ML17059B590

Rev 0 to Metallurgical Evaluation of Failed Shroud Tie Rod Lower Spring Contact Wedge Latches, for June 1997

ML17059B590
Person / Time
Site:	Nine Mile Point
Issue date:	06/30/1997
From:	DELWICHE D E, HORN R M, RODABAUGH J F NIAGARA MOHAWK POWER CORP.
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ML17059B591	List: ML17059B590 ML18040A263
References
GENE-B13-01739, GENE-B13-01739-44-R0, GENE-B13-1739, GENE-B13-1739-44-R, NUDOCS 9706200179
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GENEB13-01739-44Revision0June1997MetallurgicalEvaluationofFailedShroudTieRodLowerSpringContactWedgeLatchesNineMilePointUnit1,RF014D.E.Delwiche,ProgramManagerMetallurgicalEvaluationsPlantMaterialsTechnology//~~ygReviewedby:R..Horn,EngineeringFellowMaterialsTechnologyApprovedby:J.F.Rodabaugh,MissionManarInVesselRepairsReactorModificationServices970b200i79970bisPDRADQCK05000220PPDR

GENEB13-01739-44Revision0June1997REVISIONSTATUSSHEETRevisionDraftArovalD.E.DehvicheDate5/5/97DraftIssueDescritionDraftAD.E.Delwiche5/13/97DraftIssue,witheditorialChangesDraftBD.E.Delwiche6/6/97DraftIssue,withadditionofMetallurgicalEvaluationResultsfor90and166degreewedgelatches.Rev.0D.E.Delwiche6/10/97ResolutionofReviewCommentsandMinorEditorialChanes

GENEB13-01739-44Revision0June1997IMPORTANTNOTICEREGARDINGCONTENTSOFTHISREPORTPleasereadcarefullyTheonlyundertakingsoftheGeneralElectricCompany(GE)respectinginformationinthisdocumentarecontainedinthecontractbetweenNiagaraMohawkPowerCorporationandGE,asidentifiedinPO15247,andnothingcontainedinthisdocumentshallbeconstruedaschangingthecontract.TheuseofthisinformationbyanyoneotherthanNiagaraMohawkPowerCorporation,orforanypurposeotherthanthatforwhichitisintendedisnotauthorized;andwithrespecttoanyunauthorizeduse,GEmakesnorepresentationorwarranty,expressorimplied,andassumesnoliabilityastothecompleteness,accuracy,orusefulnessoftheinformationcontainedinthisdocument,orthatitsusemaynotinfringeuponprivatelyownedrights.

GENEB13-01739-44Revision0,June1997EXECUTIVESUMMARYDuringtheSpring1997refuelingoutageofNineMilePointUnit1,thenuclearcoreshroudrepairassemblies,installedduringthe1995outage,werefoundtobedegraded.Thedegradationconsistedofloosetierodsandfailedlowerspringcontactwedgelatches(retainerclips).ThisreportdescribestheresultsofthemetallurgicalevaluationperformedatGE'sVallecitosNuclearCenterlaboratoriestovalidatetherootcauseoftheretainerclipfailures.~~Therootcauseofthecontactw'edgelatchfailurewasdeterminedtobehighsustainedloadsappliedtotheundersideofthelatchnose(duetounacceptablemovementoftheshroudrepairassembliesduringplantoperation)resultinginanintergranularstresscorrosion(SCC)crackfractureofthecontactwedgelatch.CrackinitiationandgrowthoftheSCCfractureoccurredwithinonecycleofplantoperation.SuchcrackgrowthisconsistentwithlaboratorypredictionsofSCCpropagationratesofAlloyX-750intheBWRenvironmentunderhighsustainedloads.

GENEB13-01739-44DraftRevision0June1997CONTENTS

1.0INTRODUCTION

................................................................................................52.0SUMMARYe~~~oe~oo~oo~~~~~oo~~~~~~eeo~~~~ooooo~~~~~~~~~~~~oo~~~~~~~~~~~~~~'ooo~~~oo~~~~~~~~~~~~~~~~~~~eeee63.0BACKGROUND....................................................................................................73.1DESIGNDESCRIPTION3.2FIELDINSPECTIONS...................................3.3INITIALASSESSMENTOFFAILURECAUSE....~~~~~o~~~~~~~~~~~~~~~o74.0LABORATORYCHARACTERIZATIONOFCRACKS....................................104.1RECEIPTEXAMINATION....104.1.1RADIOLOGICALSURVEY4.1.2VISUALEXAMINATION.4.2SCANNINGELECTRONMICROSCOPIC(SEM)FRACTOGRAPHY......10......10...124.2.1350DEGREELATCHSEMFRACTOGRAPHY.4.2.290DEGREELATCHSEMFRACTOGRAPHY4.3OPTICALMICROSCOPY...12...13....134.3.1350DEGREELATCHMICROSCOPY.4.3.290DEGREELATCHMICROSCOPY..4.3.3166DEGREELATCHMICROSCOPY.4.4MATERIALSPROPERTIESVERIFICATION~~~~~~~~~~~~~~~~~~~~~~~~~~~13........14........14.154.4.1MATERIALCOMPOSITIONALANALYSIS4.4.2MICROHARDNESSTRAVERSE..............4.4.3MICROSTRUCTURALASSESSMENT.15...16....165.0ANALYSISOFRESULTS..................................................................~~~~eo~175.1FRACTUREMECHANISM.............5.2CRACKGROWTHCONSIDERATIONS........17.186.0ROOTCAUSEOFFAILURE...................................~~~~ooo~~~~~~~~~~~~~~~~~o197.0REFERENCES~~eooeooeoo~~~~ee~~oe~~~~~~~~oo~~~~~~~~~~eo~~eoo~~~~e~ooeeo~~~~~~~~eoe~~~~~eo~~~~eoeooo~eooeoooeeee20

GENEB13-01739-44Revision0June1997I.OINTRODUCTIONDuringtheSpring1997refuelingoutageatNineMilePointUnit1(NMP1),anomalieswerefoundwiththeshroudrepairhardware.Inparticular,irregularitieswerefoundwiththelowerspringcontactwedgelatches(alsoreferredtointhisreportandelsewhereas"retainerclips").Theshroudrepairhardwarewasinserviceforapproximatelytwoyears.Theanomaliesconsistedofloosetierodsandfailedlowerspringcontactwedgelatches.Thisreportdescribesthemetallurgicalevaluationsofthefailedcontactwedgelatches,andtheresultsofthoseevaluations.Inaddition,anon-failedwedgelatchwasincludedintheevaluation.Theanomalieswerefoundduringplannedvisualinspectionsoftheshroudrepairhardwareandduringtheplannedreplacementofashroudrepairassemblyat270degrees.

