1、Designation: A 745/A 745M 94 (Reapproved 2009)Standard Practice forUltrasonic Examination of Austenitic Steel Forgings1This standard is issued under the fixed designationA 745/A 745M; the number immediately following the designation indicates the yearof original adoption or, in the case of revision,
2、 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. Scope1.1 This practice2covers the standards and procedures forthe contact, pulse-echo ultrasonic examination of au
3、steniticsteel forgings by the straight or angle beam techniques, or both.1.2 This practice shall be used whenever the inquiry, pro-posal, contract, order, or specification states that austenitic steelforgings are to be subject to ultrasonic examination in accor-dance with Practice A 745/A 745M. Ultr
4、asonic examination ofnonmagnetic retaining ring forgings should be made to PracticeA 531/A 531M, not to this practice.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, eachsy
5、stem shall be used independently of the other. Combiningvalues from the two systems may result in non-conformancewith the standard.1.4 This practice and the applicable material specificationsare expressed in both inch-pound units and SI units. However,unless the order specifies the applicable “M” sp
6、ecificationdesignation SI units, the material shall be furnished toinch-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
7、 determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:3A 531/A 531M Practice for Ultrasonic Examination ofTurbine-Generator Steel Retaining RingsE 317 Practice for Evaluating Performance Characteristicsof Ultrasonic Pulse-Echo Testing Instrume
8、nts and Systemswithout the Use of Electronic Measurement InstrumentsE 428 Practice for Fabrication and Control of Metal, Otherthan Aluminum, Reference Blocks Used in UltrasonicTesting2.2 American Society for Nondestructive Testing Docu-ment:SNT-TC-1A Recommended Practice for NondestructivePersonnel
9、Qualification and Certification43. Ordering Information3.1 When this practice is to be applied to an inquiry orpurchase order, the purchaser shall furnish the followinginformation:3.1.1 Quality level of examination (see Section 12).3.1.2 Additional requirements to this practice.3.1.3 Applicability o
10、f supplementary requirements (seeSupplementary Requirements section).3.2 When specified, the manufacturer shall submit an ex-amination procedure for purchaser approval that shall include,but not be limited to, a sketch of the configuration as presentedfor ultrasonic examination showing the surfaces
11、to be scanned,scanning directions, notch locations and sizes (if applicable),extent of coverage (if applicable), and an instruction listingcalibration and inspection details and stage of manufacture.4. Apparatus4.1 An electronic, pulsed, reflection type of instrument shallbe used for this examinatio
12、n. The system shall have a mini-mum capability for operating at frequencies from 0.5 to 5.0MHz. Either video or r-f presentation is acceptable.4.2 The ultrasonic instrument shall provide linear presenta-tion (within 6 5 % of the signal height) for at least 75 % of thescreen height (sweep line to top
13、 of screen). This 5 % linearityis descriptive of the screen presentation of amplitude. Instru-ment linearity shall be verified in accordance with the intent ofPractice E 317.4.3 Instruments with incremental gain control (accurateover its useful range to 6 10 % of the nominal attenuationratio) shall
14、be used when possible to allow measurement ofsignals beyond the linear display range of the instrument.4.4 Search Units: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
15、and Billets.Current edition approved April 1, 2009. Published April 2009. Originallyapproved in 1977. Last previous edition approved in 2003 as A 745/A 745M 94(2003).2For ASME Boiler and Pressure Vessel Code applications see related Specifi-cation SA-745/SA-745M in Section II of that Code.3For refer
16、enced 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 from the American Society for Nondestructive Testing, 1711 A
17、rlin-gate Lane, P.O. Box 28518, Columbus, OH 432280518.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4.4.1 Search units having transducers of either quartz orother piezoelectric materials may be employed.4.4.2 The maximum nominal a
18、ctive area of 112 in.2970mm2 with12-in. 13 mm minimum to 118-in. 30 mmmaximum dimensions or34-in. 20 mm diameter minimumdimension shall be used for straight-beam scanning.4.4.3 Angle-beam scanning transducers shall have a nomi-nal active area of12 to 1 in.2325 to 650 mm2. The search unitused for ang
19、le-beam examination shall produce a beam angleof 30 to 70 in the material.4.4.4 Other search units, including frequencies other thanthose listed in Section 8 , may be used for evaluating andpinpointing indications of discontinuities.4.5 CouplantA suitable couplant having good wettingcharacteristics
