ASTM E1820-05a Standard Test Method for Measuremen

Designation:E1820–05aStandardTestMethodforMeasurementofFractureToughness1ThisstandardisissuedunderthefixeddesignationE1820;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(e)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope1.1Thistestmethodcoversproceduresandguidelinesforthedeterminationoffracturetoughnessofmetallicmaterialsusingthefollowingparameters:K,J,andCTOD(d).Tough-nesscanbemeasuredintheR-curveformatorasapointvalue.Thefracturetoughnessdeterminedinaccordancewiththistestmethodisfortheopeningmode(ModeI)ofloading.1.2Therecommendedspecimensaresingle-edgebend,[SE(B)],compact,[C(T)],anddisk-shapedcompact,[DC(T)].Allspecimenscontainnotchesthataresharpenedwithfatiguecracks.1.2.1Specimendimensional(size)requirementsvaryac-cordingtothefracturetoughnessanalysisapplied.Theguide-linesareestablishedthroughconsiderationofmaterialtough-ness,materialflowstrength,andtheindividualqualificationrequirementsofthetoughnessvaluepervaluessought.1.3ThevaluesstatedinSIunitsaretoberegardedasthestandard.Thevaluesgiveninparenthesesareforinformationonly.1.4Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappro-priatesafetyandhealthpracticesanddeterminetheapplica-bilityofregulatorylimitationspriortouse.NOTE1—OtherstandardmethodsforthedeterminationoffracturetoughnessusingtheparametersK,J,andCTODarecontainedinTestMethodsE399,E813,E1152,E1290,andE1737.Thistestmethodwasdevelopedtoprovideacommonmethodfordeterminingallapplicabletoughnessparametersfromasingletest.2.ReferencedDocuments2.1ASTMStandards:2E4PracticesforForceVerificationofTestingMachinesE8TestMethodsforTensionTestingofMetallicMaterialsE21TestMethodsforElevatedTemperatureTensionTestsofMetallicMaterialsE399TestMethodforLinear-ElasticPlane-StrainFractureToughnessKIcofMetallicMaterialsE1290TestMethodforCrack-TipOpeningDisplacement(CTOD)FractureToughnessMeasurementE1823TerminologyRelatingtoFatigueandFractureTest-ingE1921TestMethodforDeterminationofReferenceTem-perature,To,forFerriticSteelsintheTransitionRangeE1942GuideforEvaluatingDataAcquisitionSystemsUsedinCyclicFatigueandFractureMechanicsTesting3.Terminology3.1TerminologyE1823isapplicabletothistestmethod.3.2Definitions:3.2.1compliance[LF−1],n—theratioofdisplacementin-crementtoforceincrement.3.2.2crackdisplacement[L],n—theseparationvectorbe-tweentwopoints(onthesurfacesofadeformedcrack)thatwerecoincidentonthesurfacesofanidealcrackintheundeformedcondition.3.2.2.1Discussion—Inthispractice,displacement,v,isthetotaldisplacementmeasuredbyclipgagesorotherdevicesspanningthecrackfaces.3.2.3crackextension,Da[L],n—anincreaseincracksize.3.2.4crack-extensionforce,G[FL−1orFLL−2],n—theelasticenergyperunitofnewseparationareathatismadeavailableatthefrontofanidealcrackinanelasticsolidduringavirtualincrementofforwardcrackextension.3.2.5cracksize,a[L],n—alinealmeasureofaprincipalplanardimensionofacrack.Thismeasureiscommonlyusedinthecalculationofquantitiesdescriptiveofthestressanddisplacementfields,andisoftenalsotermedcracklengthordepth.3.2.5.1Discussion—Inpractice,thevalueofaisobtainedfromproceduresformeasurementofphysicalcracksize,ap,originalcracksize,ao,andeffectivecracksize,ae,asappro-priatetothesituationbeingconsidered.3.2.6crack-tipopeningdisplacement(CTOD),d[L],n—thecrackdisplacementduetoelasticandplasticdeforma-tionatvariouslydefinedlocationsneartheoriginalcracktip.1ThistestmethodisunderthejurisdictionofASTMCommitteeE08onFatigueandFractureandisthedirectresponsibilityofSubcommitteeE08.08onElastic-PlasticFractureMechanicsTechnology.CurrenteditionapprovedDec.1,2005.PublishedJanuary2006.Originallyapprovedin1996.Lastpreviouseditionapprovedin2005asE1820–05.2ForreferencedASTMstandards,visittheASTMwebsite,@astm.org.ForAnnualBookofASTMStandardsvolumeinformation,refertothestandard’sDocumentSummarypageontheASTMwebsite.1Copyright©ASTMInternational,100BarrHarborDrive,POBoxC700,WestConshohocken,PA19428-2959,UnitedStates.—Inthistestmethod,CTODisthedis-placementofthecracksurfacesnormaltotheoriginal(un-loaded)crackplaneatthetipofthefatigueprecrack,ao.Inthistestmethod,CTODiscalculatedattheoriginalcracklength,ao,frommeasurementsmadefromtheforceversusdisplace-mentrecord.3.2.6.2Discussion—InCTODtesting,dIc[L]isavalueofCTODneartheonsetofslowstablecrackextension,heredefinedasoccurringatDap=0.2mm(0.008in.)+0.7dIc.3.2.6.3Discussion—InCTODtesting,dc[L]isthevalueofCTODattheonsetofunstablecrackextension(see3.2.28)orpop-in(see3.2.17)whenDap0.2mm(0.008in.)+0.7dc.ThedccorrespondstotheforcePcandclip-gagedisplacementvc(seeFig.1).Itmaybesize-dependentandafunctionoftestspecimengeometry.3.2.6.4Discussion—InCTODtesting,du[L]isthevalueofCTODattheonsetofunstablecrackextension(see3.2.28)orpop-in(see3.2.17)whentheeventisprecededbyDap0.2mm(0.008in.)+0.7du.Theduc