GENEB13-01739-44Revision0June19972.0SUMMARYAllfourshroudrepairassemblieswerefoundtohavelostverticalpreloadandthreeofthewedgelatchesthatpreventrelativemotionbetweenthelowerspringandthewedgeweredamaged.Onelatchhadfailedinservice(the90degreelatch),anotherfailedduringtheremovalprocess(the350degreelatch),andathirdhadvisualevidence,ofdamage(the270degreelatch).Thefourth(166degreelatch)hadnoevidenceofdamage.Similarwedgelatchesonthemid-supportsandontheupperspringswerefoundtobenormal.Thelowerspringlatchesaresimilarinphysicalfeaturestothe'upperspringandmid-supportlatchesbuthavedifferentappliedloadings.TherootcauseoFthelatchfailureandthetierodloosenessisrelatedtothedesignassumptionofslidingonthevesselsurface.RefertoreportGENEB13-01739-40(Reference1)forafulldiscussionofshroudrepairanomalies.ThisreportdescribestheresultsofthemetallurgicalevaluationperformedatGE'sVallecitosNuclearCenterlaboratoriestovalidatetherootcauseoftheretainerclipfailures.

3.0BACKGROUNDGENEB13-01739-44DraftRevision0June1997Theasfoundcondition,designdescription,andfieldinspectionresultsarediscussedinthissection.Alsoincludedistheinitialassessmentofthecauseoflatchfailure.3.1DesignDescriptionTheshroudrepairwasdesignedtostructurallyreplacethecircumferentialweldsinthecoreshroud.Fourassembliesareplacedapproximatelyuniformlyaroundtheshroud(azimuths90,166,270,and350degree).Eachassemblyfunctionstoverticallyholdtheshroudtotheshroudsupportconeandtohorizontallysupporttheshroudatthetopguideandcoreplateelevations.Inaddition,thereareotherhorizontalsupportsthatwouldpreventunacceptablehorizontalmovementofanyshroudcylindricalsegmentthatcouldbeproducedbyfailureofthehorizontalshroudwelds.Figure1showsanelevationviewofonesetofshroudrepairassemblies.Therearefoursuchsetsatazimuths90,166,270,and350degreesaroundthecoreshroud.Thetierodisthemaincomponentforreactingaxialloads.Thelowerspringisthelinearspringforsupportingtheshroudatthecoreplateelevation.ThelowerwedgeisacomponentthatwasmachinedbasedonactualsitemeasurementtofitbetweentheRPVandthelowerspringwithasmallcompressionofthelowerspringatroomtemperature.Thelatchisawishboneshapedpiece,intendedtopreventrelativemotionbetweenthelowerwedgeandthelowerspring.Figure2providesdetailofthelowerspringwedgelatchwithintheshroudrepairassembly.Similarlatchesarealsousedtopreventrelativemotionatthemid-supportandattheupperspring.Thelowersupportisanassemblythatconnectstheshroudrepairhardwaretotheshroudsupportcone.Thetierodnutisatthetopofthetierodandisusedtotightentheassembly.Duringinstallation,thetierodnutwastorquedtopreloadtheassembliestoassureminimaltightnessofcomponents.Themid-supportisusedtolimitrelativemotionbetweenthemiddleoftheshroudandtheRPV.Theupperspringisalinearspringforsupportingtheshroudatthetopguideelevation.Formoreextensivedescription,seeReferencel.

0 GENEB13-01739-44Revision0June1997~~~3.2FieldInspectionsThelowersupportwedgelatchat90degreeswasfoundbrokenandseparatedduringthevisualinspection.The"nose"pieceofthelatchwasmissingandlaterfoundonthelowersupportconeatapproximatelyazimuth330degrees.Figure3isaphotographofthebroken90degreelatch.BasedonanexaminationofphotographsofthefracturesurfacetakenattheNMP-1site,andIVVIvideotapes,thefailurewasjudgedtobenotconsistentwithafatiguemechanism.Inaddition,therewasnovisibleevidenceofplasticdeformation,whichwouldbenecessaryforasingleeventoverloadtypeoffailure.Thefailuresurfaceappearedtobeconsistentwithastresscorrosionfailureunderhighstress.Basedsolelyonthevisualinformation,astresscorrosionfracturewasbelievedmorelikelythananoverloadfracture.Videotapeinspectionoftheotherthreelowerwedgelatchesshowedthemalltobeintact,butthe350degreelatchappearedtobe"bent".Inaddition,thelowerspringwedgeshadevidenceoflocalhardcontactwiththewedgelatch,duetoverticalloadswithinthetierodassembly.SincethelatchesareAlloyX-750andthelowerspringwedgesareType316lowcarbonstainlesssteel,thelowerspringwedgeswillshowsurfaceimprintbeforethelatches.Thesimilarlatchesusedineachmid-supportassemblyandtwosimilarlatchesareusedineachupperspringassemblyallhadbeenvisuallyexaminedandallappearednormal.Becauseofdesigndifferences,theseotherlatchescannotbeloadedasseverelyasthelowerwedgelatches.ThecontactforcebetweentheRPVandtheshroudrepairismuchsmallerattheselocationsascomparedtothecontactforceatthelowerwedge.Inaddition,theselatchesarenotloadedduringplantheat-up.3,3InitialAssessmentofFailureCauseDuringnormalplantoperationthereareonlyafewsourcesofloadsontheshroudrepair.Theseareinstallation,differentialthermalandpressureexpansion,fluidflowanddeadweight.Thedeadweight,fluidflow,andinstallationstressesarelow.Themainforcesontheshroudrepairareduetodifferentialthermalexpansionbetweentheshroud,RPV,andshroudrepair,whichbothareintheverticalandhorizontaldirections.BasedontheinitialIVVIobservationsoftheloosetierodat270degreesandthefailureofthelatchat90degrees,differentpotentialcauseswerepostulated.Thesecauseswerepossiblevibrationleadingtoyieldingofthetierods,fatigueofthelatch,orotherunexpecteddisplacementscausingasingleeventfailure.EvaluationssolelybyIVVItechniquesandphoto

GENEB13-01739-44DraftRevision0June1997macrographsofthefracturefaceofthelatch,areofcourseinsufficientevidencetoestablishtheactualcauseoflatchfracture.Areviewofthestressanalysesshowedthatthetierodscouldnothavebeenoverloadedtoyield,andthefailuresurfacedidnotshowvisibleevidenceofplasticdeformationtypicalofasingleeventoverloadfailure.Thejagged,irregularfailuresurfaceofthebroken90degreelatchtendstoruleoutfatigueasapossiblefailuremechanism.'However,theevidenceobtainedbymacroscopicfieldobservationstronglysuggeststhatthelatchfracturewasduetoastresscorrosionmechanismratherthanafatigueormechanicaloverloadfailure.Thesurfacehastheirregularfeatureswithcharacteristicsofsecondarycracking,suggestiveofstresscorrosionunderhighstress.TheonlyknownsourceofhighstressisduetorestraintofdifferentialverticalmotionbetweentheRPVandthelowerspringwedge.IfthelowerspringwedgedidnotslideverticallyalongtheRPV,thenthedifferentialdisplacementmustoccurbetweenthelowerspringandthelowerwedge.Suchmovementwillcausehighstressinthelatch.SourcesofsuchdifferentialdisplacementaretheverticalloosenessofthetierodsandthedifferentialdisplacementsdiscussedinReference1.Therefore,therootcauseofthelatchfailureandthetierodloosenessisrelatedtothedesignassumptionofthecontactwedgeslidingonvesselsurface.

