ASTM C1322-15(2019)
(Practice)Standard Practice for Fractography and Characterization of Fracture Origins in Advanced Ceramics
Standard Practice for Fractography and Characterization of Fracture Origins in Advanced Ceramics
SIGNIFICANCE AND USE
5.1 This practice is suitable for monolithic and some composite 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 fracture origins may not be possible due to the specific microstructure.
5.2 This practice is principally oriented towards characterization of fracture origins in specimens loaded in so-called fast fracture testing, but the approach can be extended to include other modes of loading as well.
5.3 The procedures described within are primarily applicable to mechanical test specimens, although the same procedures may be relevant to component fracture analyses as well. It is customary practice to test a number of specimens (constituting a sample) to permit statistical analysis of the variability of the material’s strength. It is usually not difficult to test the specimens in a manner that will facilitate subsequent fractographic analysis. This may not be the case with component fracture analyses. Component fracture analysis is sometimes aided by cutting test pieces from the component and fracturing the test pieces. Fracture markings and fracture origins from the latter may aid component interpretation.
5.4 Optimum fractographic analysis requires examination of as many similar specimens or components as possible. This will enhance the chances of successful interpretations. Examination of only one or a few specimens can be misleading. Of course, in some instances the fractographer may have access to only one or a few fractured specimens or components.
5.5 Successful and complete fractography also requires careful consideration of all ancillary information that may be available, such as microstructural characteristics, material fabrication, properties and service histories, component or specimen machining, or preparation techniques.
5.6 Fractographic inspection and analysis can b...
SCOPE
1.1 The objective of this practice is to provide an efficient and consistent methodology to locate and characterize fracture origins in advanced ceramics. It is applicable to advanced ceramics that are brittle; that is, fracture that takes place with little or no preceding plastic deformation. In such materials, fracture commences from a single location which is termed the fracture origin. The fracture origin in brittle ceramics normally consists of some irregularity or singularity in the material which acts as a stress concentrator. In the parlance of the engineer or scientist, these irregularities are termed flaws or defects. The latter word should not be construed to mean that the material has been prepared improperly or is somehow faulty.
1.2 Although this practice is primarily intended for laboratory test piece analysis, the general concepts and procedures may be applied to component fracture analyses as well. In many cases, component fracture analysis may be aided by cutting laboratory test pieces out of the component. Information gleaned from testing the laboratory pieces (for example, flaw types, general fracture features, fracture mirror constants) may then aid interpretation of component fractures. For more information on component fracture analysis, see Refs (1, 2).2
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
General Information
Relations
Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: C1322 − 15 (Reapproved 2019)
Standard Practice for
Fractography and Characterization of Fracture Origins in
Advanced Ceramics
This standard is issued under the fixed designation C1322; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Referenced Documents
1.1 The objective of this practice is to provide an efficient 2.1 ASTM Standards:
and consistent methodology to locate and characterize fracture C162Terminology of Glass and Glass Products
origins in advanced ceramics. It is applicable to advanced C242Terminology of Ceramic Whitewares and Related
ceramics that are brittle; that is, fracture that takes place with Products
little or no preceding plastic deformation. In such materials, C1036Specification for Flat Glass
fracturecommencesfromasinglelocationwhichistermedthe C1145Terminology of Advanced Ceramics
fractureorigin.Thefractureorigininbrittleceramicsnormally C1161Test Method for Flexural Strength of Advanced
consists of some irregularity or singularity in the material Ceramics at Ambient Temperature
which acts as a stress concentrator. In the parlance of the C1211Test Method for Flexural Strength of Advanced
engineer or scientist, these irregularities are termed flaws or Ceramics at Elevated Temperatures
defects. The latter word should not be construed to mean that C1239Practice for Reporting Uniaxial Strength Data and
the material has been prepared improperly or is somehow EstimatingWeibull Distribution Parameters forAdvanced
faulty. Ceramics
C1499Test Method for Monotonic Equibiaxial Flexural
1.2 Although this practice is primarily intended for labora-
Strength of Advanced Ceramics at Ambient Temperature
tory test piece analysis, the general concepts and procedures
C1678Practice for Fractographic Analysis of Fracture Mir-
may be applied to component fracture analyses as well. In
ror Sizes in Ceramics and Glasses
many cases, component fracture analysis may be aided by
F109Terminology Relating to Surface Imperfections on
cutting laboratory test pieces out of the component. Informa-
Ceramics
tion gleaned from testing the laboratory pieces (for example,
2.2 NIST Standard:
flaw types, general fracture features, fracture mirror constants)
NIST Special Publication SP 960-16Guide to Practice for
may then aid interpretation of component fractures. For more
Fractography of Ceramics and Glasses (2)
information on component fracture analysis, see Refs (1, 2).
