简介：ThefatiguebehaviorofweldedstructuresiscurrentlydeterminedbymeansofrecommendationsdefinedintermsofS-Ncurvecorrespondingtothedetailclassesofweldedjointswithouttakingaccountoftheactualgeometryoftheweld.AnewfatiguestrengthassessmentmethodbasedonDangVanmultiaxialfatiguelimitcriterionwasintroduced,whichisnamedthelocalapproachandpresentedbyInstitutdeSoudurerecently.Thelocalapproachhasadvantagesintakingweldingresidualstressesandthegeometryoftheweldtoeandweldrootintoconsideration.TheapplicationofthelocalapproachtothefatiguestrengthassessmentoflowcarbonsteelQ235Bweldedjointswasstudied.ThefatiguetestsandfiniteelementanalysisresultsshowthatthelocalapproachparametersrecommendedbyInstitutdeSoudurewereincorrectlyforlowcarbonsteelQ235Bweldedjoints.Withaluminumalloyweldedjointsbeingusedwidely,theparametersofthelocalapproachusedforaluminumalloyweldedjointswereobtainedandverifiedonbasesofthefatiguetestsandfiniteelementanalysis.

简介：Inthisinvestigation,themechanicalpropertiesandlow-temperaturefracturetoughnessofAPI5LX65offshorepipelineweldedjointswerestudied.StructureIntegrityAssessmentProcedure(SINTAP)-FailureAssessmentDiagram(FAD)methodwasappliedtothepipestructurewithsurfaceflawattheweldtoe.AccordingtotheISOstandardBS7448,theCTODfracturetoughnessoftheweldedjointswasdeterminedatthetemperatureof0℃.Fortheheat-affectedzone(HAZ)specimens,post-testmetallographicanalysiswasperformedtoverifythatthetipofthecrackwaslocatedinthecoarsecrystalzoneinordertoconfirmthevalidityoftheaboveresults.Thefailurelinesofanalysislevel1and3ofweldmetalwerederivedfromtheresultsofthemechanicalpropertytest.Theassessmentwasperformed,consideringthemaximumlaystress,residualstressconservativelyassumedtobeuniformtensilestress,andminimumCTODvalue.Theresultsoftheassessmentshowedthatpipelinestructurewithasurfaceflaw(theheightandlengtharerespectively2.2mmand5mm)attheweldtoeissafe.ThisstudylaysthefoundationofapplicationofSINTAPtopipelinestructureassessment.