GENEB13-D1739-44RevisionDJune19974.'0LABORATORYCHARACTERIZATIONOFCRACKSDetailsofthemetallographicexaminationperformedonthewedgelatchesarepresentedinthissection.Thefocusoftheevaluationwastoperformareasonableamountofworktoprovideahighconfidence,technicallysupportableunderstandingofthecauseofwedgelatchfailure.ThreelowercontactwedgelatcheswereexaminedattheGeneralElectricVallecitosNuclearfacilityinPleasanton,California.Twofailedlatchesandoneundamagedlatcheswereexaminaed.4.1ReceiptInspectionThreelowerwedgelatches(90degree,166degree,and350degree)werepackagedina55galdrumpreparedasaTypeAradioactiveshipmentcontainerattheNineMilePointUnit1site,andtransportedtoGeneralElectric'sVallecitosNuclearCenter(GF;VNC)metallurgicallaboratoryforfailureanalysis.TheshippingcontainerwasprovidedbyGE-VNC.4.1.1RadiologicalSurveyUponreceiptatthemetallurgicallaboratory,thelatcheswereunpackagedintheGE-VNC-RHO(RemoteHandlingOperation)controlledcorriderarea.Aradiologicalsurveywasperformed.Resultsindicatedgamma+betaactivitytobeintherange(approx2R/hrcontact,and300mRat18inches)allowinghands-onevaluationprocedurestobeused.Followingradiologicalsurvey,thelatchesweredecontaminatedbyultrasoniccleaninginamild,dilutedCORPEXcleaningsolution,followedbydeionizedwaterrinsingandairdry.4.1.2VisualExaminationVisualexaminationanddocumentationofthesurfaceconditionwasperformedoneachlatch.Particularattentionwasappliedtoevidenceofplasticdeformation,andconditionofthefracture,surfaces.Directlowmagnificationphotographswerepreparedtodocumentcondition.TheresultsareprovidedinFigures3through6,and8through11.Figures3and4arephoto-macrographsof90degreelowerspringcontactwedgelatch,foundinthebrokenandseparatedcondition.Thenosepieceofthelatchwasfoundintheannulusregionofthereactor.ThisisthelatchfracturefacephotographedduringsiteIVVIactivities,usedtomakethepreliminaryassessmentthatthefracturewasprobablyduetoastress10

GENEB13-01739-44DraftRevision0June1997corrosionmechanism.Theirregularsurfaceconditionwassuggestiveofacorrosionrelatedmechanism.InFigure4itisnotedthatthefracturesurfaceisuniformlycoloredwithanoxidationcharacteristicofthatproducedbyexposuretotheBWRenvironment.Therewasnoevidenceofplasticdeformation,suggestingmechanicaloverloadwasnotacausitivefactor.Inaddition,itwasnotedthattheundersideofthelatch"nose"hadanoxidepatternsuggestiveofsustainedcontactduringservice.Figures5and6areclose-upphotographsofthe166degreelatch.Thislatchwasfoundintactandwithoutdamage.Figure6isanenlargedviewoftheundersideofthenoseregionofthelatch.Incontrasttothatobservedonthe90degreelatchdocumentedinFigure4,anabsenceofoxidepatterningisfoundonthislatchsuggestingnosustained'contactduringservice.Sincethe166degreelatchwasnotobviouslycracked,thenoseportionofthelatchwascutfromtheremainderofthelatchandexaminedundertheSEMatrelativelylowmagnification.Thistechniqueiseffectiveinlocatingsmallortightcracksiftheyarepresent.TheresultsareprovidedinFigure7.Figure7hastypicalviewsofthe'inside'ornerregion.Theexaminationrevealednocrackingintheareaofcrackinitiationasfoundontheotherwedgelatches.Figures8throughllareclose-upphotographsofthe350degreelatch.Thislatchwasreportedas"bent"intheIVVIreport,the"bend"beinglocatedattheundersideofthenose.Duringremoval,thelatchbroke,separatingintotwopieces.Figure8isanenlargedviewofthe350degreelatch,showingthelocationofseparation.Theseparationisthesamelocationasthefractureofthe90degreelatch,withtheimplicationthatthelatchwasnearlythrough-wallcrackedduringserviceandremovalhandlingresultedinthefinalseparation.Figure9showsasideviewofthebrokensegmentsofthe350latch,showinganabsenceofplasticdeformation.TheIVVIindicatedapossibledeformation-nowknowntobecausedbyayawningopenofanearlythroughwallcrack.Figure10isanenlargedviewofthe350degreelatchfracturefaces.Notethegradationofoxidecoloration,rangingfromdarkestbrownintheregionofcrackinitiation(oldestcracksurface)toalightbrownintheregionofthecracktip(recentcrackgrowthintheBWRenvironment).Theunoxidizedbandattheloweredgewascausedbyroomtemperatureductilefractureduringlatchremoval.Figurellisanenlargedviewofthefracturefaceandtheundersideofthelatchnoseofthe350degreelatch.Notethegraybandattheupperedgeoftheundersidesurface.Thisbandwascausedbysurfacecontactduringservice.Comparethisconditionwithphotosofthe166degreelatchinFigures5and6,whichshownopatternofcontactontheoxidesurface.

GENEB13-01739-44Revision0June19974.2ScanningElectronMicroscopic(SEM)Fractography4.2.1350DegreeLatchSEMFractographyScanningElectronMicroscopicFractography(SEM)wasperformedonthefracturefaceremovedfromthe350degreeand90degree-latches.The350degreelatchwasselectedforamorecomprehensiveevaluationbecausetheBWRservicecrackwasnotthroughwall,andthereforecontainedacracktip.Intheregionadjacenttothecracktip,thesurfacewasnearlyfreeofoxide,allowingclearimageryoffractographicfeatures.I'igures12through19providetheresults.The90degreelatchfracturefacewasstudiedtoconfirmthemechanismoffracturewasthesame.Figure12isanSEMviewat12Xofthefracturefaceofthe350degreelatch.Thislowmagnificationmacroscopicviewshowedsecondarycrackingassociatedwiththeprimaryfracture.ThisischaracteristicofSCCgrowth.ThisfigurealsoprovideslocationinformationforthehighermagnificationviewsofFigures13-16.Figure13isa300Xmagnificationviewofthefracturefaceintheregionofcrackinitiation.Seearrowlocation4inFigure12.Notetheintergranularnatureofthefracture,withminorplasticdeformationandmoderateoxidebuild-up.Figure14isthesamefracturefaceatamagnificationof200Xinthemid-fractureregion.Notetheintergranularcharacteristicofthesurface,withmoderateoxidebuild-up.Thisislocation3inFigure12.Figures15ak,b(Location2inFigure12),arefracturefaceviewstakenat200and300Xoftheregionnearthecracktip.Notetheslightbuild-upofoxide,indicatingrecentgrowthintheBWRenvironment.Figure16containsviewsofthefractureface(300Xand1000X)atlocation5inFigure12.Thisistheregionofductilerupturewhichoccurredatroomtemperatureduringlatchremoval.Thecentralregionofthe350degreelatchfracturefaceisshowninFigure17.Thelefthandedgeofthefracture(arrowlocation1intheFigure)wastheregionoflowtemperaturefractureduringlatchremoval.Thisfigureprovideslocationinformationforthehighermagnificationviewsoffigure18.Figure18contains200Xand300XviewsofthefracturesurfaceshowninFigure17atlocation1.NotetheIGSCCcharacter,andtheonlyveryslightoxide.Thisregionisnearthecracktip.Location2hasappearancethesameasFigure14.Figure19isahighmagnification(2000X)viewofthefracturefaceofthe350degreecontactwedgelatch.TheareaselectedisthecentralregionoftheviewofFigure15a,andwas12 0

