1、Designation: E242 01 (Reapproved 2010)Standard Reference Radiographs forAppearances of Radiographic Images as Certain Parametersare Changed1This standard is issued under the fixed designation E242; the number immediately following the designation indicates the year oforiginal adoption or, in the cas
2、e of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This document describes the appearance of a radio-graphic image where fundamental component
3、s of image qual-ity are changed, that is, variables such as whether an X-ray orgamma ray source was used, the characteristics of the radio-graphic film and intensifying screens, and the geometricalconfiguration of the object under investigation as well as itsassociated radiographic set-up.1.2 These
4、reference radiographs2consist of four compositeillustrations3and show how such factors as radiation energy,specimen thickness, and film properties affect the radiographicimage. The reference radiograph films are an adjunct to thisdocument and must be purchased separately from ASTM ifneeded.1.3 The v
5、alues stated in inch-pound units are to be regardedas the standard.1.4 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 ap
6、plica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:4E94 Guide for Radiographic ExaminationE746 Practice for Determining Relative Image QualityResponse of Industrial Radiographic Imaging SystemsE1316 Terminology for Nondestructive ExaminationsE1815 Test Meth
7、od for Classification of Film Systems forIndustrial Radiography2.2 ASTM Adjuncts:Reference Radiographs for Appearances of RadiographicImages as Certain Parameters Are Changed33. Terminology3.1 Definitions: For definitions of terms used in this docu-ment, see Terminology E1316, Section D.4. Significa
8、nce and Use4.1 A key consideration with any radiographic system is itscapability to resolve detail (that is, sensitivity). The degree ofobtainable sensitivity with a given system is dependent uponseveral radiographic parameters such as source energy level,film system, type and thickness of intensify
9、ing screens, andmaterial thickness radiographed. These reference radiographspermit the user to estimate the degree of sensitivity change thatmay be obtained when these parameters are varied from aspecific technique. This standard may also be used in conjunc-tion with Test Method E1815 or with Test M
10、ethod E746 toprovide a basis for developing data for evaluation of a usersspecific system. This data may assist a user in determiningappropriate parameters for obtaining desired degrees of radio-graphic system sensitivity.5. Factors Affecting Radiographic Appearance5.1 The final interpretation of th
11、e radiograph is greatlyaffected by the appearance of a discontinuity. A poor techniquecan minimize the radiographic appearance of a discontinuityand conversely the optimum technique can emphasize thisappearance. The appearance of a radiographic image is affectedmainly by:5.1.1 X-ray or gamma ray ene
12、rgy.5.1.2 Section thickness,5.1.3 Unsharpness, and5.1.4 Film and screen combinations.5.2 The equation that considers most of the above factors is:Dx 5 cd12 d2!/G#kx 1 1! (1)where:Dx = thickness of discontinuity,c = constant,d1d2= minimum density change perceptible by eye,G = film gradient,1These ref
13、erence radiographs are under the jurisdiction of ASTM CommitteeE07 on Nondestructive Testing and is the direct responsibility of SubcommitteeE07.02 on Reference Radiological Images.Current edition approved June 1, 2010. Published November 2010. Originallyapproved in 1964. Last previous edition appro
14、ved in 2005 as E242 - 01 (2005)1.DOI: 10.1520/E0242-01R10.2For ASME Boiler and Pressure Code applications see related ReferenceRadiographs SE-242 in the Code.3Available from ASTM Headquarters. Order RRE0242.4For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer
15、 Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States. = linear absorption coefficient (effec
16、tive),k = scattering coefficient, andx = section thickness.As the above equation shows, the minimum thickness ofdetectable discontinuity (Dx) is:5.2.1 A function of X-ray energy,5.2.2 A function of section thickness, and5.2.3 An inverse function of film gradient.5.3 Although not clearly indicated by
17、 the above relation, thesize of detectable discontinuity is also a function of unsharp-ness, see Guide E94.6. Radiographic Illustrations6.1 A series of 36 radiographs, each on 10-in. by 12-in.254-mm by 305-mm film, were taken of a 12-in. by 12-in.welded steel plate which contained discontinuities in
18、 the weld.These were taken to illustrate the differences in appearance ofthe radiographic image when techniques for taking radiographsare varied by changing the factors listed in Section 5.A2-in. by2-in. 51-mm by 51-mm area, which includes the identicalimage of the discontinuities in the weld, was s
19、elected and cutout from each 10-in. by 12-in. radiograph and arranged so as tomake four composite illustrations identified as Fig. 1 throughFig. 4. These composite illustrations are an abridged version ofthe original 36 radiographs and serve as the reference radio-graphs for this document. Following
20、 are brief descriptions ofthese figures.6.1.1 Figure 1Composite Illustration A consists of cutouts from the 10 radiographs taken of the 1-in. 25-mm thickwelded steel plate.6.1.2 Figure 2Composite Illustration B consists of cutouts from the 10 radiographs taken of the welded steel plate,built up to 2
21、 in. in thickness.6.1.3 Figure 3Composite Illustration C consists of cutouts from the 10 radiographs taken of the welded steel plate,built up to 4 in. in thickness.6.1.4 Figure 4Composite Illustration D consists of cutouts from the 6 radiographs taken of the welded steel plate,built up to 6 in. 152
