【astm標(biāo)準(zhǔn)】e 2714 - 13

1、Designation:E2714?13StardTestMethodfCreepFatigueTesting1ThisstardisissuedunderthefixeddesignationE2714thenumberimmediatelyfollowingthedesignationindicatestheyearofiginaladoptioninthecaseofrevisiontheyearoflastrevision.An

2、umberinparenthesesindicatestheyearoflastreapproval.Asuperepsilon()indicatesaneditialchangesincethelastrevisionreapproval.1.Scope1.1Thistestmethodcoversthedeterminationofmechanicalpropertiespertainingtocreepfatiguedefmati

3、oncrackfmationinnominallyhomogeneousmaterialsbothbytheuseoftestspecimenssubjectedtouniaxialfcesunderisothermalconditions.Itconcernsfatiguetestingatstrainrateswithcyclesinvolvingsufficientlylongholdtimestoberesponsiblefth

4、ecyclicdefmationresponsecyclestocrackfmationtobeaffectedbycreep(oxidation).Itisintendedasatestmethodffatiguetestingperfmedinsupptofsuchactivitiesasmaterialsresearchdevelopmentmechanicaldesignprocessqualitycontrolproductp

5、erfmancefailureanalysis.Thecyclicconditionsresponsiblefcreepfatiguedefmationcrackingvarywithmaterialwithtemperaturefagivenmaterial.1.2Theuseofthistestmethodislimitedtospecimensdoesnotcovertestingoffullscalecomponentsstru

6、cturesconsumerproducts.1.3Thistestmethodisprimarilyaimedatprovidingthematerialpropertiesrequiredfassessmentofdefectfreeengineeringstructurescontainingfeaturesthataresubjecttocyclicloadingattemperaturesthataresufficiently

7、hightocausecreepdefmation.1.4Thistestmethodisapplicabletothedeterminationofdefmationcrackfmationnucleationpropertiesasaconsequenceofeitherconstantamplitudestraincontrolledtestsconstantamplitudefcecontrolledtests.Itisprim

8、arilyconcernedwiththetestingofroundbartestspecimenssubjectedtouniaxialloadingineitherfcestraincontrol.Thefocusoftheprocedureisontestsinwhichcreepfatiguedefmationdamageisgeneratedsimultaneouslywithinagivencycle.Itdoesnotc

9、overblockcycletestinginwhichcreepfatiguedamageisgeneratedsequentially.Datathatmaybedeterminedfromcreepfatiguetestsperfmedunderconditionsinwhichcreepfatiguedefmationdamageisgeneratedsimultaneouslyinclude(a)cyclicstressstr

10、aindefmationresponse(b)cycliccreep(relaxation)defmationresponse(c)cyclichardeningcyclicsofteningresponse(d)cyclestofmationofasinglecrackmultiplecracksintestspecimens.NOTE1—Acrackisbelievedtohavefmedwhenithasnucleatedprop

11、agatedinaspecimenthatwasinitiallyuncrackedtoaspecificsizethatisdetectablebyastatedtechnique.Fthepurposeofthisstardthefmationofacrackisevidencedbyameasurableincreaseincomplianceofthespecimenbyasizedetectablebypotentialtec

12、hnique.Specificdetailsofhowtomeasurecyclestocrackfmationaredescribedin9.5.1.1.5Thistestmethodisapplicabletotemperaturesstrainratesfwhichthemagnitudesoftimedependentinelasticstrains(creep)areonthesamederlargerthantimeinde

13、pendentinelasticstrain.NOTE2—Theterminelasticisusedhereintorefertoallnonelasticstrains.Thetermplasticisusedhereintoreferonlytotimeindependent(thatisnoncreep)componentofinelasticstrain.Ausefulengineeringestimateoftimeinde

14、pendentstraincanbeobtainedwhenthestrainrateexceedssomevalue.Fexampleastrainrateof1103sec1isoftenusedfthispurpose.Thisvalueshouldincreasewithincreasingtesttemperature.1.6ThevaluesstatedinSIunitsaretoberegardedasstard.Noot