GENEB13-01739-44DraftRevision0June1997selectedbecauseitwasrelativelycleanofsurfaceoxide.Featurescharacteristicofafatiguefracturewerenotobserved.Anintergranularfailuremodewasobserved.4.2.290DegreeLatchSEMFractographyScanningElectronMicroscopicFractography(SEM)wasalsoperformedonthefracturefaceremovedfromthe90degreelatch.'Whilethe350degreelatch"wasselectedforamorecomprehensiveevaluationlatchbecausetheBWRservicecrackwasnotthroughwall,the90degreelatchfracturefacewasstudiedtoconfirmthemechanismoffracturewasthesame.Figures20through23providetheresults.Figure20isaSEMview(12X)ofthefracturefaceofthe90degreecontactwedgelatch.Thislowmagnificationmacroscopicviewshowssecondarycrackingassociatedwiththeprimaryfracture.Aswasfoundonthe350degreewedgelatchfractureface,thisischaracteristicofSCCgrowth.Thisfigurealsoprovideslocationinformationforthehighermagnificationviewsofthe90degreewedgelatchfracture,Figures21-23.Figure21isa200Xviewofthefracturefaceintheareaofcrackinitiation.ThecrackingisintergranularwithheavyoxidebuildupcharacteristicofIGSCC.Figure22isa200Xviewoftheregionnearthesiteoffinalseparationofthe90degreewedgelatch.Thecrackingisclearlyintergranular,withlessoxidebuildupthanseeninFigure21.Figure23isa800XviewofthecenteroffracturefaceofFigure22.Notetheoxidebuildupandobscuringofthefracturefacedetail.4.3OpticalMicroscopy4.3.1350DegreeLatchMicroscopyAsinglesectionwaspreparedforopticalmicroscopicevaluationofthe350degreelatchfracture.Thesectionwaslocatedasindicatedin1'igure24.Thislocationwasselectedasitcapturedsecondarycrackingaswellastheprimarysurfacefeatureofcrackinitiation,growth,cracktip,androomtemperatureductileseparation.Theplaneofpolishisperpendiculartotheplaneoftheservicefracture.Figure25isanas-polished,andetchedviewofthefracture.Figure26containsopticalmicroscopicviewsofthelatchfailure.Photoa.istheregionofthecrackmouth(initiation).Photob.isthemid-fractureregion,andc.istheregionoffinalseparationcharacterizedbytransgranularductilerupture.TheupperleftphotographinI'igure27showssecondarycrackingcharacteristicofIGSCC.Magnifiedviewsofthecrack P

GENEB13-01739-44DraftRevision0June1997arenotedinthelowerphotoofFigure27.ThiscrackmorphologyischaracteristicofIGSCC.Figure28isahigh(250X)viewofthefractureintheregionofthecrackinitiation.Evidenceofminorcoldworkwasobserved.Figure29isahighmagnification(250X)viewofthemid-fractureregionofthe350degreewedgelatch,clearlyshowingtheIGSCCnature.Figure80showshighmagnification(250X)viewoflatchfracturefaceinregionoffinalseparation.Thefinalseparationoccurredbyductilerupture,andhasanassociatedplasticdeformation.TheobservationisfullyconsistentwiththeresultsofSEMfractography,asseenintheviewsofFigure16,4.8.290DegreeLatchMicroscopyAsinglesectionwaspreparedforopticalmicroscopicevaluationofthe90degreelatchfracture.Thesectionwaslocatedandpreparedinmannersimilartothatusedforthe350degreelatchsample.Thislocationwasselectedasitcapturedsecondarycrackingaswellastheprimarysurfacefeaturesofcrackinitiation,growthandfinalseparation.Theplaneofpolishisperpendiculartotheplaneoftheservicefracture.Figure31isanas-polished,andetchedviewofthefracture.Figure32containsopticalmicroscopicviewsofthelatchfailure.Photoa.istheregionofthecrackmouth(initiation).Photob.isthemid-fractureregion,andc.istheregionoffinalseparation.Therewasnotransgranularductileruptureassociatedwiththislatchfracture.Figure33showssecondarycrackingcharacteristicofIGSCC.Figure34isahigh(250X)viewofthefractureintheregionofthecrackinitiation.Noteevidenceofminorcoldwork,similartothatfoundonthe350degreelatch.Figure35isahighmagnification(250X)viewofthemid-fractureregionofthe90degreewedgelatch,clearlyshowingtheIGSCCnature.Figure36isaviewofaportionofthesecondarycrackingnearthemouthofthesecondarycrack,withsignificantoxidebuildup.ThisbuildupischaracteristicofacracksurfaceexposedtotheBWRenvironmentforsometime.Bycomparison,the350degreelatchwasamore"recent"failure.4.8.8166DegreeLatchMicroscopyFigure37hascross-sectionalviewsoftheuncracked166degreewedgelatch.Notethelackofincipientcrackingorplasticdeformationintheareaofcrackinitiationonthe90and350degreelatches.14

GENEB13-01739-44Revision0June1997~~4.4MaterialsPropertiesVerificationThelowercontactwedgelatcheswerefabricatedtoGEDrawing112D6560ofAlloyX750:ASTMSpecificationASTM-B-637Type3,HeatHT¹51072-2,asindicatedintheAppendixA-"AlloyX-750CertificateofConformance/Compliance/CMTR."HeatTreatmentProcedurewasinaccordancewithGE-SAP-AH-1Revision2,dated10/25/1994,andGI':NESpecification,P50YP107/Attachment1.Thesedocumentsindicateanagehardeningheattreatmentat1300degreesFfor201/2hours,followedbyafanaircool.Thematerialofafailedwedgelatchwastestedbyvariousmeanstoassessthecorrectnessofmaterialcompositionandheattreatment.Theresultsaredocumentedinthefollowingparagraphs.4.4.1MaterialCompositionalAnalysisInitialcompositionalanalysisscreeningwasperformedatthetimeoftheSEMfracturesurfacestudy.Figure38isEDS(EnergyDispersiveX-raySpectroscopy)datausedtoqualitativelycheckcompositionofthelatchmaterial.Thescanwaspreparedonarelativelyclean(lowoxidation)regionofthefractureface.ThedataareconsistentwithAlloyX-750.'Furtheranalysiswasperformedbyusingadirectcoupledplasmaspectrographicquantitativeanalysistechnique.MoreaccuratethantheSEM/EDSmethod,theresultsofthisanalysiswasusedtocomparethecompositionwiththeASTM-B-637-89,Type3designatedintheGEPurchaseSpecification,aswellasthecheckanalysisprovidedintheCMTRfortheappropriatelatchheatHT¹51072-2.ThesecomparisonsarelistedinFigure39.Thesampleforthespectrographicanalysiswaspreparedfroma1gramportionofthemetallographicspecimenremovedfromthe350degreewedgelatch.Toensuretheremovalofsurfacecontamination,thesamplewasalternatelyetchedwithconcentratedhydrochloricandnitricacidsuntilfreshlyexposedmetalwasobservedonallsurfaces.Thesamplewasthenrinsedindeionizedwater,thendried.Thecleansamplewasthenweighed,thendisolvedinapproximately20mLconcentratednitricacidand2mLhydrochloricacidforeachgramofmetal.Thedissolutionwascarriedoutbyheatingtonearboilingina100mLTeflonbeakercoveredwithaTeflonwatchglass.ThesolutionwasthenanalyzedwithaSpectraspanIIIplasmaemissionspectrometerequipedwithanADaMdataacquisitionandcontrolsystem.StandardsteelmaterialsusedtocalibratethespectrometerresponsewereobtainedfromtheNationalBureauofStandards(NBS),nowknownastheNationalInstituteofStandardsandTechnology.Theresultsobtainedinthisanalysis,providedinFigure39demonstrategoodagreementwiththecertifiedvalues.ItisconcludedthecompositionofthewedgelatchmaterialisconsistentwithAlloyX-750.15 0

