ASTM C1273-2018 Standard Test Method for Tensile Strength of Monolithic Advanced Ceramics at Ambient Temperatures.pdf

1、Designation: C1273 18Standard Test Method forTensile Strength of Monolithic Advanced Ceramics atAmbient Temperatures1This standard is issued under the fixed designation C1273; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the yea

2、r of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of tensilestrength under uniaxial loading of monolithic advanced ceram-

3、ics at ambient temperatures. This test method addresses, but isnot restricted to, various suggested test specimen geometries aslisted in the appendixes. In addition, test specimen fabricationmethods, testing modes (force, displacement, or strain control),testing rates (force rate, stress rate, displ

4、acement rate, or strainrate), allowable bending, and data collection and reportingprocedures are addressed. Note that tensile strength as used inthis test method refers to the tensile strength obtained underuniaxial loading.1.2 This test method applies primarily to advanced ceramicsthat macroscopica

5、lly exhibit isotropic, homogeneous, continu-ous behavior. While this test method applies primarily tomonolithic advanced ceramics, certain whisker- or particle-reinforced composite ceramics as well as certain discontinuousfiber-reinforced composite ceramics may also meet thesemacroscopic behavior as

6、sumptions. Generally, continuous fiberceramic composites (CFCCs) do not macroscopically exhibitisotropic, homogeneous, continuous behavior and applicationof this practice to these materials is not recommended.1.3 Values expressed in this test method are in accordancewith the International System of

7、Units (SI) and IEEE/ASTM SI10.1.4 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, health, and environmental practices and deter-mine the applicability of regul

8、atory limitations prior to use.Specific precautionary statements are given in Section 7.1.5 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards,

9、 Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2C1145 Terminology of Advanced CeramicsC1161 Test Method for Flexural Strength of AdvancedCeramics at Ambient TemperatureC1239 Practice for Reporti

10、ng Uniaxial Strength Data andEstimating Weibull Distribution Parameters for AdvancedCeramicsC1322 Practice for Fractography and Characterization ofFracture Origins in Advanced CeramicsD3379 Test Method for Tensile Strength andYoungs Modu-lus for High-Modulus Single-Filament MaterialsE4 Practices for

11、 Force Verification of Testing MachinesE6 Terminology Relating to Methods of Mechanical TestingE83 Practice for Verification and Classification of Exten-someter SystemsE337 Test Method for Measuring Humidity with a Psy-chrometer (the Measurement of Wet- and Dry-Bulb Tem-peratures)E1012 Practice for

12、Verification of Testing Frame and Speci-men Alignment Under Tensile and Compressive AxialForce ApplicationIEEE/ASTM SI 10 American National Standard for MetricPractice3. Terminology3.1 Definitions:3.1.1 The definitions of terms relating to tensile testingappearing in Terminology E6 apply to the term

13、s used in thistest method on tensile testing. The definitions of terms relatingto advanced ceramics testing appearing in Terminology C1145apply to the terms used in this test method. Pertinent definitionsas listed in Practice C1239, Practice E1012, TerminologyC1145, and Terminology E6 are shown in t

14、he following with1This test method is under the jurisdiction of ASTM Committee C28 onAdvanced Ceramics and is the direct responsibility of Subcommittee C28.01 onMechanical Properties and Performance.Current edition approved July 1, 2018. Published July 2018. Originally approvedin 1994. Last previous

15、 edition approved in 2015 as C1273 15. DOI: 10.1520/C1273-18.2For referenced ASTM standards, visit the 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.

16、Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of Inter

17、national Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1the appropriate source given in parentheses. Additional termsused in conjunction with this test method are defined in thefollowing:3.1.2 advanced ceramica highly enginee

18、red, high-performance, predominately nonmetallic, inorganic, ceramicmaterial having specific functional attributes. C11453.1.3 axial strain LL1, nthe average of longitudinalstrains measured at the surface on opposite sides of thelongitudinal axis of symmetry of the specimen by two strainsensing devi

19、ces located at the mid length of the reducedsection. E10123.1.4 bending strain LL1, nthe difference between thestrain at the surface and the axial strain. In general, the bendingstrain varies from point to point around and along the reducedsection of the specimen. E10123.1.5 breaking force F, nthe f

