1、Designation: E2869 17Standard Digital Reference Images forMagnesium Castings1This standard is issued under the fixed designation E2869; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parenthe
2、ses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 These digital reference images illustrate the types anddegrees of discontinuities that may be found in magnesium-alloy castings. The castings illustrate
3、d are in thicknesses of14in. (6 mm) and34 in. (19.1 mm).1.2 All areas of this standard may be open to agreementbetween the cognizant engineering organization and thesupplier, or specific direction from the cognizant engineeringorganization. These items should be addressed in the purchaseorder or the
4、 contract.1.3 The values stated in inch-pound units are to be regardedas standard. The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.1.4 These digital reference images are not intended toillustrate the types
5、and degrees of discontinuities found inmagnesium-alloy castings when performing film radiography.If performing film radiography of magnesium-alloy castings,refer to Reference Radiographs E155.1.5 Only licensed copies of the software and images shall beutilized for production examination. A copy of t
6、he ASTM/Userlicense agreement shall be kept on file for audit purposes.NOTE 1The set of digital reference images consists of 14 digital files,software to load the desired format and specific instructions on the loadingprocess. The 14 reference images illustrate eight grades of severity andcontain an
7、 image of a step wedge and two duplex wire gauges.1.6 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, health, and environmental practices and deter-mine the ap
8、plicability of regulatory limitations prior to use.1.7 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued b
9、y the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2E155 Reference Radiographs for Inspection of Aluminumand Magnesium CastingsE1316 Terminology for Nondestructive ExaminationsE2002 Practice for Determining Total Image Unsharpnessand B
10、asic Spatial Resolution in Radiography and Radios-copy2.2 SMPTE Practice3RP133 SMPTE Recommended Practice Specifications forMedical Diagnostic Imaging Test Pattern for TelevisionMonitors and Hard-Copy Recording Cameras2.3 ASTM Adjuncts4Digital Reference Images for Magnesium Castings3. Terminology3.1
11、 DefinitionsDefinitions of terms used in this standardmay be found in Terminology E1316.3.2 Definitions of Terms Specific to This Standard:3.2.1 The terms relating to discontinuities used in thesedigital reference images are described based upon radiologicalappearance. (See Note 2.)3.2.2 aliasingart
12、ifacts that appear in an image when thespatial frequency of the input is higher than the output iscapable of reproducing. This will often appear as jagged orstepped sections in a line or as moir patterns.3.2.3 contrast normalizationthe adjustment of contrastbetween the production image and the refer
13、ence image thatmakes the change in digital driving level versus change inthickness equal for both images.3.2.4 DDLdigital driving level also known as monitorpixel value.1This standard is under the jurisdiction of ASTM Committee E07 on Nonde-structive Testing and is the direct responsibility of Subco
14、mmittee E07.02 onReference Radiological Images.Current edition approved Nov. 1, 2017. Published November 2017. Originallyapproved in 2013. Last previous edition approved in 2013 as E286913. DOI:10.1520/E286917.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Custo
15、mer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from Society of Motion Picture and Television Engineers, 3 BarkerAvenue White Plains, NY 10601; or http:/www.smpte.org/smpte_store/4Availabl
16、e from ASTM International Headquarters. Order Adjunct No.RRE2869. Original adjunct produced in 2013.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international sta
17、ndard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.13.2.
