1、Designation: E2669 10Standard Digital Reference Images forTitanium Castings1This standard is issued under the fixed designation E2669; 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 parenthes
2、es indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 The digital reference images provided in the adjunct tothis standard illustrate various types and degrees of disconti-nuities occurring in titanium castin
3、gs.2Use of this standard forthe specification or grading of castings requires procurement ofthe adjunct digital reference images, which illustrate thediscontinuity types and severity levels. They are intended toprovide the following:1.1.1 A guide enabling recognition of titanium castingdiscontinuiti
4、es and their differentiation both as to type anddegree through digital radiographic examination.1.1.2 Example digital radiographic illustrations of disconti-nuities and a nomenclature for reference in acceptance stan-dards, specifications and drawings.1.2 The digital reference images consist of seve
5、nteen digitalfiles each illustrating eight grades of increasing severity. Thefiles illustrate seven common discontinuity types representingcasting sections up to 1-in. (25.4-mm).1.3 The reference radiographs were developed for castingsections up to 1 in. (25.4 mm) in thickness.1.4 All areas of this
6、standard may be open to agreementbetween the cognizant engineering organization and the sup-plier, or specific direction from the cognizant engineeringorganization. These items should be addressed in the purchaseorder or the contract.NOTE 1Each of the digital reference images contain an image of ast
7、ep wedge and two duplex-wire gauges. Refer to Practice E2002 for wirepair details.1.5 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.1.6
8、 These digital reference images are not intended toillustrate the types or degrees of discontinuities when perform-ing film radiography. If performing film radiography of tita-nium castings, refer to Reference Radiographs E1320.1.7 This standard does not purport to address all of thesafety concerns,
9、 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 regulatory limitations prior to use.1.8 Only licensed copies of the software and images shall beutilized for production ins
10、pection. A copy of the ASTM/Userlicense agreement shall be kept on file for audit purposes.2. Referenced Documents2.1 ASTM Standards:3E94 Guide for Radiographic ExaminationE1025 Practice for Design, Manufacture, and MaterialGrouping Classification of Hole-Type Image Quality Indi-cators (IQI) Used fo
11、r RadiologyE1316 Terminology for Nondestructive ExaminationsE1320 Reference Radiographs for Titanium CastingsE2002 Practice for Determining Total Image Unsharpnessin RadiologyE2597 Practice for Manufacturing Characterization of Digi-tal Detector Arrays2.2 SMPTE Practice:4RP1332.3 ASTM Adjuncts:Digit
12、al Reference Images of Investment Steel Castings forAerospace Applications53. 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 refe
13、rence images are described based upon radiographicappearance when viewed in the negative polarity such that theimages appear in the same sense as they would when viewedon X-ray film. If images are viewed in the positive polarity, theterms lighter and darker will need to be reversed.1This standard is
14、 under the jurisdiction of ASTM Committee E07 on Nonde-structive Testing and is the direct responsibility of Subcommittee E07.02 onReference Radiological Images.Current edition approved Jan. 1, 2010. Published February 2010.2The digital reference images are considered to be applicable to all titaniu
15、mcastings, requiring close tolerances. Castings for which these images are applicablegenerally include those made by the lost wax, frozen mercury, ceramicast or shellmold processes.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.or
16、g. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.4Available from Society of Motion Picture and Television Engineers, 3 BarkerAvenue, White Plains, NY 10601; or www.smpte.org/smpte_store/5Available from ASTM International Headquar
17、ters. Order Adjunct No.RRE2669.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.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
18、 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 reference image thatmakes the change in digital driving level versus change inthickness equal for both images.3.2.4 DDLdigital driving level a
19、lso known as monitorpixel value.3.2.5 system resolutionthe detector-measured resolutiondivided by the geometric magnification.3.2.6 gasGas in its various forms is usually caused by thereaction of molten titanium with the mold or residual materialleft in the mold. Gas tends to migrate to the upper po
20、rtions ofthe casting. The formation of clustered or scattered gas holesresults from the generation of larger amounts of gas than asingle gas hole. Whether the larger amount of gas spreads outor is confined to a small area is dependent upon a number offactors including casting process, reaction area,
21、 solidificationrate, wall thickness, and geometry.3.2.6.1 gas holesspherical voids formed through the re-lease and subsequent entrapment of gas during solidification.Agas hole will appear as a dark round spot on the digital image.3.2.6.2 clustered gas holesa closely nested group of darkround voids c
22、oncentrated within a self-defined boundary area.3.2.6.3 scattered gas holesmultiple voids appearing asdark round spots on the digital image. They are randomlyspread throughout a part or area of a part to a lesser concen-tration than clustered gas holes but with the potential todegrade the casting th
23、rough their interaction which precludestheir evaluation on an individual basis.3.2.7 shrinkageWhile at times the appearance of shrink-age in titanium may be radiographically similar to shrinkage insteel, the faster solidification rate of titanium has a dramaticeffect on the conditions under which ea
24、ch shrinkage type willoccur in titanium. Other factors which influence the formationof shrinkage are wall thickness and thickness transition gradi-ents, gate size and orientation, mold design, casting configu-ration, metal/mold temperature, and pouring rate and method.All the types of shrinkage desc
25、ribed in 3.2.7.1 through 3.2.7.3have a degree of overlap. However, each is most likely to occurunder a specific set of conditions primarily influenced by metalfeed, section thickness and cooling rate.3.2.7.1 shrinkage cavityappears as a dark void withsmooth sides taking an appearance very similar to
26、 a gas hole.A shrinkage cavity, particularly in thicker wall sections, isusually larger than a single gas hole would be. The cavity isformed during the cooling process due to a lack of feedingmetal. The cavity compensates for the rapid solidificationtaking place at the surface of the casting, thereb
