焊缝RT底片的评判规律及典型缺陷图谱.docx
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焊缝RT底片的评判规律及典型缺陷图谱.docx
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焊缝RT底片的评判规律及典型缺陷图谱
焊缝射线照相底片的评判规律
一、探伤人员要评片,四项指标放在先*,底片标记齐又正,铅字压缝为废片。
二、评片开始第一件,先找四条熔合线,小口径管照椭圆,根部都在圈里面。
三、气孔形象最明显,中心浓黑边缘浅,夹渣属于非金属,杂乱无章有棱边。
四、咬边成线亦成点,似断似续常相见,这个缺陷最好定,位置就在熔合线。
五、未焊透是大缺陷,典型图象成直线,间隙太小钝边厚,投影部位靠中间。
六、内凹只在仰焊面,间隙太大是关键,内凹未透要分清,内凹透度成弧线。
七、未熔合它斜又扁,常规透照难发现,它的位置有规律,都在坡口与层间。
八、横裂纵裂都危险,横裂多数在表面,纵裂分布范围广,中间稍宽两端尖。
九、还有一种冷裂纹,热影响区常发现,冷裂具有延迟性,焊完两天再拍片。
十、有了裂纹很危险,斩草除根保安全,裂纹不论长和短,全部都是Ⅳ级片。
十一、未熔和也很危险,黑度有深亦有浅,一旦判定就是它,亦是全部Ⅳ级片。
十二、危害缺陷未焊透,Ⅱ级焊缝不能有,管线根据深和长,容器跟着条渣走**。
十三、夹渣评定莫着忙,分清圆形和条状,长宽相比3为界,大于3倍是条状。
十四、气孔危害并不大,标准对它很宽大,长径折点套厚度,中间厚度插入法。
十五、多种缺陷大会合,分门别类先评级,2类相加减去Ⅰ,3类相加减Ⅱ级。
十六、评片要想快又准,下拜焊工当先生,要问诀窍有哪些,焊接工艺和投影。
注:
*四项指标系底片的黑度、灵敏度、清晰度、灰雾度必须符合标准的要求。
**指单面焊的管线焊缝和双面焊的容器焊缝内未焊透的判定标准。
RadiographInterpretation-Welds
Inadditiontoproducinghighqualityradiographs,theradiographermustalsobeskilledinradiographicinterpretation.Interpretationofradiographstakesplaceinthreebasicstepswhichare
(1)detection,
(2)interpretation,and(3)evaluation.Allofthesestepsmakeuseoftheradiographer'svisualacuity.Visualacuityistheabilitytoresolveaspatialpatterninanimage.Theabilityofanindividualtodetectdiscontinuitiesinradiographyisalsoaffectedbythelightingconditionintheplaceofviewing,andtheexperiencelevelforrecognizingvariousfeaturesintheimage.Thefollowingmaterialwasdevelopedtohelpstudentsdevelopanunderstandingofthetypesofdefectsfoundinweldmentsandhowtheyappearinaradiograph.
Discontinuities
Discontinuitiesareinterruptionsinthetypicalstructureofamaterial.Theseinterruptionsmayoccurinthebasemetal,weldmaterialor"heataffected"zones.Discontinuities,whichdonotmeettherequirementsofthecodesorspecificationusedtoinvokeandcontrolaninspection,arereferredtoasdefects.
GeneralWeldingDiscontinuities
Thefollowingdiscontinuitiesaretypicalofalltypesofwelding.
Coldlapisaconditionwheretheweldfillermetaldoesnotproperlyfusewiththebasemetalorthepreviousweldpassmaterial(interpasscoldlap).Thearcdoesnotmeltthebasemetalsufficientlyandcausestheslightlymoltenpuddletoflowintobasematerialwithoutbonding.
Porosity气孔istheresultofgasentrapmentinthesolidifyingmetal.Porositycantakemanyshapesonaradiographbutoftenappearsasdarkroundorirregularspotsorspecksappearingsingularly,inclustersorrows.SometimesporosityiselongatedandmayhavetheappearanceofhavingatailThisistheresultofgasattemptingtoescapewhilethemetalisstillinaliquidstateandiscalledwormholeporosity.Allporosityisavoidinthematerialitwillhavearadiographicdensitymorethanthesurroundingarea.
.
Clusterporosity链状气孔iscausedwhenfluxcoatedelectrodesarecontaminatedwithmoisture.Themoistureturnsintogaseswhenheatedandbecomestrappedintheweldduringtheweldingprocess.Clusterporosityappearjustlikeregularporosityintheradiographbuttheindicationswillbegroupedclosetogether.
Slaginclusions夹渣arenonmetallicsolidmaterialentrappedinweldmetalorbetweenweldandbasemetal.Inaradiograph,dark,jaggedasymmetricalshapeswithintheweldoralongtheweldjointareasareindicativeofslaginclusions.
Incompletepenetration(IP)orlackofpenetration(LOP)未焊透occurswhentheweldmetalfailstopenetratethejoint.Itisoneofthemostobjectionablewelddiscontinuities.Lackofpenetrationallowsanaturalstressriserfromwhichacrackmaypropagate.Theappearanceonaradiographisadarkareawithwell-defined,straightedgesthatfollowsthelandorrootfacedownthecenteroftheweldment.
