1、Designation: A388/A388M 15A388/A388M 16 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
2、revision, the 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 practice2 covers the examination procedures for the contact, pulse-echo ultrasonic examina
3、tion of steel forgings by thestraight and angle-beam techniques. The straight beam techniques include utilization of the DGS (Distance Gain-Size) method. SeeAppendix X3.1.2 This practice is to be used whenever the inquiry, contract, order, or specification states that forgings are to be subject toul
4、trasonic examination in accordance with Practice A388/A388M.1.3 Supplementary requirements of an optional nature are provided for use at the option of the purchaser. The supplementaryrequirements shall apply only when specified individually by the purchaser in the purchase order or contract.1.4 The
5、values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in eachsystem may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from thetwo systems may result in non-conformance with the s
6、tandard.1.5 This specification and the applicable material specifications are expressed in both inch-pound units and SI units. However,unless the order specifies the applicable “M” specification designation SI units, the material shall be furnished to inch-poundunits.1.6 This standard does not purpo
7、rt to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:3A469/A
8、469M Specification for Vacuum-Treated Steel Forgings for Generator RotorsA745/A745M Practice for Ultrasonic Examination of Austenitic Steel ForgingsA788/A788M Specification for Steel Forgings, General RequirementsE317 Practice for Evaluating Performance Characteristics of Ultrasonic Pulse-EchoTestin
9、g Instruments and Systems without theUse of Electronic Measurement InstrumentsE428 Practice for Fabrication and Control of Metal, Other than Aluminum, Reference Blocks Used in Ultrasonic TestingE1065/E1065M Practice for Evaluating Characteristics of Ultrasonic Search Units2.2 Other Document: 4Recomm
10、ended Practice for Nondestructive Personnel Qualification and Certification SNT-TC-1A, (1988 or later)3. Terminology3.1 Definitions:3.1.1 indication levels (clusters), nfive or more indications in a volume representing a 2-in. 50-mm or smaller cube in theforging.1 This practice is under the jurisdic
11、tion of ASTM Committee A01 on Steel, Stainless Steel and Related Alloys and is the direct responsibility of Subcommittee A01.06on Steel Forgings and Billets.Current edition approved July 15, 2015May 1, 2016. Published July 2015May 2016. Originally approved in 1955. Last previous edition approved in
12、20112015 asA388/A388M 11.A388/A388M 15. DOI: 10.1520/A0388_A0388M-15.10.1520/A0388_A0388M-16.2 For ASME Boiler and Pressure Vessel Code applications see related Specification SA-388/SA-388M in Section II of that Code.3 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM
13、 Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.4 Available from American Society for Nondestructive Testing (ASNT), P.O. Box 28518, 1711 Arlingate Ln., Columbus, OH 43228-0518, http:/www.asnt
14、.org.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prio
15、r editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 1942
16、8-2959. United States13.1.2 individual indications, nsingle indications showing a decrease in amplitude as the search unit is moved in any directionfrom the position of maximum amplitude and which are too small to be considered traveling or planar.3.1.3 planar indications, nindications shall be cons
17、idered continuous over a plane if they have a major axis greater than 1 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 leading edge moves a distance equivalent to 1 in. 25 mm or more of metaldepth with m
18、ovement of the transducer over the surface of the forging.4. Significance and Use4.1 This practice shall be used when ultrasonic inspection is required by the order or specification for inspection purposes wherethe acceptance of the forging is based on limitations of the number, amplitude, or locati
19、on of discontinuities, or a combinationthereof, which give rise to ultrasonic indications.4.2 The ultrasonic quality level shall be clearly stated as order requirements.5. Ordering Information5.1 When this practice is to be applied to an inquiry, contract, or order, the purchaser shall so state and