GENEB13-01739-44Revision0June19974.4.2MicrohardnessTraversesMicrohardnessmeasurementswereperformedonthepolishedandetchedsampleofthe350degreewedgelatchoriginallyusedforopticalmicroscopiccharacterizationoflatchcracking.Figure40isaphoto-macrographofthemicrohardnessimprints.MeasurementsweremadeintheKnoopscale,witha500gramload.AverageKnoopreadingswereapproximately373I&oop,correspondingtoareadingofapproximately346ontheHBscale.Forthismaterial,I&oopreadingsrangingfrom292to391arespecified(or267to363ontheHBscale).Nohardnessgradients,orincreasesinreadingsnearthefractureedge,werefound.Theseobservationsdemonstratethefracturefailurewasnotassociatedwithplasticdeformation,orductileoverload.TheseresultsareconsistentwiththeresultsofopticalmicroscopyandSEMfractography,andconsistentwiththeheattreatment.4.4.3MicrostructuralAssessmentBasedontheHeatTreatmentrecordforHt451072-2,asdocumentedintheCMTR(AppendixA)thematerialwassuppliedintheAnnealed(1975+/-25F)condition,andagehardenedat1300F+/-15Ffor201/2hours,followedbyremovalfromthefurnaceandafanaircool.Opticalmicroscopyofatensiletestspecimenofthisheat,withthisannealcondition,showsagrainsizeof7.0.Highmagnificationopticalmicroscopicviewsofsamplespreparedfrom90and166degreewedgelatchesFigures41and42showamicrostructurecorrectandappropriateforthismaterialandheattreatcondition.16 0

GENEB13-01739-44Revision0June19975.0ANALYSISOFRESULTS5.1FractureMechanismThepreceedingsectionsofthisreporthavedocumentedthekeyevaluationevidenceassociatedwiththemicrostructuralandfractographicfeaturesofthelatchfailure.Theyaresummarizedhere(andsummarizedinTable1):1.Thewedgelatchmaterialisofcorrectcomposition(AlloyX-750),andisasspecified.Theheattreatmentwascorrectandresultedinappropriatehardnesslevels.2.Thereisonlyminorevidenceofplasticdeformation(atthepointofcrackinitiation),asshownbyopticalmicroscopy,indicatingthefailurewasnotduetoasingleeventoverload.Thisstatementisfurthersupportedbytheabsenceofmicrohardnessgradientsinthefractureregion.3.Thefractureisintergranular,characteristicofIGSCCfoundinBWRinternalcomponents.4.Crackinitiationoccurredunderthelatchnoseatthetransitionfroma200milthicksectiontoamuchthicker"nose"section.5.Thoselatchesthatfailedhadanoxidepatternontheundersideofthenose,indicatingcontactduringservice.Theuncrackedlatch(166degreelatch)didnothavetheoxidecontactpattern.ConfirmationoftheabsenceofcrackingwasprovidedbybothSEMsurfaceimageryaswellasbyopticalmicroscopy.Withthisevidence,itisconcludedthatthelowerspringcontactwedgelatchesfailedasaresultofIntergranularStressCorrosionCrackingofamaterialhavingaknownsusceptibilityunderhighstressconditions.Therootcauseofthefailureofthecontactwedgelatchfailurewasdeterminedtobehighsustainedloadsappliedtotheundersideofthelatchnose(duetounacceptablemovementoftheshroudrepairassembliesduringplantoperation)resultinginanintergranularstresscorrosioncrackfractureofthecontactwedgelatch.CrackinitiationandgrowthoftheSCCfractureoccurredwithinonecycleofplantoperation.17

GENEB13-01739-44Revision0June19975.2CrackGrowthConsiderationsTheresultspresentedinReference2(IntergranularStressCorrosionCrackingPropagationRatesofAlloyX-750intheBWREnvironment,dated25March1977)indicatethatalthoughAlloyX-750isasuitablestructuralmaterialforBWRapplications,andthefactthattheIGSCCfailedwedgelatchesweremanufacturedfromAlloyX-750withappropriatecomposition,heattreatmentandmechanicalproperties,demonstratethatAlloyX-750is'notimmunetoIGSCCintheBWRenvironment.Themeasured(fracturemechanicsspecimens)andcalculated(CBBspecimens)AlloyX-750crackgrowthratesindicatethatatmoderatetohighstressintensities,AlloyX-750,evenheattreatedtoobtainitshighestresistancetoIGSCCintheBWRenvironment,cansufferrapidintergranularcrackgrowth.ThesemeasuredandcalculatedAlloyX-750crackgrowthratesarereadilyhighenoughtoresultinfailureofthe200milthickwedgelatchwithinonefuelcycle,assupportedbythedataofReference2.18 00 GENEB13-01739-44DraftRevision0June19976.0ROOTCAUSEOFFAILUREThemostprobablerootcauseofthelowerspringcontactwedgelatch(retainerclip)failurewasdeterminedtobehighsustainedloadsappliedtotheundersideofthelatchnose(duetounacceptablemovementoftheshroudrepairassembliesduringplantoperation)resultinginanintergranularstresscorrosioncrackfractureoftheretainerclip.CrackinitiationandgrowthoftheSCCfractureoccurredwithinonecycleofplantoperation.SuchcrackgrowthisconsistentwithlaboratorypredictionsofSCCpropagationratesofAlloyX-750intheBWRenvironmentunderhighsustainedloads.19

GENEB13-01739-44Revision0June19977.0REFERENCES7.1GENEB13-01739-40,"NineMilePoint1-ShroudRepairAnomalies",April19977.2"IntergranularStressCorrosionCrackingPropagationRatesofAlloyX-750intheBWREnvironment",25March1997.B.M.Gordon,CorrosionTechnologyReport.20

GENEB13-01739-44DraftRevision0June199760~8lljLII3.eaaoauII.IIIOi6IBtXk90Kl'PPPRSUI>PORF//~~UPPERSPRING~TIERon'~s-rerSUPIORTTll'.ii-'llKIIOSUPPORT('l/RIN(lsI(1I.OOiiiiNO((sr/)-TIjCHPIIINGLOWERSPRINGlAWIIRSPRLIG0~IICl.tVISPIN1FJ---CLL'VISPINI.0%F.RSUPPORTTOG(II.I'IOI.TZO(;CI.E130I,T~pire1.ShroudRepairAssemblies21 0

GENEB13-01739-44DraftRevision0June1997OWERSPRINGVESSELLLLATCH5'EFLOWERWEDGEFi<nu~e.ShroudRepairLowerSupportConfiguration22

GENEB13-01739-44DraftRevision0June1897trl1F~ireS.Photo-macrographof90degreelowerspringcontactwedgelatch,foundinthebrokenandseparatedcondition.ThenosepieceofthelatchNfasfoundintheannulusregionofthereactor.