20、shall be used between the transducer and theexamination surface. The same couplant shall be used forcalibration and examination.4.6 Reference Blocks:4.6.1 All ultrasonic standard reference blocks shall be inaccordance with the general guidelines of Practice E 428.However, absolute conformance to Pra
21、ctice E 428 is notmandatory due to the nature of the material covered by thispractice.4.6.2 The reference block grain size, as measured by therelative acoustic penetrability of the reference blocks, shouldbe reasonably similar to the forging under examination. How-ever, it must be recognized that la
22、rge austenitic forgings varyconsiderably in acoustic penetrability throughout their volumedue to variations in grain size and structure. Reference blocksshould be chosen that reasonably approximate the averagepenetrability of the forging under examination. Supplementaryblocks of coarser or finer gra
23、in may be used for evaluation ofindications as covered in Section 11.4.6.3 As an alternative method, where practicable, theappropriate size of reference hole (or holes) or notches may beplaced in representative areas of the forging for calibration andexamination purposes when removed by subsequent m
24、achin-ing. When holes or notches are not removed by subsequentmachining, the purchaser must approve the location of holes ornotches.5. Personnel Requirements5.1 Personnel performing the ultrasonic examinations to thispractice shall be qualified and certified in accordance with awritten procedure con
25、forming to Recommended Practice No.SNT-TC-1A or another national standard that is acceptable toboth the purchaser and the supplier.6. Forging Conditions6.1 Forgings shall be ultrasonically examined after heattreating.6.2 The surfaces of the forging to be examined shall be freeof extraneous material
26、such as loose scale, paint, dirt, etc.6.3 The surface roughness of scanning surfaces shall notexceed 250 in. 6 m unless otherwise stated in the order orcontract.6.4 The forgings shall be machined to a simple configura-tion, that is, rectangular or parallel or concentric surfaceswhere complete volume
27、tric coverage can be obtained.6.5 In certain cases, such as with contour forged parts, itmay be impractical to assure 100 % volumetric coverage. Suchforgings shall be examined to the maximum extent possible. Aprocedure indicating the extent of examination coverage shallbe submitted for the purchaser
28、s approval (see 3.2).7. Procedure7.1 Perform the ultrasonic examination after heat treatmentwhen the forging is machined to the ultrasonic configurationbut prior to drilling holes, cutting keyways, tapers, grooves, ormachining sections to final contour.7.2 To ensure complete coverage of the forging
29、volumewhen scanning, index the search unit with at least 15 % overlapwith each pass.7.3 The scanning rate shall not exceed 6 in. 150 mm/s.7.4 Scan all regions of the forging in at least two perpen-dicular directions to the maximum extent possible.7.5 Scan disk and disk-type forgings using a straight
30、 beamfrom at least one flat face and radially from the circumferencewhen practicable. For the purposes of this practice, a disk is acylindrical shape where the diameter dimension exceeds theheight dimension. Disk-type forgings made as upset-forged“pancakes” shall be classified as disks for inspectio
31、n purposesalthough at the time of inspection, the part may have a centerhole, counterturned steps, or other detail configuration.7.6 Scan cylindrical sections, ring and hollow forgings fromthe entire external surface (sides or circumference), using thestraight-beam technique, and scan the forging in
32、 the axialdirection to the extent possible. When the length divided by thediameter ratio (slenderness ratio) exceeds 6 to 1 (or axial lengthexceeds 24 in. 600 mm), scan axially from both end surfacesto the extent possible. If axial penetration is not possible due toattenuation, angle-beam examinatio
33、n directed axially may besubstituted in place of axial straight beam. Examine ring andhollow forgings having an outside-diameter to inside-diameterratio of less than 2 to 1 and a wall thickness less than 8 in. 200mm by angle-beam techniques from the outside diameter orinside diameter, or both, using
34、 full node or half-node technique(see 10.1.2 and 10.1.3) as necessary to achieve either 100 %volumetric coverage or the extent of coverage defined by anapproved procedure (see 3.2).8. Examination Frequency8.1 Perform all ultrasonic examination at the highest fre-quency practicable (as specified in 8