Incompletefusion未熔合isaconditionwheretheweldfillermetaldoesnotproperlyfusewiththebasemetal.Appearanceonradiograph:
usuallyappearsasadarklineorlinesorientedinthedirectionoftheweldseamalongtheweldpreparationorjoiningarea.
Internalconcavityorsuckback内凹或吸入isconditionwheretheweldmetalhascontractedasitcoolsandhasbeendrawnupintotherootoftheweld.Onaradiographitlookssimilartolackofpenetrationbutthelinehasirregularedgesanditisoftenquitewideinthecenteroftheweldimage.
Internalorrootundercut内部或根部咬边isanerosionofthebasemetalnexttotherootoftheweld.Intheradiographicimageitappearsasadarkirregularlineoffsetfromthecenterlineoftheweldment.UndercuttingisnotasstraightedgedasLOPbecauseitdoesnotfollowagroundedge.
Externalorcrownundercut外部或顶部咬边isanerosionofthebasemetalnexttothecrownoftheweld.Intheradiograph,itappearsasadarkirregularlinealongtheoutsideedgeoftheweldarea.
Offsetormismatch错边aretermsassociatedwithaconditionwheretwopiecesbeingweldedtogetherarenotproperlyaligned.Theradiographicimageisanoticeabledifferenceindensitybetweenthetwopieces.Thedifferenceindensityiscausedbythedifferenceinmaterialthickness.Thedark,straightlineiscausedbyfailureoftheweldmetaltofusewiththelandarea.
Inadequateweldreinforcement未填满isanareaofaweldwherethethicknessofweldmetaldepositedislessthanthethicknessofthebasematerial.Itisveryeasytodeterminebyradiographiftheweldhasinadequatereinforcement,becausetheimagedensityintheareaofsuspectedinadequacywillbemore(darker)thantheimagedensityofthesurroundingbasematerial.
Excessweldreinforcement增强余高isanareaofaweld,whichhasweldmetaladdedinexcessofthatspecifiedbyengineeringdrawingsandcodes.Theappearanceonaradiographisalocalized,lighterareaintheweld.Avisualinspectionwilleasilydetermineiftheweldreinforcementisinexcessofthatspecifiedbytheindividualcodeinvolvedintheinspection.
Cracking裂纹canbedetectedinaradiographonlythecrackispropagatinginadirectionthatproducedachangeinthicknessthatisparalleltothex-raybeam.Crackswillappearasjaggedandoftenveryfaintirregularlines.Crackscansometimesappearingas"tails"oninclusionsorporosity.
DiscontinuitiesinTIGwelds
ThefollowingdiscontinuitiesarepeculiartotheTIGweldingprocess.Thesediscontinuitiesoccurinmostmetalsweldedbytheprocessincludingaluminumandstainlesssteels.TheTIGmethodofweldingproducesacleanhomogeneousweldwhichwhenradiographediseasilyinterpreted.
Tungsteninclusions.夹钨Tungstenisabrittleandinherentlydensematerialusedintheelectrodeintungsteninertgaswelding.Ifimproperweldingproceduresareused,tungstenmaybeentrappedintheweld.Radiographically,tungstenismoredensethanaluminumorsteel;therefore,itshowsasalighterareawithadistinctoutlineontheradiograph.
Oxideinclusions夹氧化物areusuallyvisibleonthesurfaceofmaterialbeingwelded(especiallyaluminum).Oxideinclusionsarelessdensethanthesurroundingmaterialsand,therefore,appearasdarkirregularlyshapeddiscontinuitiesintheradiograph.
DiscontinuitiesinGasMetalArcWelds(GMAW)
ThefollowingdiscontinuitiesaremostcommonlyfoundinGMAWwelds.
Whiskersareshortlengthsofweldelectrodewire,visibleonthetoporbottomsurfaceoftheweldorcontainedwithintheweld.Onaradiographtheyappearaslight,"wirelike"indications.
Burnthrough(icicles)resultswhentoomuchheatcausesexcessiveweldmetaltopenetratetheweldzone.Lumpsofmetalsagthroughtheweldcreatingathickglobularconditiononthebackoftheweld.Onaradiograph,burnthroughappearsasdarkspotssurroundedbylightglobularareas.
welld-02(IncompleteRootFusion、根部未熔合)
welld-03(InsuffucientReinforcement、增强高)
welld-04(ExcessRootPenetration、根部焊瘤)
welld-05(ExternalUndercut、外部咬肉)
welld-06(InternalUndercut、内部咬肉)
welld-07(RootConcavity、根部凹陷)
welld-08(BurnThrough、烧穿)
welld-09(IsolatedSlagInclusion、单个的夹渣)
welld-10(WagonTrack-SlagLine、线状夹渣)
welld-11(InterrunFusion、内部未熔合)
welld-12(LackofSidewallFusion、内侧未熔合)
welld-13(Porosity、气孔)
welld-14(ClusterPorosity、链状气孔)
welld-15(HollowBead、夹珠)
welld-16(TransverseCrack、横向裂纹)
welld-17(CenterlineCrack、中心线裂纹)
welld-18(RootCrack、根部裂纹)
welld-19(TungstenInclusion)夹钨
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- 焊缝 RT 底片 评判 规律 典型 缺陷 图谱