1、Designation: E2869 13Standard 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. Scope1.1 These digital reference images illustrate the types anddegrees of discontinuities that may be found in magnesium-alloy castings. The castings illustrated
3、 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 a
5、nd 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 th
6、e 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 and health practices and determine the applica-bility of re
8、gulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E155 Reference Radiographs for Inspection of Aluminumand Magnesium CastingsE1316 Terminology for Nondestructive ExaminationsE2002 Practice for Determining Total Image Unsharpness inRadiologyE2446 Practice for Classification
9、 of Computed RadiologySystemsE2597 Practice for Manufacturing Characterization of Digi-tal Detector Arrays2.2 SMPTE Practice3RP133 SMPTE Recommended Practice Specifications forMedical Diagnostic Imaging Test Pattern for TelevisionMonitors and Hard-Copy Recording Cameras2.3 ASTM Adjuncts4Digital Refe
10、rence Images for Magnesium Castings3. Terminology3.1 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 ra
11、diologicalappearance. (See Note 2.)3.2.2 aliasingartifacts 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 o
12、f contrastbetween the production image and the reference 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-structi
13、ve Testing and is the direct responsibility of Subcommittee E07.02 onReference Radiological Images.Current edition approved June 1, 2013. Published August 2013. DOI: 10.1520/E286913.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.o
14、rg. 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/4Available from ASTM International He
15、adquarters. Order Adjunct No.RRE2869. Original adjunct produced in 2013.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.2.5 foreign materialsappear as isolated, irregular, orelongated variations in brightness, not corresponding to v
16、aria-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, smooth-edged dark spots in a negative image, occurring individually, inclusters, or distributed throughout the
17、 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 resolutionthe characteristic resolution of adigital radiographic system as measured in accordance with8.5.3.2.9 micro
18、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 more massive andequiaxed than the feathery type.3.2.11 reacted sand inclusionsappear as “spottysegregation,” w
19、hich 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 reaction with molten magnesium alloys con-taining zirconium (see Note 3).3.2.12 segregationsappear as variations in i
20、magedarkness, 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 range from a mottling-type effect throughwhite-diffused spots blending with the matrix, to a cloud-likeappearance
21、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 when a defect or discontinuity develops duringsolidification and is fed with a near eutectic residual liquid ri
22、chwith 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 impoverishment of the alloying elements that have a highX-ray density (see Note 3).a) eutectic segregationmicro s
23、hrinkage 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 show light ona radiographic image (see Note 3).b) eutectic segregationpipe shrink typetype of segrega-tion deve
24、lops 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 feathery or dendritic feature (see Note 3).c) eutectic segregationhot tear typetype of segregationdevelops durin
25、g 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 in a negative image (see Note 3).d) eutectic depletionflow linetype of segregation devel-ops when a section o
26、f 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 would be a cold shut. Solidification beginsafter this remelt and the initial crystals are of high purity andcontai
27、n 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 of the eutectic shows in a negative image as a darkdiffused line (see Note 3).e) oxide inclusions in magnesiu
28、m 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 magnesiumoxide film with high zirconium content, and, if present, rareearths and thorium oxides also. It is often
29、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 alloys)alocalized lacy or honeycombed darkened area in a negativeimage.3.2.15 system resolutionthe detector-m
30、easured 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 negativeformat such that the images appear similar to the way the images wouldappear on film (that is, air or lo
31、wer 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 need to be reversed.NOTE 3More detailed descriptions of these discontinuities can befound in the article refer
32、enced 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 requirements, can be specifiedin terms of these digital reference images. The illustrations aredigital images p
33、repared 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 and including12 in. (12.7 mm).The images of the34 in. (19.1 mm) castings are intended to beused in the thickn
34、ess 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. Forexample, electrical interference, hardware incompatibilities,and corrupted files or drivers may affect their appeara
35、nce. 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 Alloy Castings,”Journal of Testing and Evaluation, Vol 2, No. 4, July 1974.E2869 132image deterioration by compari
36、ng 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 that the interpre-tation and use of the images could be influenced.4.3 Agreement should be reached between co
37、gnizant 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 digital reference images may be applied as accep-tance standards tailored to the end use of the product. Appli-ca
38、tion 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 that of the digital referenceimage shall be the unit areas by which the production digitalimage is evaluated, an
39、d 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 application.Different grades or acceptance limits may be specified for eachdiscontinuity type. Furthermore, differen
40、t 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. Anymodifications to the acceptance criteria required on the basis ofmultiple discontinuity types must be specified.
41、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 in balance.5.1.5 As a minimum, the acceptance criteria should containinformation addressing: zoning of the pa
42、rt (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 in specifying the acceptancecriteria to be met in a casting. Casting design coupled with foundrypractice should
43、 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 Evaluation6.1 Select the appropriate Digital Reference Image.6.2 Apply contrast adjustments to the reference image b
44、yeither 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 discontinuity in eight grades. The digital referenceimages listed in Table 2 illustrate each type of discontin
45、uity 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 eightgrades of each discontinuity are shown (with the aboveexceptions), a numerically smaller graded set of di
46、scontinuitiesbased 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 3.7.3 The step wedges shown in the digital reference imagesare made of AZ91E, EV31, WE43 or ZE41A magnesium with
47、the 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 prov
48、ided with the digital refer-ence images to load the reference image software.8.2 The software files will be saved to a default locationduring installation unless instructed otherwise during the loadprocess.8.3 The software will require the user to specify either apositive or negative image. Select t
49、he option to match theviewing format (positive or negative image) of the systemsviewing software.8.4 The software load process will require the digitalreference image resolution to be specified to the nearest10-micron increment. Select the resolution that will mostclosely match the system resolution. System resolution is thedetector resolution divided by the geometric magnification tobe used during examination. (See Note 6.)8.5 Determine the detector resolution for digital detectorarrays (DDA) as described in Practice E2597 and for CRsystems i