20、shall also furnish thefollowing information:5.1.1 Designation number (including year date),5.1.2 Method of establishing the sensitivity in accordance with 9.2.2 and 9.3.3 (Vee- (DGS (Distance Gain Size), Vee- orrectangular-notch),5.1.2.1 The diameter and test metal distance of the flat-bottom hole a
21、nd the material of the reference block in accordance with9.2.2.2,5.1.3 Quality level for the entire forging or portions thereof in 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 ultrasoni
22、c, pulsed, reflection type of instrument shall be used for this examination. The systemshall have a minimum capability for examining at frequencies from 1 to 5 MHz. On examining austenitic stainless forgings thesystem shall have the capabilities for examining at frequencies down to 0.4 MHz.6.1.1 App
23、aratus Qualification and CalibrationBasic qualification of the ultrasonic test instrument shall be performed atintervals not to exceed 12 months or whenever maintenance is performed that affects the equipment function. The date of the lastcalibration and the date of the next required calibration sha
24、ll be displayed on the test equipment.6.1.2 The ultrasonic instrument shall provide linear presentation (within 5 %) for at least 75 % of the screen height (sweep lineto top of screen). The 5 % linearity referred to is descriptive of the screen presentation of amplitude. Instrument linearity shall b
25、everified in accordance with the intent of Practice E317.Any set of blocks processed in accordance with Practice E317 or E428 maybe used to establish the specified 65 % instrument linearity.6.1.3 The electronic apparatus shall contain an attenuator (accurate over its useful range to 610 % (+1 dB) of
26、 the amplituderatio) which will allow measurement of indications beyond the linear range of the instrument.6.2 Search Units, having a transducer with a maximum active area of 1 in.2 650 650 mm2 with 34 in. 20 mm minimumto 118 in. 30 mm maximum dimensions shall be used for straight-beam scanning (see
27、 9.2); and search units with 12 in. 13 mmminimum to 1 in. 25 mm maximum dimensions shall 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 and pinpointing indications.6.3 Couplants, having good
28、 wetting characteristics such as SAE No. 20 or No. 30 motor oil, glycerin, pine oil, or water shallbe used. Couplants may not be comparable to one another and the same couplant shall be used for calibration and examination.6.4 Reference Blocks, containing flat-bottom holes may be used for calibratio
29、n of equipment in accordance with 6.1.2 and maybe used to establish recording levels for straight-beam examination when so specified by the order or contract.6.5 DGS Scales, matched to the ultrasonic test unit and transducer to be utilized, may be used to establish recording levels forstraight or an
30、gle beam examination, when so specified by the order or contract. The DGS scale range must be selected to includethe full thickness cross-section of the forging to be examined. An example of a DGS overlay is found in Appendix X3.6.5.1 As an alternative to using DGS overlays, an ultrasonic instrument
31、 having DGS software, integral decibel gain or attenuatorcontrols in combination with a specifically paired transducer and DGS diagram may be used to evaluate ultrasonic indications.7. Personnel Requirements7.1 Personnel performing the ultrasonic examinations to this practice shall be qualified and
32、certified in accordance with a writtenprocedure conforming to Recommended Practice No. SNT-TC-1A (1988 or later) or another national standard that is acceptableto both the purchaser and the supplier.A388/A388M 1628. Preparation of Forging for Ultrasonic Examination8.1 Unless otherwise specified in t
33、he order or contract, the forging shall be machined to provide cylindrical surfaces for radialexamination in the case of round forgings; the ends of the forgings shall be machined perpendicular to the axis of the forging forthe axial examination. Faces of disk and rectangular forgings shall be machi
34、ned flat and parallel to one another.8.2 The surface roughness of exterior finishes shall not exceed 250 in. 6 m where the definition for surface finish is as perSpecification A788/A788M unless otherwise shown on the forging drawing or stated in the order or the contract.8.3 The surfaces of the forg
35、ing to be examined shall be free of extraneous material such as loose scale, paint, dirt, and so forth.9. Procedure9.1 General:9.1.1 As far as practicable, subject the entire volume of the forging to ultrasonic examination. Because of radii at change ofsections and other local configurations, it may