15、herunitsofmeasurementareincludedinthisstard.1.7Thisstarddoesnotpurpttoaddressallofthesafetyconcernsifanyassociatedwithitsuse.Itistheresponsibilityoftheuserofthisstardtoestablishappropriatesafetyhealthpracticesdetermineth

16、eapplicabilityofregulatylimitationspritouse.2.ReferencedDocuments2.1ASTMStards:2E4PracticesfFceVerificationofTestingMachinesE8E8MTestMethodsfTensionTestingofMetallicMaterialsE83PracticefVerificationClassificationofExtens

17、ometerSystemsE111TestMethodfYoung’sModulusTangentModulus1ThistestmethodisunderthejurisdictionofASTMCommitteeE08onFatigueFractureisthedirectresponsibilityofSubcommitteeE08.05onCyclicDefmationFatigueCrackFmation.Currentedi

18、tionapprovedJune152013.PublishedJuly2013.iginallyapprovedin2009.Lastpreviouseditionapprovedin2009asE2714–09ε1.DOI:10.1520E2714–13.2FreferencedASTMstardsvisittheASTMwebsitewww.astm.gcontactASTMCustomerServiceat.FAnnualBoo

19、kofASTMStardsvolumeinfmationrefertothestard’sDocumentSummarypageontheASTMwebsite.Copyright?ASTMInternational100BarrHarbDrivePOBoxC700WestConshohockenPA194282959.UnitedStates13.3Definitions:3.3.1cycle—Infatigueonecomplete

20、sequenceofvaluesoffce(strain)thatisrepeatedunderconstantamplitudeloading(straining)3.3.2holdtimeτh[T]—Infatiguetestingtheamountoftimeinthecyclewherethecontrolledtestvariable(fcestraindisplacement)remainsconstantwithtime(

21、Fig.3).3.3.2.1Discussion—Holdtime(s)aretypicallyplacedatpeakstressstrainintensioncompressionbutcanalsobeplacedatotherpositionswithinthecycle.3.3.3totalcycleperiodτt[T]—Thetimefcompletionofonecycle.Theparameterτtcanbesepa

22、ratedintohold(τh)nonhold(τnh)(thatissteadydynamic)componentswherethetotalcycletimeisthesumoftheholdtimethenonholdtime.3.3.4hysteresisdiagram—Thestressstrainpathduringonecycle(seeFig.2).3.3.5initialmodulusofelasticityEo[F

23、L2]—Themodulusofelasticitydeterminedduringtheloadingptionofthefirstcycle.3.3.6modulusofelasticityatcycleN(EN[FL2]—Theaverageofthemodulusofelasticitydeterminedduringincreasingloadption(seeEcinFig.2)thedecreasingloadption(

24、ETinFig.2)ofthehysteresisdiagramftheNthcycle.3.3.7stressrange?σ[FL2]—Thedifferencebetweenthemaximumminimumstresses.3.3.7.1Discussion—Fcreepfatigueteststhedifferencebetweenthemaximumminimumstressesiscalledthe“peakstressra

25、nge”ftestsconductedunderstraincontrolthedifferencebetweenthestressesatthepointsofreversalofthecontrolparameteriscalledthe“relaxedstressrange”(seeFig.2b).3.4DefinitionsofTermsSpecifictoThisStard:3.4.1DCPDACPD—Directcurren

26、talternatingcurrentelectricalpotentialcrackmonitinginstrumentation.3.4.2homologoustemperature—ThespecimentemperatureinKdividedbythemeltingpointofthematerialalsoinK.3.4.3crackfmation—Acrackisbelievedtohavefmedwhenithasnuc

27、leatedpropagatedinaspecimenthatwasinitiallyuncrackedtoasizethatisdetectablebyastatedtechnique.4.SignificanceUse4.1Creepfatiguetestingistypicallyperfmedatelevatedtemperaturesinvolvesthesequentialsimultaneousapplicationoft

28、heloadingconditionsnecessarytogeneratecyclicdefmationdamageenhancedbycreepdefmationdamageviceversa.Unlesssuchtestsareperfmedinvacuumaninertenvironmentoxidationcanalsoberesponsiblefimptantinteractioneffectsrelatingtodamag