27、y forming thecavity in the center area of the wall. Shrinkage cavity has adefinite tendency to occur near hot spots where walls are12-in.(12.7-mm) thick or more.3.2.7.2 scattered shrinkageappears on a digital image asdark fine lacy or filamentary voids of varying densities. Thesevoids are usually un
28、iformly spread throughout the area of thecasting where shrinkage is occurring and are relatively shallow.3.2.7.3 shrinkage, centerlinecharacterized by a more dis-crete dark indication than scattered shrinkage. The indicationhas definite borders consisting of a lacy network of varyingdensity or a net
29、work of interconnected elongated voids. Cen-terline shrinkage is located primarily in the center of thematerial cross section with a tendency to orient toward gates orrisers.3.2.8 foreign material, less denseappear as dark indica-tions in a variety of shapes and sizes on a digital image.Inclusions m
30、ay be found in groups or appear singularly. Lessdense inclusions can be caused by contaminants in the moltentitanium, residual materials left on the surface of the mold, orbroken pieces of the mold becoming entrapped during solidi-fication.3.2.9 foreign material, more denseappear as light indica-tio
31、ns in a variety of shapes and sizes on a digital image. Moredense inclusions can be caused by contaminants introduced inthe same manner as less dense inclusions, or tungsten intro-duced during weld repairs.4. Significance and Use64.1 These digital reference images are intended for refer-ence only, b
32、ut are designed such that acceptance standards,which may be developed for particular requirements, can bespecified in terms of these digital reference images. Theillustrations are digital images of castings that were producedunder conditions designed to develop the discontinuities.4.1.1 Applicabilit
33、y of Thickness Designations:4.1.1.1 Clustered holes, scattered gas holes, scatteredshrinkage cavity, centerline shrinkage(1) The images of the14-in. (6.4-mm) castings are intendedto be used in the thickness range up to and including38-in.(9.5-mm). The images of the12-in. (12.7-mm) castings areintend
34、ed to be used in the thickness range of over38-in.(9.5-mm), up to and including58-in. (15.9-mm). The images ofthe34-in. (19.1-mm) castings are intended to be used in thethickness range of over58-in. (15.9-mm), up to and including1-in. (25.4-mm).4.1.1.2 Shrinkage Cavity:(1) The images of the12-in. (1
35、2.7-mm) castings areintended to be used in the thickness range up to and including58-in. (15.9-mm). The images of the34-in. (19.1-mm) castingsare intended to be used in the thickness range over58-in.(15.9-mm) to 1-in. (25.4-mm).4.1.1.3 Gas hole; foreign material, less dense; foreign ma-terial, more
36、dense(1) The images are intended to be used in the thicknessrange up to and including 1-in. (25.4-mm).4.2 Image DeteriorationMany conditions can affect theappearance and functionality of digital reference images. Forexample, electrical interference, hardware incompatibilities,and corrupted files and
37、 drivers may affect their appearance. The6A study was performed that compared film to digital modalities for theclassification of aluminum casting discontinuities. Results of this study are availablefrom ASTM as RR: E07-1004. A subsequent study was performed that comparedfilm to digital modalities f
38、or the classification of titanium and steel castingdiscontinuities. Results of this study are available from ASTM as RR:E07-1006.E2669 102Practice E2002 line pair gauges located in each digital refer-ence image can be used as an aid to detect image deteriorationby comparing the measured resolution u
39、sing the gauges to theresolution stated on the digital reference image. Do not use thedigital reference images if their appearance has been adverselyaffected such that the interpretation and use of the images couldbe influenced.4.3 Agreement should be reached between cognizant engi-neering organizat
40、ion and the supplier that the system used bythe supplier is capable of detecting and classifying the requireddiscontinuities.5. Basis of Application5.1 The digital reference images may be applied as accep-tance standards tailored to the end use of the product. Appli-cation of these digital reference
41、 images as acceptance standardsshould be based on the intended use of the product and thefollowing considerations (see Note 2).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, and any such area shall meet the
42、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, different grades may be speci-fied for
43、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.5.1.4 Production digital image
44、s containing gas or inclusionsmay be rated by the overall condition with regard to size,number, and distribution. These factors should be considered inbalance.5.1.5 As a minimum, the acceptance criteria should containinformation addressing: zoning of the part (if applicable), theacceptance severity
45、level for each discontinuity type, and thespecified area to which the digital reference images are to beapplied.NOTE 2Caution should be exercised in specifying the acceptancecriteria to be met in a casting. Casting design coupled with foundrypractice should be considered. It is advisable to consult
46、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 any necessary adjustments to the contrast of thereference image. Contrast adjustment may
47、 be conducted usinga process of contrast normalization between the productionimage and the reference image, or by an alternative processapproved by the cognizant engineering organization.6.3 If contrast normalization is used, perform the contrastnormalization (window width normalization) between the
48、 pro-duction image and the reference image as required by 9.5.6.3.1 Once the contrast normalization has been performed,contrast (window width) shall not be altered in either imagewithout re-performing contrast normalization prior to productevaluation. (See 9.5.)7. Description7.1 The digital referenc
49、e images listed in Table 1 illustrateeach type of graded discontinuity in eight grades. Althougheight grades of each discontinuity are shown, a numericallysmaller graded set of discontinuities based on these digitalreference images could be used for acceptance standards.7.2 The step wedges shown in the digital reference imagesare made of Titanium 6 Al 4V with the step thicknesses listedin Table 2.8. Digital Image Installation Procedure8.1 Follow the instructions provided with the digital refer-ence images to load the reference image software.8.2 The soft
