焊缝RT底片的评判规律及典型缺陷图谱.docx

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