20、orce at which fractureoccurs. E63.1.6 fractographymeans and methods for characterizinga fractured specimen or component. C11453.1.7 fracture originthe source from which brittle fracturecommences. C11453.1.8 percent bendingthe bending strain times 100 dividedby the axial strain. E10123.1.9 slow crack

21、 growth (SCG)subcritical crack growth(extension) which may result from, but is not restricted to, suchmechanisms as environmentally assisted stress corrosion ordiffusive crack growth. C11453.1.10 tensile strength, SuFL2, nthe maximum tensilestress which a material is capable of sustaining. Tensilest

22、rength is calculated from the maximum force during a tensiontest carried to rupture and the original cross-sectional area ofthe specimen. E64. Significance and Use4.1 This test method may be used for material development,material comparison, quality assurance, characterization, anddesign data genera

23、tion.4.2 High-strength, monolithic advanced ceramic materialsgenerally characterized by small grain sizes (65 % relative humidity (RH) is not recommended, and anydeviations from this recommendation must be reported.5.2 Surface preparation of test specimens can introducefabrication flaws that may hav

24、e pronounced effects on tensilestrength. Machining damage introduced during test specimenC1273 182preparation can be either a random interfering factor in thedetermination of ultimate strength of pristine material (that is,increased frequency of surface initiated fractures compared tovolume initiate

25、d fractures), or an inherent part of the strengthcharacteristics to be measured. Surface preparation can alsolead to the introduction of residual stresses. Universal orstandardized test methods of surface preparation do not exist. Itshould be understood that final machining steps may or maynot negat

26、e machining damage introduced during the earlycoarse or intermediate machining. Thus, test specimen fabri-cation history may play an important role in the measuredstrength distributions and should be reported.5.3 Bending in uniaxial tensile tests can cause or promotenonuniform stress distributions w

27、ith maximum stresses occur-ring at the test specimen surface leading to non-representativefractures originating at surfaces or near geometrical transitions.In addition, if strains or deformations are measured at surfaceswhere maximum or minimum stresses occur, bending mayintroduce over or under meas

28、urement of strains. Similarly,fracture from surface flaws may be accentuated or muted by thepresence of the nonuniform stresses caused by bending.6. Apparatus6.1 Testing MachinesMachines used for tensile testingshall conform to the requirements of Practices E4. The forcesused in determining tensile

29、strength shall be accurate to within61 % at any force within the selected force range of the testingmachine as defined in Practices E4. A schematic showingpertinent features of the tensile testing apparatus is shown inFig. 1.6.2 Gripping Devices:6.2.1 GeneralVarious types of gripping devices may beu

30、sed to transmit the measured force applied by the testingmachine to the test specimens. The brittle nature of advancedceramics requires a uniform interface between the grip com-ponents and the gripped section of the test specimen. Line orpoint contacts and nonuniform pressure can produce Hertizan-ty

31、pe stresses, leading to crack initiation and fracture of the testspecimen in the gripped section. Gripping devices can beclassed generally as those employing active and those employ-ing passive grip interfaces as discussed in the followingsections.6.2.2 Active Grip InterfacesActive grip interfaces r

32、equirea continuous application of a mechanical, hydraulic, or pneu-matic force to transmit the force applied by the test machine tothe test specimen. Generally, these types of grip interfacescause a force to be applied normal to the surface of the grippedsection of the test specimen. Transmission of

33、 the uniaxial forceapplied by the test machine is then accomplished by frictionbetween the test specimen and the grip faces. Thus, importantaspects of active grip interfaces are uniform contact betweenthe gripped section of the test specimen and the grip faces andconstant coefficient of friction ove

34、r the grip/specimen inter-face.6.2.2.1 For cylindrical test specimens, a one-piece split-collet arrangement acts as the grip interface (1, 2)3as illus-trated in Fig. 2. Generally, close tolerances are required forconcentricity of both the grip and test specimen diameters. Inaddition, the diameter of

