1、Designation: A388/A388M 11Used 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, the
2、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 fo
3、rgings 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 examinati
4、on 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 in
5、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 spe
6、cification 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 all
7、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 Specificati
8、on for Vacuum-Treated Steel Forg-ings for Generator RotorsA745/A745M Practice for Ultrasonic Examination of Aus-tenitic Steel ForgingsE317 Practice for Evaluating Performance Characteristicsof Ultrasonic Pulse-Echo Testing Instruments and Systemswithout the Use of Electronic Measurement InstrumentsE
9、428 Practice for Fabrication and Control of Metal, Otherthan Aluminum, Reference Blocks Used in UltrasonicTestingE1065 Guide for Evaluating Characteristics of UltrasonicSearch Units2.2 Other Document:Recommended Practice for Nondestructive Personnel Quali-fication and Certification SNT-TC-1A, (1988
10、or later)43. 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 showinga decrease in amplitude as the search unit is moved in anydirection fro
11、m 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. 25 mm or twice the major dimension of the transducer,whichever is greater, and
12、 do not travel.3.1.4 traveling indications, ninductions whose 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 th
13、e order or specification for inspection purposeswhere the acceptance 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 req
14、uirements.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 approved April 1, 2011. Published May 2011. Originallyapproved in 1955. Last previ
15、ous edition approved in 2010 as A388/A388M 10.DOI: 10.1520/A0388_A0388M-11.2For ASME Boiler and Pressure Vessel Code applications see related Specifi-cation SA-388/SA-388M in Section II of that Code.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service
16、 at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.4Available from the American Society for Nondestructive Testing, 1711 Arlin-gate Ln., P.O. Box 28518, Columbus, OH 432280518.1*A Summary of Changes section appear
17、s at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5. Ordering Information5.1 When this practice is to be applied to an inquiry,contract, or order, the purchaser shall so state and shall alsofurnish the foll
18、owing 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 (Vee- or rectangular-notch),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
19、.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, 10.1, 10.2, and 12.2.6. Apparatus6.1 Electronic ApparatusAn ultrasonic, pulsed, reflectiontype of instrument shall be used for th
20、is examination. Thesystem shall have a minimum capability for examining atfrequencies from 1 to 5 MHz. On examining austeniticstainless forgings the system shall have the capabilities forexamining at frequencies down to 0.4 MHz.6.1.1 Apparatus Qualification and CalibrationBasicqualification of the u
21、ltrasonic 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 last calibration and the date of the next requiredcalibration shall be displayed on the test equipment.6.1.2 The ultrasonic instr
22、ument 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 the screen presentation of amplitude. Instrumentlinearity shall be verified in accordance with the intent ofPractice E317. Any set
23、 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 an attenuator(accurate over its useful range to 610 % (+1 dB) of theamplitude ratio) which will allow measurement of indicationsbe
24、yond 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 dimensions shall be used forstraight-beam scanning (see 9.2); and search units with12 in.13 mm minimum to 1 in. 25 mm maximum dime
25、nsionsshall 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 andpinpointing indications.6.3 Couplants, having good wetting characteristics such asSAE No. 20 or No. 30 motor oil, glycerin, pine
26、 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, containing flat-bottom holes may beused for calibration of equipment in accordance with 6.1.2 andmay be used to establish recording leve
27、ls 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 establish recordinglevels for straight beam examination, when so specified by theorder or contract. The DGS scale range must be
28、selected toinclude the full thickness cross-section of the forging to beexamined. An example of a DGS overlay is found in AppendixX3.6.5.1 As an alternative to using DGS overlays, an ultrasonicinstrument having integral decibel gain or attenuator controlsin combination with a specifically paired tra
29、nsducer and DGSdiagram may be used to evaluate ultrasonic indications.7. Personnel Requirements7.1 Personnel performing the ultrasonic examinations to thispractice shall be qualified and certified in accordance with awritten procedure conforming to Recommended Practice No.SNT-TC-1A (1988 or later) o
30、r another national standard that isacceptable to both the purchaser and the supplier.8. Preparation of Forging for Ultrasonic Examination8.1 Unless otherwise specified in the order or contract, theforging shall be machined to provide cylindrical surfaces forradial examination in the case of round fo
31、rgings; the ends ofthe forgings shall be machined perpendicular to the axis of theforging for the axial examination. Faces of disk and rectangularforgings shall be machined flat and parallel to one another.8.2 The surface roughness of exterior finishes shall notexceed 250 in. 6 m unless otherwise sh
32、own on the forgingdrawing or stated in the order or the contract.8.3 The surfaces 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
33、 examination. Because of radii at changeof sections and other local configurations, it may be impossibleto examine some sections of a forging.9.1.2 Perform the ultrasonic examination after heat treat-ment for mechanical properties (exclusive of stress-relieftreatments) but prior to drilling holes, c
34、utting keyways, tapers,grooves, or machining sections to contour. 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
35、cases, reexamine the forgingultrasonically as completely as 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 auto
36、mated scanning, adjust scanning speed orinstrument repetition 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 calibra
37、tion was made.A388/A388M 1129.1.6 If possible, scan all sections of forgings 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
38、 radiallyusing a straight-beam technique. When practicable, also exam-ine 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 c
39、omparable equipment, search units, frequency,and couplant.9.1.11 Forgings 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 examinat
40、ion use a nominal 214-MHz search unit whenever practicable; however, 1 MHz 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 frequencie
41、s may be used ifdesirable for better resolution, penetrability, or detectability 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-Reflecti
42、on Cali-bration Applicable to Forgings with Parallel Entry and BackSurfaces)With the attenuator set at an appropriate level, forexample 5 to 1 or 14 dB, adjust the instrument controls toobtain a back reflection approximately 75 % of the full-screenheight from the opposite side of the forging. Scan t
43、he forgingat the maximum amplification setting of the attenuator (attenu-ator set at 1 to 1). Carry out the evaluation of discontinuitieswith the gain control set at the reference level. Recalibration isrequired for significant changes in section thickness or diam-eter.NOTE 1High sensitivity levels
44、are not usually employed when in-specting austenitic steel forgings due to attendant high level of “noise” or“hash” caused by coarse 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 exam
45、ined. Adjust theinstrument controls to obtain the required signal amplitudefrom the flat-bottom hole in the specified reference block.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 t
46、he forging.NOTE 2When flat-surfaced reference block calibration is specified,adjust the amplitude of indication from the reference 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 matche
47、s the transducer size and frequency. Accuracyof the overlay can be verified by reference blocks andprocedures outlined in Practice E317. Overlays are to beserialized to match the ultrasonic transducer and pulse echotesting system that they are to be utilized with.9.2.2.4 Choose the appropriate DGS s
48、cale for the cross-sectional thickness of the forging to be examined. Insert theoverlay over the CRT screen, ensuring the DGS scale base linecoincides with the sweep line of the CRT screen. Place theprobe on the forging, adjust the gain to make the first back-wallecho appear clearly on CRT screen. U
49、sing the Delay andSweep control, shift the screen pattern so that the leading edgeof the initial pulse is on zero of the DGS scale and theback-wall echo is on the DGS scale value corresponding to thethickness of the forging. Adjust the gain so the forgingback-wall echo matches the height of the DGS reference slopewithin 61 Db. Once adjusted, increase the gain by the Dbshown on the DGS scale for the reference slope. Instrument isnow calibrated and flaw sizes that can be reliably detected canbe directly read from the CRT screen. These flaw size
