气体保护药芯焊丝焊接工艺性能的研究

南京航空航天大学硕士学位论文碱性渣系混合气体保护药芯焊丝焊接工艺性能的研究姓名：张平申请学位级别：硕士专业：材料加工工程指导教师：刘仁培20080301IMgO--SiO2-TiO2MgO25%12%LookoutWeldoffice2000MgO22%CaF26%Na2SiF69%MgO22%~25%SiO25%~7%15%TiO213%~15%MgO(22%~25%)-CaF2+Na2SiF6(15%)-SiO2(5%~7%)-TiO2(15%):IIABSTRACTFluxcoredwiresarethemostattractivenewweldingmaterialswiththefastestdevelopingspeedinrecentyears.Inordertoimprovetheweldingoperationperformanceofbasicfluxcoredwire,thepaperhasmodifiedthepresentslagsystemanddevelopedanewslagsystemformixturegas-shieldedfluxcoredwire,i.e.MgO-fluoride-SiO2-TiO2slagsystem.Thepaperhascarriedonsystematicresearchanddiscussionaroundslagsystemcompositioninfluencesondroplettransferformations,weldingarcstability,slagcoveringabilityanddetachabilityofthefluxcoredwire.Theeffectsofslagsystemcompositionondroplettransferformationsoffluxcoredwireandweldingspatterwereinvestigatedbyhigh-speedphotography,bycollectingdropletsinawaterthroughandtestofspatter.TheresultsshowedthatwhenMgOwaslessthan25%,thedroplettransferwassteadywithrelativelysmallmoltendropletsandweldingspatterwassmallertoo.ReplacingapartofCaF2withNa2SiF6couldreduceweldingspatterwiththinningmoltendrops.ButwhentheNa2SiF6wasmorethan12%,itwouldincreasetheweldingspatter.ThearcvoltageandweldingcurrentwasrecordedsynchronouswiththesoftwareLookoutWeldoffice2000whichmatchedwiththeweldingmachine,andthenthearcvoltageandweldingelectriccurrentoscillogramwereproducedaccordingthesedata.Atthesametime,theelectricarcshapecouldbeobservedthroughthehigh-speedphotography.Theeffectsofslagsystemcompositiononweldingarcstabilityofthefluxcoredwirewerethereforestudied.TheresultsshowedthatwhenMgOwasabout22%,CaF2was6%andNa2SiF6was9%,theweldingarcstabilitywaswell.Thepaperhasinvestigatedtheslagsystemcompositioninfluencesonslagcoveringabilityandslagdetachabilitybyslagcoveringabilityevaluatingandslagdetachabilitytesting,andestablishedslagdetachabilitymathematicalmodel.TheresultsshowedthatwhenthecontentsofMgOwas22%~25%,SiO2was5%~7%,fluoridewasabout15%andTiO2was13%~15%,theslagwascoveredwellanditwaseasytotakeoff.Inaddition,thepaperhasanalyzedthemicrostructuresofslag,theinnersurfacestructureofslagandthecharacteristicofslagfracture.TheresultsshowedthatitwasbenefitfortheslagdetachabilitywhenthemicrostructureofslagIIIwascoarse,thesecondphaseofmicrostructurepresentedstrip-shapeddistribution,andtheslagstructurewascompact,and,contrariwise,theslagdetachabilitybecameworse.Finally,thepaperhasacquiredtheslagsystemcompositionforthefluxcoredwirewithfavorableweldingoperationperformance,i.e.MgOwas22%~25%,CaF2andNa2SiF6were15%,SiO2was5%~7%andTiO2wasabout15%.Keywords:Fluxcoredwire,Weldingoperationperformance,Droplettransfer,Arcstability,SlagdetachabilityVI1.1.....................................................................................21.2.................................................................................................21.3.....................................................................42.1...........................................................................172.2...................................................................................182.3Fronius.........................................................................................182.4...................................................................................182.5...............................................................................192.6...................................................................................202.7...................................................................................212.8.......................................................222.9.......................................................................................222.10.............................................................................233.1MgO.........................................................................253.2MgO.................................................................................253.3MgO.........................................................................263.4MgO......................................................................................273.5...................................................................................293.6....................................................313.7...........................................................................................323.8...........................................................................332.1...........................................................................................162.2...............................................................................................183.1MgO..........................................................................243.2...........................................................................................263.3CaF2...........................................................................283.4...........................................................................303.5......................