2.3 CEN Standard:
1.3 This standard does not purport to address all of the
EN 843-6 Advanced Technical Ceramics—Mechanical
safety concerns, if any, associated with its use. It is the
Properties of Monolithic Ceramics at Room
responsibility of the user of this standard to establish appro-
Temperature—Part 6: Guidance for Fractographic Inves-
priate safety, health, and environmental practices and deter-
tigation
mine the applicability of regulatory limitations prior to use.
1.4 This international standard was developed in accor-
3. Terminology
dance with internationally recognized principles on standard-
3.1 Definitions:
ization established in the Decision on Principles for the
3.1.1 General—Thefollowingtermsaregivenasabasisfor
Development of International Standards, Guides and Recom-
identifying fracture origins in advanced ceramics. It should be
mendations issued by the World Trade Organization Technical
recognized that origins can manifest themselves differently in
Barriers to Trade (TBT) Committee.
1 3
This practice is under the jurisdiction ofASTM Committee C28 on Advanced For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Ceramics and is the direct responsibility of Subcommittee C28.01 on Mechanical contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Properties and Performance. Standards volume information, refer to the standard’s Document Summary page on
CurrenteditionapprovedJuly1,2019.PublishedJuly2019.Originallyapproved the ASTM website.
in 1996. Last previous edition approved in 2015 as C1322–15. DOI: 10.1520/ Available from National Institute of Standards and Technology (NIST), 100
C1322-15R19. Bureau Dr., Stop 1070, Gaithersburg, MD 20899-1070, http://www.nist.gov.
2 5
Theboldfacenumbersinparenthesesrefertothelistofreferencesattheendof Available from European Committee for Standardization (CEN), Avenue
this standard. Marnix 17, B-1000, Brussels, Belgium, http://www.cen.eu.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C1322 − 15 (2019)
various materials. The photographs in Appendix X1 show 3.2.3 crack (CK), n—as used in fractography, a volume- or
examples of the origins defined in 3.2.1 and 3.2.12.Terms that surface-distributed flaw that is a surface of fracture without
are contained in otherASTM standards are noted at the end of complete separation. C1145
the each definition. The specific origin types listed in 3.2.1 –
3.2.4 handling damage (HD), n—as used in fractography,
3.2.12 are the most common types in advanced ceramics, but
surface-distributed flaws that include scratches, chips, cracks,
by no means cover all possibilities. NIST Special Publication
etc., due to the handling of the specimen/component. C1145
SP960-16 (2)includesmanymoreorigintypes.Subsection3.3
3.2.5 inclusion (I), n—as used in fractography, a volume-
providesguidanceonhowtocharacterizeordefineotherorigin
distributed flaw that is a foreign body that has a composition
types. Some common origin types are identified in 3.2.1 –
different from the nominal composition of the bulk advanced
3.2.12. These origin flaws are distributed throughout the bulk
ceramic. C1145
(inherentlyvolumedistributed)oraredistributedonanexterior
3.2.6 large grain(s) (LG), n—as used in fractography, a
surface (inherently surface distributed). The distinction is very
important for Weibull statistical analysis and size scaling of volume- or surface-distributed flaw that is a single (or cluster
of) grain(s) having a size significantly greater than that
strength as discussed in Practice C1239. Subsection 7.2 pro-
vides guidance on interpretation encompassed by the normal grain size distribution. C1145
3.1.2 advanced ceramic, n—a highly engineered, high-
3.2.7 machining damage (MD), n—as used in fractography,
performance, predominately nonmetallic, inorganic, ceramic
a surface-distributed flaw that is a microcrack(s), chip(s),
material having specific functional attributes. C1145
striation(s), or scratch(es), or a combination of these, created
during the machining process.