35、 the gripped section of the testspecimen and the unclamped, open diameter of the grip facesmust be within similarly close tolerances to promote uniformcontact at the test specimen/grip interface. Tolerances will varydepending on the exact configuration as shown in the appro-priate test specimen draw

36、ings.3The boldface numbers given in parentheses refer to a list of references at theend of the text.FIG. 1 Schematic Diagram of One Possible Apparatus for Con-ducting a Uniaxially Loaded Tensile TestFIG. 2 Example of a Smooth, Split-Collet Active Gripping Systemfor Cylindrical Test SpecimensC1273 18

37、36.2.2.2 For flat test specimens, flat-faced, wedge-grip facesact as the grip interface as illustrated in Fig. 3. Generally, closetolerances are required for the flatness and parallelism as wellas wedge angle of the grip faces. In addition, the thickness,flatness, and parallelism of the gripped sect

38、ion of the testspecimen must be within similarly close tolerances to promoteuniform contact at the test specimen/grip interface. Toleranceswill vary depending on the exact configuration as shown in theappropriate test specimen drawings.6.2.3 Passive Grip InterfacesPassive grip interfaces trans-mit t

39、he force applied by the test machine to the test specimenthrough a direct mechanical link. Generally, these mechanicallinks transmit the test forces to the test specimen via geometri-cal features of the test specimens such as button-head fillets,shank shoulders, or holes in the gripped head. Thus, t

40、heimportant aspect of passive grip interfaces is uniform contactbetween the gripped section of the test specimen and the gripfaces.6.2.3.1 For cylindrical test specimens, a multi-piece, split-collet arrangement acts as the grip interface at button-headfillets of the test specimen (3) as illustrated

41、in Fig. 4. Becauseof the limited contact area at the test specimen/grip interface,soft, deformable collet materials may be used to conform to theexact geometry of the test specimen. In some cases, taperedcollets may be used to transfer the axial force into the shank ofthe test specimen rather than i

42、nto the button-head radius (3).Moderately close tolerances are required for concentricity ofboth the grip and test specimen diameters. In addition, toler-ances on the collet height must be maintained to promoteuniform axial loading at the test specimen/grip interface.Tolerances will vary depending o

43、n the exact configuration asshown in the appropriate test specimen drawings.6.2.3.2 For flat test specimens, pins or pivots act as gripinterfaces at either the shoulders of the test specimen shank orat holes in the gripped test specimen head (4-6). Closetolerances are required of shoulder radii and

44、grip interfaces topromote uniform contact along the entire test specimen/gripinterface, as well as to provide for non-eccentric loading asshown in Fig. 5. Moderately close tolerances are required forlongitudinal coincidence of the pin and hole centerlines asillustrated in Fig. 6.6.3 Load Train Coupl

45、ers:6.3.1 GeneralVarious types of devices (load train cou-plers) may be used to attach the active or passive grip interfaceassemblies to the testing machine. The load train couplers, inconjunction with the type of gripping device, play major rolesin the alignment of the load train and thus subsequen

46、t bendingimposed in the test specimen. Load train couplers can beclassified as fixed and nonfixed as discussed in the followingsections. Note that use of well-aligned fixed or self-aligningnonfixed couplers does not automatically guarantee low bend-ing in the gage section of the tensile test specime

47、n. Well-aligned fixed or self-aligning nonfixed couplers provide forwell aligned load trains, but the type and operation of gripinterfaces, as well as the as-fabricated dimensions of the tensiletest specimen, can add significantly to the final bendingimposed in the gage section of the test specimen.

48、6.3.1.1 Regardless of which type of coupler is used, align-ment of the testing system must be verified at a minimum at thebeginning and end of a test series.An additional verification ofalignment is recommended, although not required, at themiddle of the test series. Either a dummy or actual testspe

49、cimen and the alignment verification procedures detailed inthe appendixes must be used. Allowable bending requirementsare discussed in 6.4. Tensile test specimens used for alignmentverification should be equipped with a recommended eightseparate longitudinal strain gages to determine bending contri-butions from both eccentric and angular misalignment of thegrip heads. (Although it is possible to use a minimum of sixseparate longitudinal strain gages for test specimens withcircular cross sections, eight strain gages are recommendedhere for simplicity and c