1、Designation: C 1322 05bStandard Practice forFractography and Characterization of Fracture Origins inAdvanced Ceramics1This standard is issued under the fixed designation C 1322; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the y
2、ear 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.1. Scope1.1 The objective of this practice is to provide an efficientand consistent methodology to locate and characterize
3、 fractureorigins in advanced ceramics. It is applicable to advancedceramics which are brittle; that is, the material adheres toHookes Law up to fracture. In such materials, fracturecommences from a single location which is termed the fractureorigin. The fracture origin in brittle ceramics normally c
4、onsistsof some irregularity or singularity in the material which acts asa stress concentrator. In the parlance of the engineer orscientist, these irregularities are termed flaws or defects. Thelatter should not be construed to mean that the material hasbeen prepared improperly or is somehow faulty.1
5、.2 Although this practice is primarily intended for labora-tory test piece analysis, the general concepts and proceduresmay be applied to component failure analyses as well. In manycases, component failure analysis may be aided by cuttinglaboratory test pieces out of the component. Informationgleane
6、d from testing the laboratory pieces (for example, flawtypes, general fracture features, fracture mirror constants) maythen aid interpretation of component fractures. For moreinformation on component fracture analysis, see Ref (1).21.3 This practice supersedes Military Handbook 790.1.4 This standard
7、 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 regulatory limitations prior to use.2. Referenced Documents2.1 ASTM
8、Standards:3C 162 Terminology of Glass and Glass ProductsC 242 Terminology of Ceramic Whitewares and RelatedProductsC 1036 Specification for Flat GlassC 1145 Terminology of Advanced CeramicsC 1161 Test Method for Flexural Strength of AdvancedCeramics at Ambient TemperatureC 1211 Test Method for Flexu
9、ral Strength of AdvancedCeramics at Elevated TemperaturesC 1239 Practice for Reporting Uniaxial Strength Data andEstimating Weibull Distribution Parameters for AdvancedCeramicsF 109 Terminology Relating to Surface Imperfections onCeramics2.2 Military Standard:4Military Handbook 790, Fractography and
10、 Characterizationof Fracture Origins in Advanced Structural Ceramics,19923. Terminology3.1 GeneralThe following terms are given as a basis foridentifying fracture origins that are common to advancedceramics. It should be recognized that origins can manifestthemselves differently in various materials
11、. The photographs inAppendix X1 show examples of the origins defined in 3.11 and3.20. Terms that are contained in other ASTM standards arenoted at the end of the each definition.3.2 advanced ceramic, na highly engineered, high-performance, predominately nonmetallic, inorganic, ceramicmaterial having
12、 specific functional attributes. C 11453.3 brittle fracture, nfracture that takes place with little orno preceding plastic deformation.3.4 flaw, nstructural discontinuity in an advanced ceramicbody that acts as a highly localized stress raiser.NOTE 1The presence of such discontinuities does not nece
13、ssarilyimply that the ceramic has been prepared improperly or is faulty.3.5 fractography, nmeans and methods for characterizinga fractured specimen or component. C 11451This practice is under the jurisdiction of ASTM Committee C28 on AdvancedCeramics and is the direct responsibility of Subcommittee
14、C28.02 on Reliability.Current edition approved July 1, 2005. Published July 2005. Originally approvedin 1996. Last previous edition approved in 2005 as C 1322 05a.2The boldface numbers in parentheses refer to the list of references at the end ofthis standard.3For referenced ASTM standards, visit the
15、 ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.4Available from Army Research Laboratory-Materials Directorate, AberdeenProving Ground, MD 21005.1Copy
16、right ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.6 fracture mirror, nas used in fractography of brittlematerials, a relatively smooth region in the immediate vicinityof and surrounding the fracture origin.3.7 fracture origin, nthe source
17、 from which brittle frac-ture commences. C 11453.8 grain boundary, n (GB)as used in fractography, avolume-distributed flaw that is a boundary facet between twoor more grains.NOTE 2This flaw is most apt to be strength limiting in course-grainedceramics.3.9 hackleas used in fractography, a line or lin
18、es on thecrack surface running in the local direction of cracking,separating parallel but non-coplanar portions of the cracksurface.3.10 mist, nas used in fractography of brittle materials,markings on the surface of an accelerating crack close to itseffective terminal velocity, observable first as a