36、 be impossible to examine some sections of a forging.9.1.2 Perform the ultrasonic examination after heat treatment for mechanical properties (exclusive of stress-relief treatments)but prior to drilling holes, cutting keyways, tapers, grooves, or machining sections to contour. If the configuration of
37、 the forgingrequired for the treatment for mechanical properties prohibits a subsequent complete examination of the forging, it shall bepermissible to examine prior to treatment for mechanical properties. In such cases, reexamine the forging ultrasonically ascompletely as possible after heat treatme
38、nt.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 of 6 in./s 150 mm/s.9.1.5 For automated scanning, adjust scanning speed or instrument repetition rate, or both, to perm
39、it detection of the smallestdiscontinuities referenced in the specification and to allow the recording or signaling device to function. At no time shall thescanning speed exceed the speed at which an acceptable calibration was made.9.1.6 If possible, scan all sections of forgings in two perpendicula
40、r directions.9.1.7 Scan disk forgings using a straight beam technique from at least one flat face and radially from the circumference,whenever practicable.9.1.8 Scan cylindrical sections and hollow forgings radially using a straight-beam technique. When practicable, also examinethe forging in the ax
41、ial direction.9.1.9 In addition, examine hollow forgings by angle-beam technique from the outside diameter surface as required in 9.3.1.9.1.10 In rechecking or reevaluation by manufacturer or purchaser, use comparable equipment, search units, frequency, andcouplant.9.1.11 Forgings may be examined ei
42、ther stationary or while rotating in a lathe or on rollers. If not specified by the purchaser,either method may be used at the manufacturers option.9.2 Straight-Beam Examination:9.2.1 For straight-beam examination use a nominal 214-MHz search unit whenever practicable; however, 1 MHz is the preferre
43、dfrequency for coarse grained austenitic materials and long testing distances. In many instances on examining coarse grainedaustenitic materials it may be necessary to use a frequency of 0.4 MHz. Other frequencies may be used if desirable for betterresolution, penetrability, or detectability of flaw
44、s.9.2.2 Establish the instrument sensitivity by either the reflection, reference-block technique, or DGS method (see Appendix X3for an explanation of the DGS method).9.2.2.1 Back-Reflection Technique (Back-Reflection Calibration Applicable to Forgings with Parallel Entry and BackSurfaces)With the at
45、tenuator set at an appropriate level, for example 5 to 1 or 14 dB, adjust the instrument controls to obtaina back reflection approximately 75 % of the full-screen height from the opposite side of the forging. Scan the forging at themaximum amplification setting of the attenuator (attenuator set at 1
46、 to 1). Carry out the evaluation of discontinuities with the gaincontrol set at the reference level. Recalibration is required for significant changes in section thickness or diameter.NOTE 1High sensitivity levels are not usually employed when inspecting austenitic steel forgings due to attendant hi
47、gh level of “noise” or “hash”caused by coarse grain structure.9.2.2.2 Reference-Block CalibrationThe test surface roughness on the calibration standard shall be comparable to, but nobetter than, the item to be examined. Adjust the instrument controls to obtain the required signal amplitude from the
48、flat-bottomhole in the specified reference block. Utilize the attenuator in order to set up on amplitudes larger than the vertical linearity of theinstrument. In those cases, remove the attenuation prior to scanning the forging.NOTE 2When flat-surfaced reference block calibration is specified, adjus
49、t the amplitude of indication from the reference block or blocks tocompensate for examination surface curvature (an example is given in Appendix X1).9.2.2.3 DGS CalibrationPrior to use, verify that the DGS overlay or electronic DGS curve matches the transducer size andfrequency. Accuracy of the overlay can be verified by reference blocks and procedures outlined in Practice E317. Overlays are tobe serialized to match the ultrasonic transducer and pulse echo testing system that they are to be utilized with. Instruments withelectronic DGS m
