1、Designation: E 242 01 (Reapproved 2005)e1Standard Reference Radiographs forAppearances of Radiographic Images as Certain ParametersAre Changed1This standard is issued under the fixed designation E 242; the number immediately following the designation indicates the year oforiginal adoption or, in the
2、 case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.e1NOTEA sentence about reference radiograph films was editorially added to 1.2 in December 2005.1.
3、 Scope1.1 This document describes the appearance of a radio-graphic image where fundamental components 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 geometricalco
4、nfiguration of the object under investigation as well as itsassociated radiographic set-up.1.2 These reference radiographs2consist of four compositeillustrations3and show how such factors as radiation energy,specimen thickness, and film properties affect the radiographicimage. The reference radiogra
5、ph films are an adjunct to thisdocument and must be purchased separately from ASTM ifneeded.1.3 The values 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
6、 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:4E94 Guide for Radiographic ExaminationE 746 Test Method for Determining Relative Image QualityResponse o
7、f Industrial Radiographic Film SystemsE 1316 Terminology for Nondestructive TestingE 1815 Test Method for Classification of Film Systems forIndustrial Radiography2.2 ASTM Adjuncts:Reference Radiographs for Appearances of RadiographicImages as Certain Parameters Are Changed33. Terminology3.1 Definiti
8、ons: For definitions of terms used in this docu-ment, see Terminology E 1316, Section D.4. Significance 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 uponseve
9、ral radiographic parameters such as source energy level,film system, type and thickness of intensifying 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 aspec
10、ific technique. This standard may also be used in conjunc-tion with Test Method E 1815 or with Test Method E 746 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-gra
11、phic system sensitivity.5. Factors Affecting Radiographic Appearance5.1 The final interpretation of the 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 th
12、isappearance. The appearance of a radiographic image is affectedmainly by:5.1.1 X-ray or gamma ray energy.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 d
13、iscontinuity,1These reference radiographs are under the jurisdiction of ASTM CommitteeE07 on Nondestructive Testing and is the direct responsibility of SubcommitteeE07.02 on Reference Radiographs.Current edition approved Dec. 1, 2005. Published February 2006. Originallyapproved in 1964. Last previou
14、s edition approved in 2001 as E 242 - 01.2For 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 Service at servi
15、ceastm.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.c = constant,d1d2= minimum density change perceptible by
16、 eye,G = film gradient, = linear absorption coefficient (effective),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 f
17、unction of film gradient.5.3 Although not clearly indicated by 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.
18、by 12-in.welded steel plate which contained discontinuities in 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 include
19、s the identicalimage of the discontinuities in the weld, was selected 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 se
20、rve as the reference radio-graphs for this document. Following 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 th
21、e 10 radiographs taken of the welded steel plate,built up to 2 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 radi
22、ographs taken of the welded steel plate,built up to 6 in. 152 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 radiog
23、raphs.)All compositesets of radiographs show the change in radiographic 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.
24、The extent to which theimage deteriorates over time is a function 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 an
25、d tear, includingscratches, abrasions, stains, and so forth. Any 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 radiograp
26、hic appear-ance of a given discontinuity becomes less distinct 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
27、gamma rayenergies.7.2 Another condition that affects radiographic 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.
28、2.1 The X-ray or gamma ray beam divergence whichproduces unsharpness 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
29、effect is illustratedin this document by the composite set of 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 E 1815) and Fine Gra
30、in (comparable to class II ofTest Method E 1815). Comparisons of 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.
31、 Conclusions and Summary9.1 For a constant specimen thickness, the 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
32、 energy remaining constant.9.3 All other factors remaining constant, as the film ischanged from very fine grain (class I of Test Method E 1815)to fine grain (class II of Test Method E 1815), the radiographicappearance of the discontinuities becomes less distinct.9.4 For specimens of uniform thicknes
33、s, these data revealthat the most distinct radiographic appearance 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 ra
34、ys; referenceradiographs; steel; unsharpness; welds; x-rayE 242 01 (2005)e12EXPLANATORY 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
35、to limit the usefulness ofany source of radiation. The radiographs included 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 sp
36、ecimen (as seen in the 10 in. by 12 in. 254 mm by305 mm full-size reproduction). 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 l
37、ine connecting the imageof the two drilled holes in the plate was between 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.ASTM International takes no position respecting the validity of any patent rights
38、asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any tim
39、e by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will r
40、eceive 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 on Standards, at the address shown below.This standard is copyrighted by ASTM I
41、nternational, 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 th
42、rough the ASTM website(www.astm.org).TABLE 1 Technique DataNOTE 11 in. = 25.4 mmSourceLead ScreensComposite IllustrationFilm NotesABC DSteel ThicknessFront, in. Back, in. 1 in. 2 in. 4 in. 6 in.150 kVp 0.005 0.005 x . . . Fine grain14 in. lead mask250 kVP 0.005 0.005 . x . . Fine grain14 in. lead ma
43、sk1MVH0.0300.0300.0050.0100.0100.005x.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 0.030 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 .E 242 01 (2005)e13