22、mm in thickness.6.2 The radiographic appearance of discontinuities in 1, 2,4, and 6-in. thick steel is shown in the series of compositeradiographs. (These are full-scale reproductions of the sameselected area from all the reference radiographs.)All compositesets of radiographs show the change in rad
23、iographic appear-ance in the specified thickness of steel plate as the parametersof X-ray or gamma ray energy and film systems or both arechanged.6.3 Film DeteriorationRadiographic films are subject towear and tear from handling and use. The extent to which theimage deteriorates over time is a funct
24、ion of storage condi-tions, care in handling and amount of use. Reference radio-graph films are no exception and may exhibit a loss in imagequality over time. The radiographs should therefore be peri-odically examined for signs of wear and tear, includingscratches, abrasions, stains, and so forth. A
25、ny reference radio-graphs which show signs of excessive wear and tear whichcould influence the interpretation and use of the radiographsshould be replaced.7. Use of the Reference Radiographs7.1 As radiation energy increases, the radiographic appear-ance of a given discontinuity becomes less distinct
26、 because ofthe greater penetration of the radiation; that is, because ofdecreasing subject contrast. The reference radiographs permit acomparison of the radiographic appearance of the weld, atparticular thickness over a range of X-ray or gamma rayenergies.7.2 Another condition that affects radiograp
27、hic appearanceis the variation of thickness for a given X-ray or gamma rayenergy. As the thickness of examined material is increased, adiscontinuity becomes less distinct in the radiographic image.This is due to two predominant factors:7.2.1 The X-ray or gamma ray beam divergence whichproduces unsha
28、rpness on the film when traversing a largethickness.7.2.2 Scattered radiation within the material, which reducesthe radiographic contrast.7.2.3 The above processes are a function of material thick-ness and X-ray or gamma ray energy. This effect is illustratedin this document by the composite set of
29、radiographs or bydirect reference to the full-size radiographs.8. Film and Screens8.1 The X-ray film systems used in obtaining the illustrativedata were as follows: Very Fine Grain (comparable to class I ofTest Method E1815) and Fine Grain (comparable to class II ofTest Method E1815). Comparisons of
30、 these two film systemsare illustrated in the composite radiographs and within Table 1.8.2 Several different lead foil screen combinations wereused. The specific combination of lead foil screens for eachradiograph is noted in Table 1.9. Conclusions and Summary9.1 For a constant specimen thickness, t
31、he radiographicappearance of the discontinuities changes as the X-ray orgamma ray energy is varied.9.2 As the section thickness of specimen increases, theradiographic appearance of the discontinuities becomes lessdistinct, the radiation energy remaining constant.9.3 All other factors remaining const
32、ant, as the film ischanged from very fine grain (class I of Test Method E1815)tofine grain (class II of Test Method E1815), the radiographicappearance of the discontinuities becomes less distinct.9.4 For specimens of uniform thickness, these data revealthat the most distinct radiographic appearance
33、of the disconti-nuities occurs when the finest grain film and the lowest X-rayor gamma ray energy is used, consistent with a given specimenthickness and practical exposure time.10. Keywords10.1 film systems; discontinuities; gamma rays; referenceradiographs; steel; unsharpness; welds; x-rayE242 01 (
34、2010)2EXPLANATORY NOTESNOTE 1Total unsharpness factors such as source size, source-filmdistance, screens, film graininess, etc., must be considered in establishingtechniques (Guide E94).NOTE 2It is not the intent of this document to limit the usefulness ofany source of radiation. The radiographs inc
35、luded in this document areillustrative and not intended to be either inclusive or conclusive.APPENDIX(Nonmandatory Information)X1. ADDITIONAL TECHNICAL INFORMATIONX1.1 Radiation source was centered over drilled hole incenter of specimen (as seen in the 10 in. by 12 in. 254 mm by305 mm full-size repr
36、oduction). In 1 MV and 2 MV radiog-raphy, the radiation was projected towards the specimenthrough the target, using a transmitted beam.X1.2 Radiographic exposure was such that the film densityin the radiograph at the center of a line connecting the imageof the two drilled holes in the plate was betw
37、een 1.90 and 2.10.X1.3 All films were developed using procedures recom-mended in Guide E94.X1.4 Good contact between film and screens wasmaintained.TABLE 1 Technique DataNOTE 11 in. = 25.4 mmSourceLead ScreensComposite IllustrationFilm NotesABC DSteel ThicknessFront, in. Back, in. 1 in. 2 in. 4 in.
38、6 in.150 kVp 0.005 0.005 x . . . Fine grain14 in. lead mask250 kVP 0.005 0.005 . x . . Fine grain14 in. lead mask1MVH0.0300.0300.0050.0100.0100.005x.xx.xx.x.x.Very fine grainFine grainFine grain.2MVH0.0300.0050.0100.005xxxxxxxxVery fine grainFine grain.10 MV 0.040 0.010 x x x x Fine grain .15 MV 0.0
39、30 0.010 x x x x Very fine grain .Iridium 192H0.0050.0100.0100.010x.x.x.Fine grainFine grain.Cobalt-60 (212 C)H0.0050.0100.0100.010x.x.x.Fine grainFine grain.Cobalt-60 (1000 C) 0.010 0.010 . . x x Fine grain 0.080 in. lead filterRadium-226 (250 mg) 0.010 0.010 x x x . Fine grain .E242 01 (2010)3ASTM
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42、d should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee o
43、n Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).E242 01 (2010)4
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