmetal depth with movement of the transducer over the surfaceof the forging.4. Significance and Use4.1 This practice shall be used when ultrasonic inspection isrequired by the order or specification for inspection purposeswhere the acce
17、ptance of the forging is based on limitations ofthe number, amplitude, or location of discontinuities, or acombination thereof, which give rise to ultrasonic indications.4.2 The ultrasonic quality level shall be clearly stated asorder requirements.5. Ordering Information5.1 When this practice is to
18、be applied to an inquiry,contract, or order, the purchaser shall so state and shall alsofurnish the following information:5.1.1 Designation number (including year date),5.1.2 Method of establishing the sensitivity in accordancewith 9.2.2 and 9.3.3 (DGS (Distance Gain Size), Vee- orrectangular-notch)
19、,5.1.2.1 The diameter and test metal distance of the flat-bottom hole and the material of the reference block inaccordance with 9.2.2.2,5.1.3 Quality level for the entire forging or portions thereofin accordance with 12.3, and5.1.4 Any options in accordance with 1.5, 6.4, 6.5, 7.1, 8.1,8.2, 9.1.11,
20、10.1, 10.2, and 12.2.6. Apparatus6.1 Electronic ApparatusAn ultrasonic, pulsed, reflectiontype of instrument shall be used for this examination. Thesystem shall have a minimum capability for examining atfrequencies from 1 to 5 MHz. On examining austeniticstainless forgings the system shall have the
21、capabilities forexamining at frequencies down to 0.4 MHz.6.1.1 Apparatus Qualification and CalibrationBasicqualification of the ultrasonic test instrument shall be per-formed at intervals not to exceed 12 months or whenevermaintenance is performed that affects the equipment function.The date of the
22、last calibration and the date of the next requiredcalibration shall be displayed on the test equipment.6.1.2 The ultrasonic instrument shall provide linear presen-tation (within 5 %) for at least 75 % of the screen height(sweep line to top of screen). The 5 % linearity referred to isdescriptive of t
23、he screen presentation of amplitude. Instrumentlinearity shall be verified in accordance with the intent ofPractice E317. Any set of blocks processed in accordance withPractice E317 or E428 may be used to establish the specified65 % instrument linearity.6.1.3 The electronic apparatus shall contain a
24、n attenuator(accurate over its useful range to 610 % (+1 dB) of theamplitude ratio) which will allow measurement of indicationsbeyond the linear range of the instrument.6.2 Search Units, having a transducer with a maximumactive area of 1 in.2650 mm2 with34 in. 20 mm minimumto 118 in. 30 mm maximum d
25、imensions shall be used forstraight-beam scanning (see 9.2); and search units with12 in.13 mm minimum to 1 in. 25 mm maximum dimensionsshall be used for angle-beam scanning (see 9.3).6.2.1 Transducers shall be utilized at their rated frequencies.6.2.2 Other search units may be used for evaluating an
26、dpinpointing indications.6.3 Couplants, having good wetting characteristics such asSAE No. 20 or No. 30 motor oil, glycerin, pine oil, or watershall be used. Couplants may not be comparable to one anotherand the same couplant shall be used for calibration andexamination.6.4 Reference Blocks, contain
27、ing flat-bottom holes may beused for calibration of equipment in accordance with 6.1.2 andmay be used to establish recording levels for straight-beamexamination when so specified by the order or contract.6.5 DGS Scales, matched to the ultrasonic test unit andtransducer to be utilized, may be used to
28、 establish recordinglevels for straight or angle beam examination, when sospecified by the order or contract. The DGS scale range mustbe selected to include the full thickness cross-section of theforging to be examined.An example of a DGS overlay is foundin Appendix X3.6.5.1 As an alternative to usi
29、ng DGS overlays, an ultrasonicinstrument having DGS software, integral decibel gain orattenuator controls in combination with a specifically pairedtransducer and DGS diagram may be used to evaluate ultra-sonic indications.7. Personnel Requirements7.1 Personnel performing the ultrasonic examinations
30、to thispractice shall be qualified and certified in accordance with awritten procedure conforming to Recommended Practice No.SNT-TC-1A (1988 or later) or another national standard that isacceptable to both the purchaser and the supplier.8. Preparation of Forging for Ultrasonic Examination8.1 Unless
31、otherwise specified in the order or contract, theforging shall be machined to provide cylindrical surfaces forradial examination in the case of round forgings; the ends ofthe forgings shall be machined perpendicular to the axis of theforging for the axial examination. Faces of disk and rectangularfo
32、rgings shall be machined flat and parallel to one another.8.2 The surface roughness of exterior finishes shall notexceed 250 in. 6 m where the definition for surface finishis as per Specification A788/A788M unless otherwise shownon the forging drawing or stated in the order or the contract.8.3 The s
33、urfaces of the forging to be examined shall be freeof extraneous material such as loose scale, paint, dirt, and soforth.9. Procedure9.1 General:9.1.1 As far as practicable, subject the entire volume of theforging to ultrasonic examination. Because of radii at changeof sections and other local config
