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.
简介:Whenmeasuringresidualstressofcoarse-grainaluminumalloyusingX-raydiffractionmethod,thediffractionprofileshowstwopeaksandpositionofmeasured2dwillbechanged,whichleadtoaninaccuratemeasurementresult.Hence,inthispaper,somemethodswereemployedtoimprovethemeasurementaccuracy.Duringthemeasuringprocess,differentparameters(diameterofirradiatedarea,Ψ-oscillationrangeandexposuretime)wereselectedandprofilepeakshiftmethodwasutilized.Moreover,whenthe20ofprofileswasdetermined,differentcalculationmethodswereusedtocalculatetheresidualstress.TheresultsshowthatdiameterofirradiatedareaandΨ-oscillationrangehavesignificantinfluenceonthemeasuringresult.Forstressvaluecalculateddirectlyfromthetestequipment,crosscorrelationmethodismoreaccuratethantheabsolutepeak.Furthermore,anothertwocalculationmethodsofslopewith2θ-sin~2Ψande-sin~2Ψwereusedtocalculatethestressbasedonparameters(2θ,ε)obtainedfromcrosscorrelationmethod.Itisconcludedthat20-sin~2Ψmethodcanfurtherimprovethemeasurementaccuracy.
简介:"GasTransmittingFromWesttoEastProject"issignificant.Itshouldensuretheweldingqualityandsafetyofpipeline.Thetaskisveryarduoustoguaranteethequalityoftheprojectintheconditionoflongline,complexweatherandgeologyfeatures.Inthispaper,theweldingcoldcrackingsusceptibilityofdomesticX-70pipelinesteeladoptedbytheproject,whichisoneofthemostinterestingquestionsofweldingqualityaboutpetrolpipeline,wasstudiedbymeansofobliqueY-groovecrackingtest.Thecrackratioofsurfaceandsectionwastestedundertheconditionsofdifferentweldingmaterialsandpreheattemperature.TheX-70pipelinesteelhasgoodcrackresistance.Theresearchhasimportantvaluefortheconstructionoflarge-scalepipelineengineeringandtheapplicationofdomesticX-70pipelinesteel.
简介:ThesusceptibilityofweldedjointfortheX65pipelinesteeltoH2Sstresscorrosioncracking(SCC)isinvestigated.SCCtestsonthesteelarecarriedoutintheenvironmentbasedonNACETM-01-77solutionwithsaturatedgaseousH2S.Thethresholdstressintensityfactorandcrackpropagationvelocityarecalculatedaccordingtowedge-openingloading(WOL)specimens.Thethree-dimensionalelastic-plasticfiniteelementanalysisofWOLspecimensisperformedbyusingtheFEMprogrammingpackageANSYS.Stressfieldandconcentrationofhydrogendistributionpropertyaheadofthecracktipareobtained.ThispapersurveyedthemicrostructureofweldedjointandstudiedonthemechanicalpropertiesofX65pipelinesteel.Itprovidesexperimentalbasisforstudyingstresscorrosion.Theresultsofnumericalanalysisareconsistentwithconclusionsofstresscorrosiontest.
简介:随着焊接技术的进步,不断涌现的新型材料在焊接结构中的大量采用,焊机和焊接工艺面临着更高的要求。有些问题仅仅靠一种焊接工艺难以解决,而需要手工电弧焊、脉冲氩弧焊、脉冲熔化极气体保护焊等多种焊接方式的结合,也对焊机提出多功能要求。而逆变电源工作频率高,控制性能好,因此,逆变焊接电源是实现多功能焊接的一种理想选择。