1、Designation: A 388/A 388M 07Used in USNRC-RDT standardsStandard Practice forUltrasonic Examination of Heavy Steel Forgings1This standard is issued under the fixed designationA 388/A 388M; the number immediately following the designation indicates the yearof original adoption or, in the case of revis
2、ion, the year of last revision. A number in parentheses indicates the year of last reapproval.A superscript epsilon (e) 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 o
3、f heavy steelforgings by the straight and angle-beam techniques. Thestraight beam techniques include utilization of the DGS (Dis-tance 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 ul
4、trasonic examination in accordance with PracticeA 388/A 388M.1.3 The values stated in 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. Combiningv
5、alues from the two systems may result in non-conformancewith the standard.1.4 This specification 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 sh
6、all be furnishedto inch-pound units.1.5 This standard does not purport to address all 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 limi
7、tations prior to use.2. Referenced Documents2.1 ASTM Standards:3A 469/A 469M Specification for Vacuum-Treated SteelForgings for Generator RotorsA 745/A 745M Practice for Ultrasonic Examination ofAus-tenitic Steel ForgingsE 317 Practice for Evaluating Performance Characteristicsof Ultrasonic Pulse-Ec
8、ho Testing Instruments and Systemswithout the Use of Electronic Measurement InstrumentsE 428 Practice for Fabrication and Control of Metal, Otherthan Aluminum Reference, Blocks Used in UltrasonicExaminationE 1065 Guide for Evaluating Characteristics of UltrasonicSearch Units2.2 ANSI Standard:B 46.1
9、Surface Texture42.3 Other Document:Recommended Practice for Nondestructive Personnel Quali-fication and Certification SNT-TC-1A, (1988 or later)53. 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 f
10、orging.3.1.2 individual indications, nsingle indications 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
11、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 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 trans
12、ducer over the surfaceof the forging.4. Ordering Information4.1 When this practice is to be applied to an inquiry,contract, or order, the purchaser shall so state and shall alsofurnish the following information:4.1.1 Designation number (including year date),4.1.2 Method of establishing the sensitivi
13、ty in accordancewith 8.2.2 and 8.3.3 (Vee- or rectangular-notch),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 March 1, 2007. Pub
14、lished March 2007. Originallyapproved in 1955. Last previous edition approved in 2005 as A 388/A 388M 05.2For 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, o
15、rcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.4Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036.5Available from the Ameri
16、can Society for Nondestructive Testing, 1711 Arlin-gate Ln., P.O. Box 28518, Columbus, OH 432280518.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4.1.2.1 The diamete
17、r and test metal distance of the flat-bottom hole and the material of the reference block inaccordance with 8.2.2.2,4.1.3 Quality level for the entire forging or portions thereofin accordance with 11.3, and4.1.4 Any options in accordance with 1.4, 5.4, 5.5, 6.1, 7.1,7.2, 8.1.11, 9.1, and 9.2.5. Appa
18、ratus5.1 An ultrasonic, pulsed, reflection type of instrument shallbe used for this examination. The system shall have a mini-mum capability for examining at frequencies from 1 to 5 MHz.On examining austenitic stainless forgings the system shallhave the capabilities for examining at frequencies down
19、 to 0.4MHz.5.1.1 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 the screen presentation of amplitude. Instrumentlinearity shall be verified in accordance wit
20、h the intent ofPractice E 317.Any set of blocks processed in accordance withPractice E 317 or E 428 may be used to establish the specified65 % instrument linearity.5.1.2 The electronic apparatus shall contain an attenuator(accurate over its useful range to 610 % (+1 dB) of theamplitude ratio) which
21、will allow measurement of indicationsbeyond the linear range of the instrument.5.2 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 8.2); and search units with12 in.13
22、 mm minimum to 1 in. 25 mm maximum dimensionsshall be used for angle-beam scanning (see 8.3).5.2.1 Transducers shall be utilized at their rated frequencies.5.2.2 Other search units may be used for evaluating andpinpointing indications.5.3 Couplants, having good wetting characteristics such asSAE No.