18、5 foreign materialsappear as isolated, irregular, orelongated variations in brightness, not corresponding to varia-tions in thickness of material, nor to cavities. They may be dueto the presence of sand, slag, oxide or dross, or metal ofdifferent density.3.2.6 gas holesappear as round or elongated,
19、smooth-edged dark spots in a negative image, occurring individually, inclusters, or distributed throughout the casting.3.2.7 gas porosityrepresented by round or elongated darkspots in a negative image corresponding to minute voidsusually distributed through the entire casting.3.2.8 measured resoluti
20、onthe characteristic resolution of adigital radiographic system as measured in accordance with8.5.3.2.9 micro shrinkage (feathery type)micro shrinkagehaving an elongated appearance resembling feather-likestreaks.3.2.10 micro shrinkage (sponge type)micro shrinkagehaving a sponge-like appearance, and
21、more massive andequiaxed than the feathery type.3.2.11 reacted sand inclusionsappear as “spottysegregation,” which is, sharply defined round light areas (in anegative image) about 1 mm in diameter, and often with therim lighter than the center. They are entrapped sand particlesthat underwent reactio
22、n with molten magnesium alloys con-taining zirconium (see Note 3).3.2.12 segregationsappear as variations in imagedarkness, which can be explained by segregation of elementsof atomic numbers different from that of the matrix.3.2.12.1 gravity segregationappears lighter in a negativeimage and may rang
23、e from a mottling-type effect throughwhite-diffused spots blending with the matrix, to a cloud-likeappearance in more severe cases. They are agglomerations ofparticles precipitated at temperatures above liquidus (see Note3).3.2.12.2 eutectic segregationtype of segregation is gener-ally represented w
24、hen a defect or discontinuity develops duringsolidification and is fed with a near eutectic residual liquid richwith alloying elements that have a high X-ray density. Oneexception to this enrichment as illustrated in the referenceimages is flow line (or eutectic depletion), where there is alocal imp
25、overishment of the alloying elements that have a highX-ray density (see Note 3).a) eutectic segregationmicro shrinkage typetype ofsegregation develops when a micro shrinkage develops duringsolidification, and is fed with residual liquid rich in densealloying elements such as thorium. The area will s
26、how light ona radiographic image (see Note 3).b) eutectic segregationpipe shrink typetype of segrega-tion develops during solidification when a pipe shrink formsand is immediately filled with eutectic liquid rich in high X-raydensity alloying elements. The area shows light in a negativeimage as a fe
27、athery or dendritic feature (see Note 3).c) eutectic segregationhot tear typetype of segregationdevelops during solidification when the hot tear that takes placeis immediately filled with liquid rich in alloying elements highin X-ray density. The defect shows as white or light irregulardefined lines
28、 in a negative image (see Note 3).d) eutectic depletionflow linetype of segregation devel-ops when a section of a mold is filled by liquid and solidifiesat the front before liquid from another feed meets the solidfront.Aportion of the solid front then partially melts, otherwisethe discontinuity woul
29、d be a cold shut. Solidification beginsafter this remelt and the initial crystals are of high purity andcontain fewer high-density alloying elements than the meltaverage. Since the metal is still flowing across these crystals,the composition ahead of this solidifying front is depleted. Thisdepletion
30、 of the eutectic shows in a negative image as a darkdiffused line (see Note 3).e) oxide inclusions in magnesium alloys containingzirconiumshow on a radiograph as well defined light area ofirregular shape and size resembling a radiograph of a com-pacted fine steel wool. It is composed of complex magn
31、esiumoxide film with high zirconium content, and, if present, rareearths and thorium oxides also. It is often associated withzirconium-rich particles.3.2.13 shrinkage cavityappears as a dendritic, filamentary,or jagged darkened area in a negative image.3.2.14 shrinkage porosity or sponge (nonferrous
32、 alloys)alocalized lacy or honeycombed darkened area in a negativeimage.3.2.15 system resolutionthe detector-measured resolutiondivided by the geometric magnification.NOTE 2In the descriptions of terms above, references to darkness ofthe image refer to cases where the images are being reviewed in ne
33、gativeformat such that the images appear similar to the way the images wouldappear on film (that is, air or lower density materials show dark whilehigher density materials show as a lighter shade of gray). Where imagesare reviewed in positive format, the terms light or dark or lighter or darkerwill