GENEB13-01739-44DraftRevision0June1997(>>FIFIF(I'd~,V>>4IIIF~ire4.Enlargedviewofthe90degreecontactwedgelatchfracturesurfaces.Noteuniformoxidecolorationoffracturesurfaceandabsenceofplasticdeformation.Oxidepatternonundersideoflatch"nose"indicatescontactduringservice.~~~

GENEB13-01739-44DraftRevision0June19970Ps.,'ttF~ire6.Contactwedgelatchremovedfromthelowerpositionofthe166degreetierodassembly.Clipwasintactandwithoutirregularity.25

GENEB13-01739-44DraftRevision0June1997sa,)+--rF~ire6.Enlargedviewofundersideof166degreecontactwedgelatchnose.Notetheabsenceofoxidepatternindicatingnocontactduringservice.ComparewithFigure4.26

GENEB13-01739-44DraftRevision0June1997CornerrciiCornerIaIL5~F~inre7.Typicalviewsof"insidecorner"regionof166degreecontactwedgelatchbySEMimagery,performedtoidentifypossiblecracking.Themethod,usedinplaceofPT(penetranttesting),revealednocrackinginareaofcrackinitiationasfoundoncrackedwedgelatches.27

GENEB13-01739-44DraftRevision0June1997F~inreEnlargedviewof350degreecontactwedgelatch,showinglocationofseparation.Thenoseseparatedduringlatchremoval.

GENEB13-01739-44DraftRevision0June1997lvpv,lQ~I~>c)Ir~FtureSideviewofbrokensegmentsof350degreecontactwedgelatcit,showingtheabsenceofplasticdeformation.TheIVVIphotoindicatedapossibledeformation-nowknowntobecausedbyayawningopenofanearlythrough-sectioncrack.29

GENEB13-01739-44DraftRevision0June1997IAf'-gd<Pt.Elf'ggfgg3"Egd5I'ddddgdg3dI'.Ngradationofoxidecoloration,rangingfromdarkestbrownintheregionofcrackinitiation(oldestcracksurface)toalightbrownintheregionofthecracktip(recentcrack)inBWRenvironment.Theunoxidizedbandoftheloweredgewascausedbyroomtemperatureductilefractureduringlatchremoval.30

GENEB13-01739-44DraftRevision0June1997IgdiI'0fddid5d""5350degreecontactwedgelatch.Notethegraybandattheupperedgeoftheundersidesurface.Thisbandwascausedbysurfacecontactduringplantoperation.ComparewithFigures4and6.

GENEB13-01739-44DraftRevision0June1997llllw~8~3FRACTUREFACEATEND"A"~Fiure12.SEMview(12X)fracturefaceof$50degreewedgelatch.Thislowmagnificationmacroscopicviewshowssecondarycrackingassociatedwiththeprimaryfracture.ThisischaracteristicofSCCgrowth.Thisfigurealsoprovideslocationinformationforthehighermagnificationviewsofthefollowingfourfigures.End"A"isattheleftendofthelefthandfractureseeninFigure10.

GENEB13-01739-44DraftRevision0June1997et~*faaaFuture1$.Fractureface(800x)inregionofcrackinitiation-Arrowlocation(4)inFigure12.Noteintergranularnatureoffracture,withminorplasticdeformation,andmoderateoxidebuildup.

GENEB13-01739-44DraftRevision0June19974&(5555~Fiure14.Fractureface(200X)inmid-fractureregionof850degreewedgelatch.Noteintergranularcharacteristicofsurface,withmoderateoxidebuildup.Location(8)inFigure12.

II GENEB13-01739-44DraftRevision0June19975s'558Js5555IFiure15a8cb.Fracturefaceviews(200and300X)ofregionnearcrackinitiationinthe850degreewedgelatch.Noteslightbuildupofoxide,indicatingrecentgrowthinBWRenvironment.(Location(2)inFigure12.)

GENEB13-01739-44DraftRevision0June1997r14~':fla~..i;,S:tt,$:~':fJa~r..i;,S:tt4t(i0)g.tF~jF5fjF>)yQ'Pi,rp1jFf~f~FfI~Fiure16.Vietcaoffractureface(800and1000X)atlocation(6)inFigure12.Thisistheregionofductilerupturewhichoccurredatroomtemperatureduringthe850degreewedgelatchremoval.

GENEB13-D1739-44DraftRevisionDJune1997vjtP~Fiurei7.SEMview(12X)ofcentralregionoffracturefaceof850degreewedgelatch.Thelefthandedgeofthefracture(arrow1)isregionoflowtemperaturefractureduringlatchremoval.Thefigureprovideslocationinformationforthehighermagnificationviewsofthefollowingfigures.

nH GENEB13-01739-44DraftRevision0June1997fo+rr5550~F~iure18.SEMviews(200and800X)offracturesurfaceshowninFigure17atlocation(I).NoteIGSCCcharacter,andonlyveryslightoxide,sincethislocationisnearcracktip.

GENEB13-D1739-44DraftRevisionDJune1997g~iurei0.Highmagnification(2000X)viewoffracturefaceof850degreecontactwedgelatch(Figure15a).Featurescharacteristicofafatiguefracturearenotobserved.Anintergranularfailuremodeisindicated.

GENEB13-01739-44DraftRevision0June1997AqketIcia?P,t-t~IFuture20.SEMview(12X)ofthefracturefaceof90degreecontactwedgelatch.Thislowmagnificationmacroscopicviewshowssecondarycrackingassociatedwiththeprimaryfracture.Aswasfoundonthe850degreewedgelatchfractureface,thisischaracteristicofSCCgrowth.Thisfigurealsoprovideslocationinformationforthehighermagnificationviewsofthefollowing90degreewedgelatchfracturefigures.40

GENEB13-01739-44DraftRevision0June1997h'~iure2i.Fractureface(200X)inregionofcrackinitiationofthe00degreewedgelatch.ArrowlocationonFigure20.Crackingisintergranular,withheavyoxidebuildup-comparewithFigure13,thecomparableviewforthe350degreewedgelatch.41

GENEB13-01739-44DraftRevision0June1997~W~sAIjtt+r.s%rtarvFuture22.Fracturefaceview(200X)ofregionnearsiteoffinalseparationofthe90degreewedgelatch.(ArrowO~locationonFigure20)CrackingisclearlyIntergranular,withlessoxidebuildupthanseeninFigure21.'gjwgsrirs2Sgs~rFiure23.800XviewofcenteroffracturefaceofFigure22.Noteoxidebuildupandobliterationoffracturefacedetail.