23、 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.5.4 Reference Blocks, containing flat-bottom holes may beused for calibration of equipment in accordance with 5.1.1 and
24、may be used to establish recording levels for straight-beamexamination when so specified by the order or contract.5.5 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
25、 contract. The DGS scale range must be selected toinclude the full thickness cross-section of the forging to beexamined. An example of a DGS overlay is found in AppendixX3.6. Personnel Requirements6.1 Personnel performing the ultrasonic examinations to thispractice shall be qualified and certified i
26、n 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.7. Preparation of Forging for Ultrasonic Examination7.1 Unless otherwise specified in the order or contract, thef
27、orging 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 rectangularforgings shall be machined flat and parallel to one
28、another.7.2 The surface roughness of exterior finishes shall notexceed 250 in. 6 m unless otherwise shown on the forgingdrawing or stated in the order or the contract.7.3 The surfaces of the forging to be examined shall be freeof extraneous material such as loose scale, paint, dirt, and soforth.8. P
29、rocedure8.1 General:8.1.1 As far as practicable, subject the entire volume of theforging to ultrasonic examination. Because of radii at changeof sections and other local configurations, it may be impossibleto examine some sections of a forging.8.1.2 Perform the ultrasonic examination after heat trea
30、t-ment for mechanical properties (exclusive of stress-relieftreatments) but prior to drilling holes, cutting keyways, tapers,grooves, or machining sections to contour. If the configurationof the forging required for the treatment for mechanicalproperties prohibits a subsequent complete examination o
31、f theforging, it shall be permissible to examine prior to treatment formechanical properties. In such cases, reexamine the forgingultrasonically as completely as possible after heat treatment.8.1.3 To ensure complete coverage of the forging volume,index the search unit with at least 15 % overlap wit
32、h each pass.8.1.4 For manual scanning, do not exceed a scanning rate of6 in./s 150 mm/s.8.1.5 For automated 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
33、 device to function. At no timeshall the scanning speed exceed the speed at which anacceptable calibration was made.8.1.6 If possible, scan all sections of forgings in twoperpendicular directions.8.1.7 Scan disk forgings using a straight beam techniquefrom at least one flat face and radially from th
34、e circumference,whenever practicable.8.1.8 Scan cylindrical sections and hollow forgings radiallyusing a straight-beam technique. When practicable, also exam-ine the forging in the axial direction.8.1.9 In addition, examine hollow forgings by angle-beamtechnique from the outside diameter surface as
35、required in8.3.1.8.1.10 In rechecking or reevaluation by manufacturer orpurchaser, use comparable equipment, search units, frequency,and couplant.8.1.11 Forgings may be examined either stationary or whilerotating in a lathe or on rollers. If not specified by thepurchaser, either method may be used a
36、t the manufacturersoption.8.2 Straight-Beam Examination:A 388/A 388M 0728.2.1 For straight-beam examination 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 examini
37、ng 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 detectability offlaws.8.2.2 Establish the instrument sensitivity by either thereflection, reference-block technique, or DGS metho
38、d (seeAppendix X3 for an explanation of the DGS method).8.2.2.1 Back-Reflection Technique (Back-Reflection 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 b
39、ack reflection approximately 75 % of the full-screenheight from the opposite side of the forging. Scan the 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. Recalibra
40、tion isrequired for significant changes in section thickness or diam-eter.NOTE 1High sensitivity levels are not usually employed when in-specting austenitic steel forgings due to attendant high level of “noise” or“hash” caused by coarse grain structure.8.2.2.2 Reference-Block CalibrationThe test sur
41、faceroughness 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 block.Utilize the attenuator in order to set up on amplitudes larger
42、than 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 block or blocks tocompensate for examination surface curvature (a
43、n example is given inAppendix X1).8.2.2.3 DGS CalibrationPrior to use, verify that the DGSoverlay matches the transducer size and frequency. Accuracyof the overlay can be verified by reference blocks andprocedures outlined in Practice E 317. Overlays are to beserialized to match the ultrasonic trans
44、ducer and pulse echotesting system that they are to be utilized with.8.2.2.4 Choose the appropriate DGS scale 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
45、 theprobe on the forging, adjust the gain to make the first back-wallecho appear clearly on CRT screen. Using 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
46、 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 can
47、be directly read from the CRT screen. These flaw sizes are theequivalent flat bottom reflector that can be used as a referencepoint.NOTE 3The above can be utilized on all solid forgings. Cylindricalhollow forgings, and drilled or bored forgings must be corrected tocompensate for attenuation due to t
48、he central hole (see Appendix X4).8.2.3 RecalibrationAny change in the search unit, cou-plant, instrument setting, or scanning speed from that used forcalibration shall require recalibration. Perform a calibrationcheck at least once every 8 h shift. When a loss of 15 % orgreater in the gain level is
49、 indicated, reestablish the requiredcalibration and reexamine all of the material examined in thepreceding calibration period. When an increase of 15 % orgreater in the gain level is indicated, reevaluate all recordedindications.8.2.4 During the examination of the forging, monitor theback reflection for any significant reduction in amplitude.Reduction in back-reflection amplitude may indicate not onlythe presence of a discontinuity but also poor coupling of thesearch unit with the surface of the forging, nonparallel back-reflection surface, or