34、need to be reversed.NOTE 3More detailed descriptions of these discontinuities can befound in the article referenced below5.4. Significance and Use4.1 These digital reference images are intended for refer-ence only, but are so designed that acceptance standards, whichmay be developed for particular r
35、equirements, can be specifiedin terms of these digital reference images. The illustrations aredigital images prepared from castings that were producedunder conditions designed to develop the discontinuities. Theimages of the14 in. (6.4 mm) castings are intended to be usedin the thickness range up to
36、 and including12 in. (12.7 mm).The images of the34 in. (19.1 mm) castings are intended to beused in the thickness range of over12 in. (12.7 mm), up to andincluding 2 in. (50.8 mm).4.2 Image DeteriorationMany conditions can affect theappearance and functionality of digital reference images. Forexampl
37、e, electrical interference, hardware incompatibilities,and corrupted files or drivers may affect their appearance. TheASTM E2002 line pair gauges located in the lower right handcorner of each digital reference can be used as an aid to detect5Lagowski, B.,“New Reference Radiographs for Magnesium Allo
38、y Castings,”Journal of Testing and Evaluation, Vol 2, No. 4, July 1974.E2869 172image deterioration by comparing the measured resolutionusing the gauges to the resolution stated on the digital referenceimage. Do not use the digital reference images if theirappearance has been adversely affected such
39、 that the interpre-tation and use of the images could be influenced.4.3 Agreement should be reached between cognizant engi-neering organization and the supplier that the system used bythe supplier is capable of detecting and classifying the requireddiscontinuities.5. Basis for Application5.1 The dig
40、ital reference images may be applied as accep-tance standards tailored to the end use of the product. Appli-cation of these digital reference images as acceptance standardsshould be based on the intended use of the product and thefollowing considerations (see Note 4).5.1.1 An area of like size to th
41、at of the digital referenceimage shall be the unit areas by which the production digitalimage is evaluated, and any such area shall meet the require-ments as defined for acceptability.5.1.2 Any combination or subset of these digital referenceimages may be used as is relevant to the particular applic
42、ation.Different grades or acceptance limits may be specified for eachdiscontinuity type. Furthermore, different grades may be speci-fied for different regions or zones of a component.5.1.3 Special considerations may be required where morethan one discontinuity type is present in the same area. Anymo
43、difications to the acceptance criteria required on the basis ofmultiple discontinuity types must be specified.5.1.4 Production digital images containing porosity, gas, orinclusions may be rated by the overall condition with regard tosize, number, and distribution. These factors should be consid-ered
44、 in balance.5.1.5 As a minimum, the acceptance criteria should containinformation addressing: zoning of the part (if applicable), theacceptance severity level for each discontinuity type, and thespecified area to which the digital reference images are to beapplied.NOTE 4Caution should be exercised i
45、n specifying the acceptancecriteria to be met in a casting. Casting design coupled with foundrypractice should be considered. It is advisable to consult with themanufacturer/foundry before establishing the acceptance criteria to ensurethe desired quality level can be achieved.6. Procedure for Evalua
46、tion6.1 Select the appropriate Digital Reference Image.6.2 Apply contrast adjustments to the reference image byeither method described in 9.5.6.3 Evaluation shall be performed against the adjustedreference image.7. Description7.1 The digital reference images listed in Table 1 illustrateeach type of
47、discontinuity in eight grades. The digital referenceimages listed in Table 2 illustrate each type of discontinuity ineight grades, with the exception of discrete discontinuities ofeutectic segregation, where only one example of pipe shrink,flow line, hot tear, and oxide inclusion is given. Although
48、eightgrades of each discontinuity are shown (with the aboveexceptions), a numerically smaller graded set of discontinuitiesbased on these digital reference images could be used foracceptance standards. (See Note 5.)7.2 The alloys used to reproduce the various discontinuitiesare as listed in Table 3.
49、7.3 The step wedges shown in the digital reference imagesare made of AZ91E, EV31, WE43 or ZE41A magnesium withthe thickness of the steps listed in Table 4.NOTE 5Misruns, core shift, cold shut, and surface irregularities arenot illustrated, as they are readily identifiable by surface examination orby other means of nondestructive testing.8. Digital Image Installation Procedure8.1 Follow the instructions provided with the digital refer-ence images to load the reference image software.8.2 The software files will be saved to a default locationduri
