二次热循环对管线钢在役焊接粗晶区显微组织的影响

1)2)1),3300632)(),257061X70.,,,,.M-A.M-A,,M-A.,.X70;;;TG14211;TG406Effectofsecondthermalcycleonthemicrostructureofthecoarsegrainheat2af2fectedzoneofin2serviceweldedpipelinesteelCHENYuhua1),WANGYong2)1)SchoolofMaterialsScienceandEngineering,NanchangHangkongUniversity,Nanchang330063,China2)CollegeofMechanicalandElectronicEngineering,ChinaUniversityofPetroleum,Dongying257061,ChinaABSTRACTWeldingthermalsimulation,metallographicanalysisandtransmissionelectronmicroscope(TEM)wereusedtostudythemetallurgicalmicrostructureandfinestructureofthecoarsegrainheat2affectedzone(CGHAZ)ofin2serviceweldingandthezonesthatsubjecttosecondthermalcycleatdifferentpeaktemperatures.TheresultsshowthatthemainmetallurgicalmicrostructuresoftheCGHAZofin2serviceweldingaregranularbainiteandlathbainite.Aftersecondthermalcycle,thetypesofmicrostructurehavenochange,buttheshapeandamountofeachkindofmicrostructureandthegrainsizeoforiginalaustenitearedifferentwhenthepeaktemperatureofsecondthermalcycleisdifferent.ObservingbyTEM,thefinestructuresofeachHAZareferritelathsandM2Acon2stituentsthatdistributeonorbetweenferritelaths.TheM2AconstituentsintheCGHAZofin2serviceweldingaremainstrip2shaped.Aftersecondthermalcycle,theM2AconstituentsintheintercriticallyreheatedCGHAZarerefinedandlowerbainitethathastypicalmidribmorphologyproducesinthezone.KEYWORDSX70pipelinesteel;in2servicewelding;secondthermalcycle;microstructure:2007-08-07:2007-10-13:(1979),,,,E2mail:[e-mail](),,,[1-3].,,[4].[5-9],.,.,,X7030920089JournalofUniversityofScienceandTechnologyBeijingVol.30No.9Sep.2008©1994-2010ChinaAcademicJournalElectronicPublishingHouse.Allrightsreserved.(),tP2/5800500.1X70()Table1MaincompositionofX70pipelinesteel%CSiMnSPCrMoVNiTiNb01051148012601003010120102011701046011501017010522Table2ParametersofweldingthermalsimulationTP1/TP2/tP1/8/stP2/8/st8/5(tP2/5)/st5/3/st3/1/s11300459312130060065(2)9313130080065931413001000635931513001200655931X70120mm11mm6mm,DM-100A.(),,NikonEPIPHOT300U,4%.014mm,(TEM),H-800.22111300,X70,,1.,.212X70600,800,100012001Fig.1Metallurgicalmicrostructureofthecoarsegrainheat2affectedzone,2.600,800,10001200.2,(2(a)),,,,,.(2(b)),,,,.(2(c)),,,.(2(d)),.30019:©1994-2010ChinaAcademicJournalElectronicPublishingHouse.Allrightsreserved.(a)600;(b)800;(c)1000;(d)1200Fig.2Metallurgicalmicrostructuresofthecoarsegrainheat2affectedzoneaftersecondthermalcycleofdifferentpeaktemperatures:(a)600;(b)800;(c)1000;(d)1200,X70,,,.213TEM,,M-A,3.3TEMFig.3TEMmorphologyoftheheat2affectedzone,,4.,5.M-A,M-A,,M-A,.M-A.4Fig.4Morphologyofdislocationonthebainiticferritelaths,,,(6Z-Z),,,400130©1994-2010ChinaAcademicJournalElectronicPublishingHouse.Allrightsreserved.[10].5M-ATEM.(a);(b)Fig.5TEMmorphologyofM2Aconstituents:(a)longstrip;(b)irregularmass6Fig.6Midribmorphologyofbainite3(1)X70.,,.(2)M-A.M-A,,M-A,.(3),.[1]BruceWA.Repairofin2servicepipelinesbywelding.PipesPipelinesInt,2001,46(9/10):5[2]ChenYH,WangY,DongLX,etal.Advanceonrepairofpressurizedoilandgaspipelinesbyin2serviceweldingtechnology.PressureVesselTechnol,2005,22(2):36(,,,..,2005,22(2):36)[3]OteguiJL,RivasA,ManfrediC,etal.Weldfailuresinsleevereinforcementsofpipelines.EngFailureAnal,2001(8):57[4]BruceWA.Industrystandardscatchupwithin2servicewelding.WeldJ,1999,79(11):43[5]BangIW,SonYP,OhKH,etal.Numericalsimulationofsleeverepairweldingofin2servicegaspipelines.WeldJ,2002,81(12):273[6]ChenYH,JinHC,DongLX,etal.Experimentalstudyonin2serviceweldingofrunningpipelines.JUnivPet,2004,28(6):72(,,,..,2004,28(6):72)[7]CisilinoAP,ChapettiMD,OteguiJL.Minimumthicknessforcircumferentialsleeverepairfilletweldsincorrodedgaspipelines.IntJPressureVesselsPiping,2002,(79):67[8]ChenHN,QianBN,ZhuSC,etal.Hydrogencrackinganditspreventionmethodonfieldweldingontooilandgasin2servicepipeline.TransChinaWeldInst,1998,19(1):29(,,,..,1998,19(1):29)[9]SabapathyPN,WahabMA,PainterMJ.Thepredictionofburn2throughduringin2serviceweldingofgaspipeline.IntJPressureVesselsPiping,2000,77(10):669[10]WeiCF,LuanDC.Studyonbainiticmidribmorphology.TransMaterHeatTreat,2001,22(3):14(,..,2001,22(3):14)50019:©1994-2010ChinaAcademicJournalElectronicPublishingHouse.Allrightsreserved.