34、urations, it may be impossibleto examine some sections of a forging.A388/A388M 16a29.1.2 Perform the ultrasonic examination after heat treat-ment for mechanical properties (exclusive of stress-relieftreatments) but prior to drilling holes, cutting keyways, tapers,grooves, or machining sections to co
35、ntour. If the configurationof the forging required for the treatment for mechanicalproperties prohibits a subsequent complete examination of theforging, it shall be permissible to examine prior to treatment formechanical properties. In such cases, reexamine the forgingultrasonically as completely as
36、 possible after heat treatment.9.1.3 To ensure complete coverage of the forging volume,index the search unit with at least 15 % overlap with each pass.9.1.4 For manual scanning, do not exceed a scanning rate of6 in./s 150 mm/s.9.1.5 For automated scanning, adjust scanning speed orinstrument repetiti
37、on rate, or both, to permit detection of thesmallest discontinuities referenced in the specification and toallow the recording or signaling device to function. At no timeshall the scanning speed exceed the speed at which anacceptable calibration was made.9.1.6 If possible, scan all sections of forgi
38、ngs in twoperpendicular directions.9.1.7 Scan disk forgings using a straight beam techniquefrom at least one flat face and radially from the circumference,whenever practicable.9.1.8 Scan cylindrical sections and hollow forgings radiallyusing a straight-beam technique. When practicable, also exam-ine
39、 the forging in the axial direction.9.1.9 In addition, examine hollow forgings by angle-beamtechnique from the outside diameter surface as required in9.3.1.9.1.10 In rechecking or reevaluation by manufacturer orpurchaser, use comparable equipment, search units, frequency,and couplant.9.1.11 Forgings
40、 may be examined either stationary or whilerotating in a lathe or on rollers. If not specified by thepurchaser, either method may be used at the manufacturersoption.9.2 Straight-Beam Examination:9.2.1 For straight-beam examination use a nominal 214-MHz search unit whenever practicable; however, 1 MH
41、z is thepreferred frequency for coarse grained austenitic materials andlong testing distances. In many instances on examining coarsegrained austenitic materials it may be necessary to use afrequency of 0.4 MHz. Other frequencies may be used ifdesirable for better resolution, penetrability, or detect
42、ability offlaws.9.2.2 Establish the instrument sensitivity by either thereflection, reference-block technique, or DGS method (seeAppendix X3 for an explanation of the DGS method).9.2.2.1 Back-Reflection Technique (Back-Reflection Cali-bration Applicable to Forgings with Parallel Entry and BackSurfac
43、es)Use the back reflection from the opposite side ofthe part as a calibration standard to set the sensitivity for thetest. The two surfaces (entry surface and the reflecting surface)must be parallel to each other. Place the transducer in an areaof the forging, when possible, so that the geometry wil
44、l nothave an effect on the beam spread. Increase the gain to obtaina 75 % full screen height back reflection, increase the gain byup to an additional 20 dB (10:1). If no indications are present(indication free) return the gain to the original dB setting of the75 % full screen height (1:1), this will
45、 be the reference level.Scanning should be done at a level greater than the referencelevel, such as 6 dB (2:1). During the scanning, the backreflection shall be monitored for any significant loss ofamplitude not attributed to the geometry. Carry out the evalu-ation of discontinuities with the gain c
46、ontrol set at the referencelevel (75 % full screen height). Recalibration is required forsignificant changes in section thickness or diameter.NOTE 1High sensitivity levels are not usually employed wheninspecting austenitic steel forgings due to attendant high level of “noise”or “hash” caused by coar
47、se grain structure.9.2.2.2 Reference-Block CalibrationThe test surfaceroughness on the calibration standard shall be comparable to,but no better than, the item to be examined. Adjust theinstrument controls to obtain the required signal amplitudefrom the flat-bottom hole in the specified reference bl
48、ock.Utilize the attenuator in order to set up on amplitudes largerthan the vertical linearity of the instrument. In those cases,remove the attenuation prior to scanning the forging.NOTE 2When flat-surfaced reference block calibration is specified,adjust the amplitude of indication from the reference
49、 block or blocks tocompensate for examination surface curvature (an example is given inAppendix X1).9.2.2.3 DGS CalibrationPrior to use, verify that the DGSoverlay or electronic DGS curve matches the transducer sizeand frequency. Accuracy of the overlay can be verified byreference blocks and procedures outlined in Practice E317.Overlays are to be serialized to match the ultrasonic transducerand pulse echo testing system that they are to be utilized with.Instruments with electronic DGS must use the specified ultra-sonic transducer for that ele