H,Iu GENEB13-01739-44DraftRevision0June1997e4>>tCUTHEREOI~4FRACTUREFACEMOUNT,POLISHANDETCHTHISFACEF~inre24.Sketchofsectioninglocationforopticalmicroscopy-850degree~~~wedgelatch.

GENEB13-01739-44DraftRevision0June1997I<p'2t.>>Isla2t&Pl*s*FINALSEPARATIONINITIATION~Finre5.As-polishedandetchedviews(20X)of850degreelatchsection.PlaneofpolishisperpendiculartofracturefaceatlocationindicatedinFigure24.

GENEB13-01739-44DraftRevision0June1997St@~tt<<\+ps"6tft.iIoREGIONOFCRACKMOUTH(INITIATION)128XDf'-MIDFRACTUREREGION-NOTESECONDARYIGSCCCRACKS.128Xc.REGIONOFFINALSEPARATIONTRANSGRANULARDUCTILERUPTURE.128X~Fiure6.Viewsoffracturebyopticalmicroscopy-650degreewedgelatch

GENEB13-01739-44Revision0June1997selectedbecauseitwasrelativelycleanofsurfaceoxide.Featurescharacteristicofafatiguefracturewerenotobserved.Anintergranularfailuremodewasobserved.4.2.290DegreeLatchSEMFractographyScanningElectronMicroscopicFractography(SEM)wasalsoperformedonthefracturefaceremovedfromthe90degreelatch.-'Whilethe350degreelatchwasselectedforamorecomprehensiveevaluationlatchbecausetheBWRservicecrackwasnotthroughwall,the90degreelatchfracturefacewasstudiedtoconfirmthemechanismoffracturewasthesame.Figures20through23providetheresults.Figure20isaSEMview(12X)ofthefracturefaceofthe90degreecontactwedgelatch.Thislowmagnificationmacroscopicviewshowssecondarycrackingassociatedwiththeprimaryfracture.Aswasfoundonthe350degreewedgelatchfractureface,thisischaracteristicofSCCgrowth.Thisfigurealsoprovideslocationinformationforthehighermagnificationviewsofthe90degreewedgelatchfracture,Figures21-23.Figure21isa200Xviewofthefracturefaceintheareaofcrackinitiation.ThecrackingisintergranularwithheavyoxidebuildupcharacteristicofIGSCC.Figure22isa200Xviewoftheregionnearthesiteoffinalseparationofthe90degreewedgelatch.Thecrackingisclearlyintergranular,withlessoxidebuildupthanseeninFigure21.Figure23isa800XviewofthecenteroffracturefaceofFigure22.Notetheoxidebuildupandobscuringofthefracturefacedetail.4.8OpticalMicroscopy4.8.1850DegreeLatchMicroscopyAsinglesectionwaspreparedforopticalmicroscopicevaluationofthe350degreelatchfracture.ThesectionwaslocatedasindicatedinFigure24.Thislocationwasselectedasitcapturedsecondarycrackingaswellastheprimarysurfacefeatureofcrackinitiation,growth,cracktip,androomtemperatureductileseparation.Theplaneofpolishisperpendiculartotheplaneoftheservicefracture.Figure25isanas-polished,andetchedviewofthefracture.Figure26containsopticalmicroscopicviewsofthelatchfailure.Photoa.istheregionofthecrackmouth(initiation).Photob.isthemid-fractureregion,andc.istheregionoffinalseparationcharacterized-bytransgranularductilerupture.TheupperleftphotographinFigure27showssecondarycrackingcharacteristicofIGSCC.Magnifiedviewsofthecrack I~$Npll'I0 GENEB13-01739-44DraftRevision0June1997rtt128Xrr~*~sa~vtt250X~Finre27.Secondarycracking-IGSCC.MagnifiedviewsofcracknotedinFigure25(upperphoto).ThiscrackmorphologyischaracteristicofIGSCC.

0 GENEB13-01739-44DraftRevision0June1997j08I~Fiure28.Highmagnification(250X)viewoffractureinregionofcrackinitiation-850dereewedelatch.Noteevidenceofminorcoldwork.5R,~Fiure29.Highmagnification(250X)viewsofmidfractureregionof550degreewedgelatch,clearlyshowsIGSCCnature.

GENEB13-01739-44DraftRevision0June1997v~v~<<WI~Fiure$0.Highmagnification(250X)viewof850degreelatchfractureedgeinregionoffinalseparation.Thefinalseparationoccurredbyductilerupture,andhasanassociatedplasticdeformation.TheobservationisfullyconsistentwiththeresultsofSEMfractography,asespeciallyseenintheviewsofFigure16.

GENEB13-01739-44'raftRevision0June1997avv;j'V'v$5.rtas)..]jl'P-rrrr+,0IIn,'."-,ase~~dref.s~4,.t~,.P,e~>g$,c.rt,..,....),,f,f,.y,vFFjd,4....l,<,,~/P(,@qit'p'vengrrrasff*P~inreSl.Etchedview(20X)of90degreecontactwedgelatchsection.PlaneofpolishisperpendiculartofracturefaceindicatedinFigure20.Notesecondarybranchcracking,andcomparewithviewof850degreelatchsectionofFigure25.49

GENEB13-01739-44DraftRevision0June1997a.REGIONOFCRACKMOUTH(INITIATION)128Xb.MID-FRACTUREREGION-NOTESECONDARYIGSCCCRACKS.128Xc.REGIONOFFINALSEPARATION-IGSCC,WITHOUTDUCTILERUPTURE.128XFigure~S.Viewoffracturebyopticalmicroscopy-90degreewedgelatch.128K50 0r GENEB13-01739-44DraftRevision0June1997128X-<<c1':<<,r'ir<<<<r<<250XF~ire99.Secondarycrackinginfractureof90degreecontactwedgelatch-IGSCCnatureissameasthatobservedin350degreelatch.ComparewithFigure27.51 0

GENEB13-01739-44DraftRevision0June1997jfi~Hre54.Highmagnificationview(250X)offractureinregionofcrackinitiationof90~~~~~~~~~degreewedgelatch.Noteevidenceofminorcoldwork.Iv~Fire55.Highmagnification(250X)viewofmitt-fractureregion,clearlyshowingIGSCCnature.52

eGENEB13-01739-44DraftRevision0June1997reee=~Fire56.Secondarycrackinginregion5ofFigure81,withoxidebuildup,characteristicofexposuretotheBWRenvironment.

GENEB13-01739-44DraftRevision0June1997h128X20X~Fire87.Cross.sectionalviewsofnncracked166degreewedgelatchNote.lackofincipientcrackingorplasticdeformationinareaofcrackinitiationonthe90degreeand850degreelatches.54

GENEB13-01739-44DraftRevision0June1997SSQ:>TI0TN-5588GE-VNCCui-soi-:8.888keV=8ROITUE22-RPR-9714:56C8>I.888:i.918C..N""'L'"'"iINNPS58tillliltRII~EI/INonnali2edEternentatWt%OAO1.553.0516.099.3567.56ASMSpecificationstnconeiX-7500.71.0g.515.57.073.0Future88.EDS(EnergyDispersiveX-raySpectrum)datausetequalitativelycheckcompositionoflatchmaterial.Scanwaspreparedonarelativelyclean(lowoxidization)regionofthefractureface.ThedataareconsistentwithAlloyX-750.