35、.1.1, 8.1.2,or8.1.3) thatwill adequately penetrate the forging thickness and resolve theapplicable reference standard. Include in the ultrasonic exami-nation report the examination frequency used. Determine thetest frequency at the time of actual examination by thefollowing guidelines:8.1.1 The nomi
36、nal test frequency shall be 2.25 MHz. Use ofthis frequency will generally be restricted due to attenuation.8.1.2 One megahertz is acceptable and will be the frequencygenerally applicable.8.1.3 When necessary, due to attenuation, 0.5-MHz exami-nation frequency may be used. The purchaser may requestno
37、tification before this lower frequency is employed.A 745/A 745M 94 (2009)28.1.4 In the event that adequate penetration of certainregions is not possible even at 0.5 MHz, alternative nonde-structive examination methods (such as radiography) may beemployed to ensure the soundness of the forging by agr
38、eementbetween the purchaser and the manufacturer.9. Straight-Beam Examination9.1 Method of Calibration:9.1.1 Perform calibration for straight-beam examination onthe flat-bottom hole size determined by the applicable qualitylevel (see Section 12).9.1.2 Determine the calibration method by the test met
39、aldistance involved.9.1.2.1 Thicknesses up to 6 in. 150 mm may be examinedusing either the single-block or the distance-amplitude curvecalibration method.(a) (a) Single-Block MethodEstablish the test sensitiv-ity on the reference standard representing the forging thick-ness. Drill flat-bottom holes
40、normal to the examining surface,to midsection in material up to 1.5 in. 40 mm in thickness andat least 0.75 in. 20 mm in depth but no deeper thanmidsection in thicknesses from 1.5 to 6 in. 40 to 150 mm.Make evaluations of indications at the estimated discontinuitydepth at which they are observed usi
41、ng supplementary refer-ence standards, if necessary.(b) (b) Distance-Amplitude-Curve Correction MethodEstablish the test sensitivity on the reference standard whosemetal travel distance represents the greater metal travel dis-tance of the part under examination, within 61 in. 25 mm.9.1.2.2 Examine t
42、hicknesses from 6 to 24 in. 150 to 600mm using the distance-amplitude calibration method. Calibra-tion to12 thickness test metal distance may be used providedexaminations from two opposing surfaces are made.9.1.2.3 For metal travel distances over 24 in. 600 mm,perform one of the following examinatio
43、ns:(a) (a) Perform a back-reflection examination from atleast one surface to QL-5 (see 12.1.1) or to a purchaser-approved procedure (see 3.2).(b) (b) On hollow-round forgings with wall thicknessesless than 8 in. 200 mm, perform an axial angle-beam scan inplace of the straight-beam scan from the end
44、surfaces. Cali-bration for this scan may be established on the existing axialnotches required for the circumferential scan or on transverseoriented notches installed specifically for axial angle beam.9.2 Calibration ProcedureOver an indication-free area ofthe forging and with the proper test frequen
45、cy, adjust theamplitude of the back reflection to the maximum limit ofvertical linearity of the instrument. The adjusted instrumentsensitivity display shall be the primary calibration reference forboth the single-block and multiple-block calibration methods.If, at this gain setting, the amplitude re
46、sponse from theflat-bottom hole in the longest calibration block is not equal toor greater than 0.5 in. 13 mm sweep-to-peak, adjust theinstrument gain further to obtain a 0.5-in. 13 mm sweep-to-peak minimum response. To complete the distance-amplitudecorrection curve, determine the remaining points
47、defining theshape of the curve at this adjusted gain setting and mark thecurve on the shield of the cathode ray tube or plot on a graph.At least three blocks shall be used with test metal distances of3 in. 75 mm12 T, and T. However, the distance between anyof the test blocks shall be 112 in. 40 mm m
48、inimum. Ifindications closer than 3 in. 75 mm from the initial pulsemust be evaluated, an additional block with 112 in. 40 mmtest metal distance shall be used. This is the fixed referenceagainst which all indications shall be evaluated at the maxi-mum obtainable response at whatever depth the indica
49、tions areobserved. This will constitute an acceptable examination ifthere are no indications exceeding the acceptance limits. Inlarge forgings, it is expected that a portion of the distance-amplitude curve will be above the vertical linearity limits of theinstrument. If an indication appears in this area, readjust theinstrument through the use of a calibrated gain control orthrough recalibration to the initial calibration level to bring theappropriate portion of the presentation on screen for evaluationof that specifi
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