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1、co2气保焊气孔分析AnalysisofthecausesofporosityinC02gasshieldedweldingstomaC02electricarcwelding,thewe1dpoolsurfacewithoutslagcover,C02airandstrongcoolingeffect,thusthemoltenmetalsolidificationisfaster,butthegastoolatetoescape,itiseasytoproduceintheporesintheweld.Thereare3possibletypesofpores:carbonmonox
2、idepore,hydrogenporeandnitrogenpore.Onereason,carbonmonoxideporesCOstoma,mainlyinthepoolofFeOandCreductionreactionoccursasfollows:FeO+C二二Fe+CO,thereactioninthecrystallizationtemperatureofthemoltenpool,wasrelativelyintense,becausewhenthemoltenpoolhasbeensolidified,COgasisnoteasytoescape,sotheforma
3、tionofporesintheweldinCO.IftheweldingwirecontainsenoughdeoxidizingelementsSiandMn,andthecarboncontentintheweldingwireislimited,thereductionreactioncanbesuppressed,andthegenerationofCOporositycanbeeffectivelyprevented.Therefore,inC02arcwelding,aslongastheweldingwireischosenproperly,thepossibilityo
4、fproducingCOporosityisverysmal1.Two.HydrogenholeIfthemoltenpoolisdissolvedintoalargeamountofhydrogenathightemperature,itwillnotbedischargedsufficientlyduringthecrystallizationprocess,andthentheporositywillremainintheweldmetaLThehydrogeninthearczonemainlycomesfromtheweldingwire,theoilstainandrusto
5、nthesurfaceoftheworkpiece,andthemoisturecontainedintheC02gas・0订ishydrocarbons,andrustcontainscrystallinewater,whichdecomposeshydrogenathightemperatures・ToreducethedissolvedamountofH2inpool,notonlycanpreventhydrogenporosity,butalsoimprovetheductilityoftheweldmeta1.Therefore,ontheonehand,beforeweld
6、ingtoproperlyremovetheworkpieceandweldingwiresurfaceoilandrust,ontheotherhandshouldbeusedaslowaspossiblewithlowmoistureC02gas・MoistureinC02gasisoftenthemaincauseofhydrogenhole・Inaddition,hydrogenisdissolvedinthemoltenpoolinionicform.WhentheDCpolarityisreversed,themoltenpoolisnegative・Itemitsalarg
7、eamountofelectrons,andthehydrogeniononthesurfaceofthebathpooliscompoundedintoatoms,thusreducingtheamountofhydrogenionsenteringthemoltenpool.Therefore,whentheDCpolarityisreversed,thehydrogencontentintheweldis1/3to1/5whe