3.1.3 brittle fracture, n—fracture that takes place with little
or no preceding plastic deformation. 3.2.7.1 Discussion—Machining may result in the formation
of surface or subsurface damage, or both. C1145
3.1.4 flaw, n—structural discontinuity in an advanced ce-
3.2.8 pit (PT), n—as used in fractography, a surface-
ramic body that acts as a highly localized stress raiser.
distributed flaw that is a cavity created on the specimen/
3.1.4.1 Discussion—The presence of such discontinuities
component surface during the reaction/interaction between the
does not necessarily imply that the ceramic has been prepared
material and the environment, for example, corrosion or
improperly or is faulty.
oxidation. C1145
3.1.5 fractography, n—means and methods for characteriz-
3.2.9 pore (P(V)), n—as used in fractography, a volume-
ing a fractured specimen or component. C1145
distributed flaw that is a discrete cavity or void in a solid
3.1.6 fracture mirror, n—as used in fractography of brittle
material. C1145
materials, a relatively smooth region in the immediate vicinity
3.2.10 porous region (PR), n—as used in fractography, a
of and surrounding the fracture origin.
volume-distributed flaw that is a three-dimensional zone of
3.1.7 fracture origin, n—the source from which brittle
porosity or microporosity. C1145
fracture commences. C1145
3.2.11 porous seam (PS), n—as used in fractography, a
3.1.8 grain boundary (GB), n—as used in fractography, a
volume-distributed flaw that is a two-dimensional area of
volume-distributed flaw that is a boundary facet between two
porosity or microporosity. C1145
or more grains.
3.2.12 surface void (SV), n—as used in fractography, a
3.1.8.1 Discussion—This flaw is most apt to be strength
surface-distributed flaw that is a cavity created at the surface/
limiting in coarse-grained ceramics.
exterior as a consequence of the reaction/interaction between
3.1.9 hackle, n—as used in fractography, a line or lines on
the material and the processing environment, for example,
the crack surface running in the local direction of cracking,
surface reaction layer or bubble that is trapped during
separating parallel but non-coplanar portions of the crack
processing. C1145
surface.
3.3 Miscellaneous Origins:
3.1.10 mist, n—as used in fractography of brittle materials,
3.3.1 unidentified origin (?), n—as used in this practice, an
markings on the surface of an accelerating crack close to its
uncertain or undetermined fracture origin.
effective terminal velocity, observable first as a misty appear-
3.4 Other terms or fracture origin types may be devised by
ance and with increasing velocity reveals a fibrous texture,
the user if those listed in 3.2.1 – 3.2.12 are inadequate. In such
elongated in the direction of crack propagation.
instances, the user shall explicitly define the nature of the
3.2 Common Origins:
fracture origin (flaw) and whether it is inherently volume or
3.2.1 agglomerate (A), n—as used in fractography, a
surface distributed.Additional terms for surface imperfections
volume-distributed flaw that is a cluster of grains, particles,
can be found inTerminology F109 and supplementary fracture
platelets, or whiskers, or a combination thereof, present in a
origin types for ceramics and glasses may be found in
larger solid mass. C1145
Terminologies C162 and C242 and in Specification C1036.
