6061-T6铝合金疲劳曲线

FATIGUEDESIGNCURVESFOR6061-T6ALUMINUM*G.T.YahrEngineeringTechnologyDivisionOakRidgeNationalLaboratoryOakRidge,Tennessee37831-8051ABSTRACTArequesthasbeenmadetotheASMEBoilerandPressureVesselCommitteethat6061-T6aluminumbeapprovedforuseintheconstructionofClass1weldednuclearvesselssoitcanbeusedforthepressurevesseloftheAdvancedNeutronSourceresearchreactor.Fatiguedesigncurveswithandwithoutmeanstresseffectshavebeenproposed.Aknock-downfactoroftwoisappliedtothedesigncurveforevaluationofwelds.Thebasisofthecurvesisexplained.Thefatiguedesigncurvesarecomparedtofatiguedatafrombasemetalandweldments.DISCLAIMERThisreportwaspreparedasanaccountofworksponsoredbyanagencyoftheUnitedStatesGovernment.NeithertheUnitedStatesGovernmentnoranyagencythereof,noranyoftheiremployees,makesanywarranty,expressorimplied,orassumesanylegalliabilityorresponsi-bilityfortheaccuracy,completeness,orusefulnessofanyinformation,apparatus,product,orprocessdisclosed,orrepresentsthatitsusewouldnotinfringeprivatelyownedrights.Refer-encehereintoanyspecificcommercialproduct,process,orservicebytradename,trademark,manufacturer,orotherwisedoesnotnecessarilyconstituteorimplyitsendorsement,recom-mendation,orfavoringbytheUnitedStatesGovernmentoranyagencythereof.TheviewsandopinionsofauthorsexpressedhereindonotnecessarilystateorreflectthoseoftheUnitedStatesGovernmentoranyagencythereof.IPreparedbytheOAKRIDGENATIONALLABORATORY,OakRidge,Tennessee37831;managedbyMARTINMARIETTAENERGYSYSTEMS,INC.,fortheU.S.DEPARTMENTOFENERGYundersukninedmnuscrgthasauthoredbyatontractoroftheU.S.GW4mWltunderContractNo.DE-~~05-840~21400.~ccot~.theU.S.GovernmentrstahrramXdupive.royslty-heeEanw,topa~shthepasjhedfmofttnmnibutan.QContractNo.DE-AC05-MOR*W0th~fOdoSo.forUS.GovernmentPUJP=%.-*OlSTRlBUTiONOFTHISDOCUMENTISUNLIMITm--#**,*....4.........*.-....-.y----DISCLAIMERPortionsofthisdocumentmaybeillegibleinelectronicimageproducts.Imagesareproducedfromthebestavailableoriginaldocument.a2NOMENCLATUREA=constantinEq.1B=constantinEq.1E=elasticmodulusN=fatiguelifeR=ratioofminimumstresstomaximumstressinafatiguetestRA=percentreductionofareaS=strainamplitudetimeselasticmodulusSa=allowableamplitudeofalternatingstressintensitySe=endurancelimitSf=fatiguestrengthunderfullyreversedloadingSf'=fatiguestrengthinpresenceofmeanstressSm=meanstressSu=tensilestrengthS,=cyclicyieldstrength31.INTRODUCI’IONOakRidgeNationalLaboratory(ORNL)hasproposedanewfacilityforneutronresearch,centeredaroundanewresearchreactor,calledtheAdvancedNeutronSource(ANS)(West,1988;Harrington,1991).Thereactorwillrequireextensiveuseof6061-T6aluminumintheprimarypressureboundary.TheANSistobeauserexperimentalfacilityformanyscientificfields,includingneutronscatteringwithcold,thermal,andhotneutrons(themostimportantscientificjustificationfortheproject);engineeringmaterialsirradiation;isotopeproduction(includingtransuraniumisotopes);materialsanalysis;andnuclearscience.ItisanticipatedthattheANSwillleadtoimportanttechnologicaldevelopmentsthatwillenhanceourglobalcompetitiveness.Theuserrequirements,particularlytheneedforalarge,accessiblevolumeofaveryhighthermalneutronflux,determinethemainfeatures{highpower[-300MW(t)]andsmallsize}ofthereactorcoredesign.Thebasicconceptisconventional:aheavy-water-cooledandreflectedreactor.Thecoolantinlettemperatureisexpectedtobe45OC(113OF)andthebulkcoolantoutlettemperatureisexpectedtobe85OC(185°F).Theinletpressurewillbe3.5MPa(508psi).Theprimarypressureboundaryisalong0.5m(20in.)diameter6061-T6aluminumvesselwithflangesonbothendssothatitcanbeperiodicallyreplacedasrequiredduetoembrittlementcausedbyneutronirradiation.Outsidetheprimarypressureboundaryvessel,therewillalsobea3.5m(11.5ft)diameter6061-T6aluminumreflectortankwithnumerouspenetrationsandattachmentsthatwillcontainheavywateratapressureofabout0.5Wa(75psig).Theheavywaterinthereflectortankwillbeatatemperaturebelow46°C(115OF).Aluminumhasbeenemployedasastructuralmaterialinmostresearchreactors.Thealuminumalloy6061-T6hasbeensuccessfullyusedinstructuralapplicationsinseveralresearchreactorsincludingtheHighFluxIsotopeReactor(HFIR)atOakRidgeandtheHighFluxBeamReactor(HFBR)atBrookhavenNationalLaboratory.TheHFBRreactorvesselis6061-T6aluminum.ItwasdesignedinaccordancewiththeASMEBoilerandPressureVesselCodeforUnfiredPressureVessels,SectionVIII(1959),includingallrevisions,addenda,andapplicablecodecaserulingsineffectatthedateofawardoftheconstructioncontract.Inaddition,criticalareasofthevesselwherediscontinuitystressescouldbeappreciablewereexaminedandanalyzedinaccordancewiththedocument“TentativeStructuralDesignBasisforReactorPressureVesselsandDirectlyAssociatedComponents”(1958)alongwithformulaefromreports,documentsandpublicationsbyBijlaard,Horvay,Galletly,etal.4PreviousDepartmentofEnergy(DOE)researchreactorshavenotbeenrequiredtobebuiltaccordingtotheASMENuclearCode.However,DOEOrder5480.4EnvironmentalProtection,Safety,andHealthProtectionStandards(1984)specificallyrequiresallDOEandDOEcontractoroperationstoapplytheASMEBoilerandPressureVesselCodetoDOE-ownedreactors.Therefore,itwillbenecessarythatthemate