GENEB13-01739-44DraftRevision0June1997CrX.750NominalComposition15.5GE-PurchaseSpecificationASTM-B-'637-89Type314.0-17.0CMTRHTN51072-215.40EDS(SEM)CompositionAnalysis18.09DirectCoupledPlasma'uantitativeAnalysis15.1Ni73.070.00min71.6367.5671.5Co0.07Mo1.00.7-1.200.941.551.02.52.25-2.752.403.052.4AlFe0.77.00.040.4-1.005.00-9.000.08max0.738.140.0530.49.35N/A1.1'withinspeconcheckanalysis8.9N/ACu0.25max0.50max0.02F~ire$9.X750ContactWedgeLatch-MaterialCompositionalAnalysisWt%56 t

GENEB13-D1739-44DraftRevisionDJune19973P.""<<<<W>>.>>,.'k'>">>'>>~,t--~'>";,'e>>,"<<s~,j20XF~ire40.Etchedviewof050degreelatchsection(sameviewasFigure20)showingmicrohardnessimprints.MeasurementsinKnoophardnessscale,with500gload.Avg.878Knoop(292-891Knoopspecified)846HB(267-868HBspecified)

GENEB13-01739-44DraftRevision0June19971~o~e>Ieenee~~Ftre41.Highmagnification(1000X)viewof90'broken)wedgelatchmicroatrnctnre.ThestructureistypicalofacorrectlyheattreatedX750wedgelatchmaterial.58

GENEB13-01739-44DraftRevision0June1997vi~pire42.Highmagnificationopticalmicroscopicviewofuncracked166degreewedgelatch.

GENEB13-01739-44DraftRevision0June1997Test/WedgeLatchFieldvisualinspectionLab-visualexaminationOpticalmicroscopySEMfractographyMaterialpropertiesIjHdntttransverseMicro-structureFailuremode90DegreeNosepiece"missing"NoseseparatedLoadcontactpatternonundersideofnoseIGSCCnatureNocoldworkIntergranular-heavyoxideHeat¹HT¹51072-2AsexpectedforspecifiedheattreatmentIGSCC-initiationtofinalseparation16flDegreeUn-damagedNo"load"contactpattern,Uncracked-bySEMNotperformed(nocrackingfound)Notperformed(nocrackingfound)Heat¹HT¹51072-2Un-cracked350DegreeNosepiece"bent"Noseseparated(duringremoval)"Load"contactpatternonundersideofnoseIGSCCnatureMinorcoldworkatfinalseparationIntergranular-light-to-moderateoxideHeat¹HT¹51072-2ConsistentwithheattreatmentNominalpropertiesNogradientsIGSCCwithductilefinalseparationTable1.SummaryofAnalyticalTestResults-NMP-Tierodcontactwedgelatchfailures(270degreewedgelatch-notexamined)60 0

AppendixAAlloyX-750CertificateofConformance/Compiiance/CMTR

IIP4%w&HIimam-cv-viinvvcavriiluui.in@Qri."vliiLLQlblrivrtNNv.iIlcbaaliIvbUI.UCSF'ECIPJTYALLOYPROCESSINGCOMPANY,INC.POBox44006iPNsdvtgh,PA15239~(442)327-3838~FAX(412)32T<716INDUSTRIALHEATTREATINGMETALPROCESSINGCERTIFICATIONDate:Customer.Attn."Deember10,1994ToolingSpecialists,inc.POBox828Latrobe,PA15650KimParabaughCustomerOrderNumber:MateriaLXTGO:Alii-B-637Type3OurOrderNumber.4956-3Lot~3TS31739 51-6839{Gi=PO529-947749AT)Quantify8Part:5springre~erdwg.11206555HT'1071-324springretainer.dwg.112D6551HT&1074-I24screwtopsuptdwc.112D6558lt4HT&22861Dwasherjackbolt.dwg.112D6553HT&27945screwde.i1i2D6558lT1HTW27945boltjackdwg.112D65521T1HTP322865latchQwc.112D6560lT1HT451072-215latchdwg.51206560lT2HT~51072-2GOscrew'wg.1i2D6558lt6hi~32794Treatment:HeatTreatProcedure{Gc-SAP-AH-1REV2),dated10/25/948GE-NE.SPEC.PGOYP107/Attachmnt1:Agenardened13;).'oi={-:/-15oF)201/2hrs.RemoveandfanahmoL10CFR21appliesDateofTreatmenti2/9/94/5)12/10/94.SpecialtyAlloyProcemingCernpany,inc.projectEngineer345i~FR28'9714:524125374968PAGE.82'

I'IhPCCJ2(I0NJPPCIJChlllllWI>auIvs~s~aivrawywavvs~aaw~vrNR-20-97THUOZ'S4PNTGOLENGSPECEALESTSENC.FAXNO.4125374960P.03Casczae=-MBQSZHATZONckLr~GYSZKVTZ~,ZRC-900~US~~~>D~~//CXMTON,NC28328Ca~acfCm~a~ce/Coupl'nce/~101,0Dat.9/13/94Ser=.a2.Ea.38844DOazDC2'01316matariaZzeeM~ze~emenmorvcr~H)numb'.-528W4T398TGZNUcBR~6Z.~~C~~W302MS&a3kCMSWD~GO7PBDSSZL23.M~406Descpt'nPiecesSpec"'aMonQuad,a121/4"X~>>"X64"ROXLcZKLR~3637c39N07750PBZVMTON121/4"X15~X76"3DLLiZKLRAF-3637-69'07750~KRE~ZOH21/4"XM~"X128"ROLLSMRM~367-89i707750TYMCM1ON221/4"X15"X64"ROXZrZBAR~~M37-B9N07750~~C:SZONHeat4/yeahCsee33233.3w3%REX3e)2Q13%JW3ZX51072-2ZTZ51072-2~nat:arian'ashaensnnnlied.inaccordancewitJxDuSosaHat'cna1MercyS~ices,Znc.Qua~~~Sys~P~gzanzRav.3,cia~06-21-94incomate.fanceM~1oc~oAPP.3.Zhacon~+aoEMemaoz=azacoxrac-anCac~~and,""eresul--axeinconn'iance.~">~~>ma~a1spec.<ication,+~cocba,and.tJxacns~zznxrchaseoz~10CZ321Q~6~'T+KIT3~CKLSAHHELLiZ2Z1975+/-25DEG78HZIONGZTUDZQLAHDTKLNKT~HZ~ZLZSZECZZEZSAGZKQKHKDM1300DZt7~GZr~/eNDai3.ep',QAHanagez'a~t.>BarberRf.ch,3lmai~~t(5LY~gerLauzieDic3csan,Car~~icamcnMgiee='Z~Hi11iams;,QA,Technican1.33l&R28'9714:534I25374968PAGE.83 0

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