3.2.2 compositional inhomogeneity (CI), n—as used in Examples of additional terms are hard agglomerate, collapsed
fractography, a volume-distributed flaw that is a microstruc- agglomerate, hard agglomerate (CEN 843-6) poorly bonded
tural irregularity related to the nonuniform distribution of the region, glassy inclusion, chip, closed chip, chip (CEN 843-6),
primary constituents or an additive or second phase. C1145 delamination (CEN 843-6), grain boundary cracks, chatter
C1322 − 15 (2019)
cracks, sharp impact cracks, blunt impact cracks, C-cracks
(ballbearings),baselinemicrostructuralflaws(BMF),ormain-
stream microstructural flaws (MMF). See the “Guide to Prac-
tice for Fractography of Ceramics and Glasses” (2) for discus-
sion and examples.
3.5 Theword“surface”mayhavemultiplemeanings.Itmay
refer to the intrinsic spatial distribution of flaws. The word
“surface” also may refer to the exterior of a test specimen cut
fromabulkceramicorcomponent,oralternatively,theoriginal
surface of the component in the as-fired state. It is recom-
mended that the terms original-surface or as-processed surface
be used if appropriate.
4. Summary of Practice
4.1 Prior to testing, mark the specimen or component
orientation and location to aid in reconstruction of the
specimen/component fragments. Marker lines made with a
pencil or felt-tip marker may suffice. See Fig. 1.
4.2 Whenever possible, test the specimen(s)/component(s)
to fracture in a fashion that preserves the primary fracture
surface(s) and all associated fragments for further fracto-
graphic analysis.
4.3 Carefully handle and store the specimen(s)/
component(s)tominimizeadditionaldamageorcontamination
of the fracture surface(s), or both.
4.4 Visuallyinspectthefracturedspecimen(s)/component(s)
(1 to 10×) in order to determine crack branching patterns, any
evidence of abnormal fracture patterns (indicative of testing
misalignments), the primary fracture surfaces, the location of
the mirror and, if possible, the fracture origin. Specimen/
component reconstruction may be helpful in this step. Label
the pieces with a letter or numerical code and photograph the
assembly if appropriate.
4.5 Useanopticalmicroscope(10to200×)toexamineboth
matinghalvesoftheprimaryfracturesurfaceinordertolocate
and, if possible, characterize the origin. Repeat the examina-
tion of pieces as required. If the fracture origin cannot be
characterized, then conduct the optical examination with the
purpose 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 or
machining damage or any interactions that may have occurred
Keep appropriate records, digital images, and photographs at each step to
between these surfaces and the environment.
assist in the origin characterization and for future reference.
4.7 Clean and prepare the specimen(s)/component(s) for
SEM examination, if necessary.
FIG. 1 Simplified Schematic Diagram of the Fractographic Analy-
4.8 Carry out SEM examination (10 to 2000×) of both sis Procedure
mating halves of the primary fracture surface.
4.9 Characterize the strength-limiting origin by its identity,
location and the general features of the fractured specimen/
location,andsize.Whenappropriate,usethechemicalanalysis
component, as well as for future reference.
capability of the SEM to help characterize the origin.
4.12 Compare the measured origin size to that estimated by
4.10 If necessary, repeat 4.6 using the SEM.
fracturemechanics.Ifthesesizesarenotingeneralagreement,
4.11 Keep appropriate records, digital images, and photo- then an explanation shall be given to account for the discrep-
graphs at each step in order to characterize the origin, show its ancy.
C1322 − 15 (2019)
4.13 For a new material, or a new set of processing or 5.8 The irregularities which act as fracture origins in ad-
exposureconditions,itishighlyrecommendedthatarepresen- vanced ceramics can develop during or after fabrication of the
tative polished section of the microstructure be photographed material.Largeirregularities(relativetotheaveragesizeofthe
to show the normal microstructural features such as grain size, microstructural features) such as pores, agglomerates, and
porosity, and phase distribution. inclusions are typically introduced during processing and can
(in one sens
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