ASTM E1814-2014 Standard Practice for Computed Tomographic &40 CT&41 Examination of Castings《铸件计算机层析(CT)检查的标准实施规程》.pdf
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1、Designation: E1814 14Standard Practice forComputed Tomographic (CT) Examination of Castings1This standard is issued under the fixed designation E1814; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A num
2、ber in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This practice covers a uniform procedure for the exami-nation of castings by the computed tomography (CT) tech-nique. The requirements ex
3、pressed in this practice are intendedto control the quality of the nondestructive examination by CTand are not intended for controlling the acceptability or qualityof the castings. This practice implicitly suggests the use ofpenetrating radiation, specifically X rays and gamma rays.1.2 This practice
4、 provides a uniform procedure for a CTexamination of castings for one or more of the followingpurposes:1.2.1 Examining for discontinuities, such as porosity,inclusions, cracks, and shrink;1.2.2 Performing metrological measurements and determin-ing dimensional conformance; and1.2.3 Determining revers
5、e engineering data, that is, creatingcomputer-aided design (CAD) data files.1.3 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 determi
6、ne the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E543 Specification for Agencies Performing NondestructiveTestingE1316 Terminology for Nondestructive ExaminationsE1441 Guide for Computed Tomography (CT) ImagingE1570 Practice for Computed Tomogra
7、phic (CT) Examina-tionE1672 Guide for Computed Tomography (CT) System Se-lectionE1695 Test Method for Measurement of Computed Tomog-raphy (CT) System PerformanceE1935 Test Method for Calibrating and Measuring CTDensityE2339 Practice for Digital Imaging and Communication inNondestructive Evaluation (
8、DICONDE)E2767 Practice for Digital Imaging and Communication inNondestructive Evaluation (DICONDE) for X-ray Com-puted Tomography (CT) Test Methods2.2 ASNT Documents:3SNT-TC-1A Recommended Practice for Personnel Qualifi-cation and Certification in Nondestructive TestingANSI/ASNT CP-189 Standard for
9、Personnel Qualificationand Certification of Nondestructive Testing Personnel2.3 Military Standards:4NAS 410 Certification and Qualification of NondestructiveTest Personnel3. Terminology3.1 DefinitionsDefinitions of terms applicable to thispractice may be found in Terminology E1316 and GuideE1441.3.2
10、 Definitions of Terms Specific to This Standard:3.2.1 fixturingthe mounting hardware used to place theobject in the CT system.3.2.2 scan planscan locations and the system configura-tion parameters for a specific part examination.4. Significance and Use4.1 CT may be performed on an object when it is
11、in theas-cast, intermediate, or final machined condition. A CTexamination can be used as a design tool to improve wax formsand moldings, establish process parameters, randomly checkprocess control, perform final quality control (QC) examina-tion for the acceptance or rejection of parts, and analyzef
12、ailures and extend component lifetimes.4.2 The most common applications of CT for castings arefor the following: locating and characterizing discontinuities,1This practice is under the jurisdiction of ASTM Committee E07 on Nonde-structive Testing and is the direct responsibility of Subcommittee E07.
13、01 onRadiology (X and Gamma) Method.Current edition approved June 1, 2014. Published June 2014. Originallyapproved in 1996. Last previous edition approved in 2007 as E1814 - 96(2007).DOI: 10.1520/E1814-14.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer S
14、ervice at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available fromAmerican Society for Nondestructive Testing (ASNT), P.O. Box28518, 1711 Arlingate Ln., Columbus, OH 43228-0518, http:/www.asnt.org.4Available
15、 from Standardization Documents Order Desk, DODSSP, Bldg. 4,Section D, 700 Robbins Ave., Philadelphia, PA 19111-5098, http:/assist.daps.dla.mil.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 194
16、28-2959. United States1such as porosity, inclusions, cracks, and shrink; measuringas-cast part dimensions for comparison with design dimen-sions; and extracting dimensional measurements for reverseengineering.4.3 The extent to which a CT image reproduces an object ora feature within an object is dic
17、tated largely by the competinginfluences of spatial resolution, contrast discrimination, thespecific geometry and material of the object itself, and artifactsof the imaging system. Operating parameters strike an overallbalance between image quality, examination time, and cost.4.4 Artifacts are often
18、 the limiting factor in CT imagequality. (See Practice E1570 for an in-depth discussion ofartifacts.) Artifacts are reproducible features in an image thatare not related to actual features in the object. Artifacts can beconsidered correlated noise because they form repeatable fixedpatterns under giv
19、en conditions yet carry no object informa-tion. For castings, it is imperative to recognize what is and isnot an artifact since an artifact can obscure or masquerade as adiscontinuity.Artifacts are most prevalent in castings with longstraight edges or complex geometries, or both.5. Basis of Applicat
20、ion5.1 The following items shall be agreed upon between thepurchaser and the supplier and specified in the contract or joborder:5.1.1 Nondestructive Testing Agency EvaluationThe useof a nondestructive testing (NDT) agency, as defined inPractice E543. If a systematic assessment of the capability ofth
21、e agency is specified, a documented procedure, such as thatdescribed in Practice E543, should be used as the basis forevaluation.5.1.2 Personnel QualificationsAll CT examination per-sonnel shall be qualified and certified in accordance with awritten procedure conforming to ANSI/ASNT CP-189, SNT-TC-1
22、A, NAS 410, or a similar document. The written proce-dure shall include training that addresses CT issues specifically.5.1.3 General RequirementsGeneral requirements shall bespecified in accordance with Section 8:(1) written procedure,8.1; and (2) CT system validation measurements, 8.3.5.1.3.1 Speci
23、fic requirements regarding preparation and ap-proval of the written procedures should be agreed upon inadvance by the purchaser and the supplier.5.1.4 FixturingThe object fixturing shall be determinedby agreement between the purchaser and the supplier inaccordance with 9.2.5.1.5 Image ProcessingImag
24、e processing routines used inanalysis of the CT data shall be specified in accordance with6.2:(1) dimensional measurements, 6.2.1; and (2) discontinuitycharacterization, 6.2.2.5.1.6 Discontinuity TypesA listing of the expected kindsof discontinuities shall be provided or referenced, and theacceptanc
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