19、 misty appear-ance and with increasing velocity reveals a fibrous texture,elongated in the direction of crack propagation.3.11 Inherently Volume-Distributed Origins:3.12 agglomerate, n, (A)as used in fractography, avolume-distributed flaw that is a cluster of grains, particles,platelets, or whiskers
20、, or a combination thereof, present in alarger solid mass. C 11453.13 compositional inhomogeneity, n, (CI)as used in frac-tography, a volume-distributed flaw that is a microstructuralirregularity related to the nonuniform distribution of theprimary constituents or an additive or second phase. C 1145
21、3.14 crack, n, (CK)as used in fractography, a volume- orsurface-distributed flaw that is a surface of fracture withoutcomplete separation. C 11453.15 inclusion, n, (I)as used in fractography, a volume-distributed flaw that is a foreign body that has a compositiondifferent from the nominal compositio
22、n of the bulk advancedceramic. C 11453.16 large grain(s), n, (LG)as used in fractography, avolume- or surface-distributed flaw that is a single (or clusterof) grain(s) having a size significantly greater than thatencompassed by the normal grain size distribution. C 11453.17 pore, n, (P(V)as used in
23、fractography, a volume-distributed flaw that is a discrete cavity or void in a solidmaterial. C 11453.18 porous region, n, (PR)as used in fractography, avolume-distributed flaw that is a 3-dimensional zone of poros-ity or microporosity. C 11453.19 porous seam, n, (PS)as used in fractography, avolume
24、-distributed flaw that is a 2-dimensional area of porosityor microporosity. C 11453.20 Inherently Surface-Distributed Origins:3.21 handling damage, n, (HD)as used in fractography,surface-distributed flaws that include scratches, chips, cracks,etc., due to the handling of the specimen/component. C 11
25、453.22 machining damage, n, (MD)as used in fractography,a surface-distributed flaw that is a microcrack(s), chip(s),striation(s), or scratch(es), or a combination of these, createdduring the machining process.NOTE 3Machining may result in the formation of surface or subsur-face damage, or both.3.23
26、pit, n, (PT)as used in fractography, a surface-distributed flaw that is a cavity created on the specimen/component surface during the reaction/interaction between thematerial and the environment, for example, corrosion oroxidation. C 11453.24 surface void, n, (SV)as used in fractography, asurface-di
27、stributed flaw that is a cavity created at the surface/exterior as a consequence of the reaction/interaction betweenthe material and the processing environment, for example,surface reaction layer or bubble that is trapped during process-ing.3.25 Miscellaneous Origins:3.26 unidentified origin, n, (?)
28、as used in this practice, anuncertain or undetermined fracture origin.3.27 Other terms or fracture origin types may be devised bythe user if those listed in 3.11 and 3.20 are inadequate. In suchinstances the user shall explicitly define the nature of thefracture origin (flaw) and whether it is inher
29、ently volume- orsurface-distributed. Additional terms for surface imperfectionscan be found in Terminology F 109 and supplementary fractureorigin types for ceramics and glasses may be found in TheCeramic Glossary5and Terminology C 162 and TerminologyC 242 and in a Specification C 1036. Examples of a
30、dditionalterms are hard agglomerate, collapsed agglomerate, poorlybonded region, glassy inclusion, chip, or closed chip.3.28 The word “surface” may have multiple meanings. Inthe definitions above, it refers to the intrinsic spatial distribu-tion of flaws. The word “surface” also may refer to the ext
31、eriorof a test specimen cut from a bulk ceramic or component, oralternatively, the original surface of the component in theas-fired state. It is recommended that the terms original-surfaceor as-processed surface be used if appropriate.4. Summary of Practice4.1 Prior to testing mark the specimen or c
32、omponent orien-tation and location to aid in reconstruction of the specimen/component fragments. Marker lines made with a pencil or felttip marker may suffice.4.2 Whenever possible, test the specimen(s)/component(s)to failure in a fashion that preserves the primary fracturesurface(s) and all associa
33、ted fragments for further fracto-graphic analysis.4.3 Carefully handle and store the specimen(s)/component(s) to minimize additional damage or contaminationof the fracture surface(s), or both.4.4 Visually inspect the fractured specimen(s)/component(s)(1 to 103) in order to determine crack branching
34、patterns, anyevidence of abnormal failure patterns (indicative of testingmisalignments), the primary fracture surfaces, the location ofthe mirror and, if possible, the fracture origin. Specimen/component reconstruction may be helpful in this step. Labelthe pieces with a letter or numerical code and
35、photograph theassembly if appropriate.4.5 Use an optical microscope (10 to 2003) to examineboth mating halves of the primary fracture surface in order tolocate and, if possible, characterize the origin. Repeat the5The American Ceramic Society, Westerville, OH 1984.C 1322 05b2examination of pieces as
36、 required. If the fracture origin cannotbe characterized, then conduct the optical examination with thepurpose of expediting subsequent examination with the scan-ning electron microscope (SEM).4.6 Inspect the external surfaces of the specimen(s)/component(s) near the origin for evidence of handling
37、ormachining damage or any interactions that may have occurredbetween these surfaces and the environment.4.7 Clean and prepare the specimen(s)/component(s) forSEM examination, if necessary.4.8 Carry out SEM examination (10 to 20003) of bothmating halves of the primary fracture surface.4.9 Characteriz
38、e the strength-limiting origin by its identity,location, and size. When appropriate, use the chemical analysiscapability of the SEM to help characterize the origin.4.10 If necessary, repeat 4.6 using the SEM.4.11 Keep appropriate records, digital images, and photo-graphs at each step in order to cha
39、racterize the origin, show itslocation and the general features of the fractured specimen/component, as well as for future reference.4.12 Compare the measured origin size to that estimated byfracture mechanics. If these sizes are not in general agreementthen an explanation shall be given to account
40、for the discrep-ancy.4.13 For a new material, or a new set of processing orexposure conditions, it is highly recommended that a represen-tative polished section of the microstructure be photographedto show the normal microstructural features such as grain sizeand porosity.5. Significance and Use5.1
41、This practice is suitable for monolithic and some com-posite ceramics, for example, particulate- and whisker-reinforced and continuous-grain-boundary phase ceramics.(Long- or continuous-fiber reinforced ceramics are excluded.)For some materials, the location and identification of fractureorigins may
42、 not be possible due to the specific microstructure.5.2 This practice is principally oriented towards character-ization of fracture origins in specimens loaded in so-called fastfracture testing, but the approach can be extended to includeother modes of loading as well.5.3 The procedures described wi
43、thin are primarily appli-cable to mechanical test specimens, although the same proce-dures may be relevant to component failure analyses as well. Itis customary practice to test a number of specimens (consti-tuting a sample) to permit statistical analysis of the variabilityof the materials strength.
44、 It is usually not difficult to test thespecimens in a manner that will facilitate subsequent fracto-graphic analysis. This may not be the case with componentfailure analyses. Component failure analysis is sometimesaided by cutting test pieces from the component and fracturingthe test pieces. Fractu
45、re markings and fracture origins from thelatter may aid component interpretation.5.4 Optimum fractographic analysis requires examination ofas many similar specimens or components as possible. Thiswill enhance the chances of successful interpretations. Exami-nation of only one or a few specimens can
46、be misleading. Ofcourse, in some instances the fractographer may have access toonly one or a few fractured specimens or components.5.5 Successful and complete fractography also requirescareful consideration of all ancillary information that may beavailable, such as microstructural characteristics, m
47、aterialfabrication, properties and service histories, component orspecimen machining, or preparation techniques.5.6 Fractographic inspection and analysis can be a time-consuming process. Experience will in general enhance theNOTEKeep appropriate records, digital images, and photographs ateach step t
48、o assist in the origin characterization and for future reference.FIG. 1 Simplified Schematic Diagram of the FractographicAnalysis ProcedureC 1322 05b3chances of correct interpretation and characterization, but willnot obviate the need for time and patience. Repeat examina-tions are often fruitful. F
49、or example, a particular origin type orkey feature may be overlooked in the first few test pieces of asample set.As the fractographer gains experience by looking atmultiple examples, he or she may begin to appreciate some keyfeature that was initially overlooked.5.7 This practice is applicable to quality control, materialsresearch and development, and design. It will also serve as abridge between mechanical testing standards and statisticalanalysis practices to permit comprehensive interpretation ofdata for design. An important feature of this practice
