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首页 铝合金铸棒缺陷的产生原因(Causes of defects in Aluminum Alloy…

铝合金铸棒缺陷的产生原因(Causes of defects in Aluminum Alloy Casting Bars).doc

铝合金铸棒缺陷的产生原因(Causes of defects …

_小争小吵小任性_
2018-01-31 0人阅读 举报 0 0 暂无简介

简介:本文档为《铝合金铸棒缺陷的产生原因(Causes of defects in Aluminum Alloy Casting Bars)doc》,可适用于社会民生领域

铝合金铸棒缺陷的产生原因(CausesofdefectsinAluminumAlloyCastingBars)铝合金铸棒缺陷的产生原因(CausesofdefectsinAluminumAlloyCastingBars)Thenonmetallicslaginclusionmainlyreferstotheslaginclusiononthelowtestpiece,suchasslaginclusion,slagandflux,asbestosplateandsoonSlaginclusionisdividedintosurfaceslaginclusionandinternalslaginclusionSlaginclusiondamagesthecontinuityofingotstructureandseriouslyaffectsthequalityoftheproductsCauses:rawandauxiliarymaterialsarenotclean,suchasoil,dirt,dust,moistureandsoonIntheprocessofsmelting,thesurfaceoxidefilmhasbeendestroyedmanytimesbecauseofrepeatedfeeding,dilutionandagitationIntheprocessofconvertingtoimpacttoomuch,notfullofmoltenmetalfloworgapistoolargeduetooxidationslagrefiningimproperoperation,refiningisnotsufficient,sothattherefiningeffectisnotgoodinthecastingprocess,themetallevelfluctuatesgreatly,eachfallsnearlytosealoff,andthebeginningandendingareimproperisaffectedbythenatureofalloyIfsomealloysarepoorinfluidity,itisdifficulttofloatslagcastingtemperatureistoolow,slagisdifficulttofloatoxidefilmFragmentsofcomplexoxidesconsistingofmetalaluminumandAIOinoxidationinairandotheroxidesinalloyelements(suchasMgO)existintheingotandformanoxidefilmintheingotItdestroysthecontinuityandcompactnessoftheinternalstructureofthealloyandreducesthevariouspropertiesofthealloyCauses:rawandauxiliarymaterialsarenotclean:ifthereisoil,moisture,moisture,corrosion,dust,sedimentandsoonIntheprocessofsmelting,repeatedfeeding,dilutingandmixingmethodsareimproper,whichdestroythesurfaceoxidefilmandbecomefragmentsandfallintothemelthumidityseason,easytoproduceoxidationfilmIntheprocessofconvertingmeltmetalmeltwithoutfullpipeflow,theimpactistoolargeorthefallwasnotclosedduetooxidemeltintopiecesmelttemperatureislow,thetimeofslagremovalanddegassingisshort,andthecastingtimeisnotenoughinthestaticfurnaceThevarioustoolsusedbyarenotgoodforpreheatinganddryingThecastingtemperatureofisonthelowside,andtheoxidefilmishardtofloatInthecastingprocess,themetallevelfluctuatesgreatly,andthebeginningandendingoperationsareimpropercracksTheinternalcausesofcrackformationcanbedividedintotwocategories:hotcrackandcoldcrackAccordingtotheshapeofcrackintheingotsandpartscanbedividedintocenter(tongxinfang)crack,surfacecrack(subcutaneous),radialcrack,cycliccrack,transversecracks,crack,crackatthebottomofthegate,thecrackforproofreadingwasteCauses:adjustthemainchemicalcompositionreasonably,strictlycontrolharmfulimpuritycontentand"mutualrelation""improvesthepurityofmoltenmetal,eliminatesgasandslagcompletely,andpreventsthemetalmeltfromoverheatingatthesametimeallkindsofcastingtoolsaresuitableforuseTheyarefirmandsmooth,withgoodsurfacefinishreasonablyadjustthemanufacturingspeed,castingtemperature,coolingstrengthandtheirrelationshipcrackalloy,largesizeingotcasting,beginningwithpurealuminumorthebasictechnologiesofbeddingporosityandporosityThemoltenmetalcontainsalargeamountofgas,andtheinnersurfaceoftheingotisformedwitharoundcavitycalledablowholeAtthegrainboundaryandthedendritenetwork,macroscopicormicroscopicporosityisformed,whichiscalledporosityThisdefectdamagestrongbindingingotbetweengrains,themicrostructureiscompact,intheprocessofwelding(ifnotmoredifficult,whilestomatal)severelydegradesthemechanicalpropertiesoftheproductsSuchdefectsarenotallowedtoexistCauses:alloy,whensomealloysarecast,startthesolidificationtemperatureandtheendofthesolidificationtemperaturedifference,thatis,thetransitionbeltsizeislarge,sothatthecontractionandgasescapedifficultmetalmelthaslongresidencetime,poorcoverageorlocaloverheating,whichcausesalargeamountofgastobeabsorbedbymeltfurnace,tools,nitrogenandchlorinecontentishigh,refininggasisnotcompletehaslowcastingtemperature,fastcastingspeedandlittlecoolingstrength,soitisdifficulttoescapegasinthemelthightemperatureandhighhumidityseason,theairhumidity,Increasingintakeofmetalmelt:whiteedgeAluminumAlloybottom,andthecrosssectionofthegate,thereisawhitespotdefect,scattered,cottony,knownaswhitespots(alsocalledwhite)Thiskindofdefectismostlikelytooccurinhighmagnesiumalloys,anditgreatlyreducestheelongationofalloysCauses:whitereasonsandrelatedtothecomposition(includingmagnesiumalloy)suchasLF,LF,LF,LY,LC,LDalloylargesizeingotrawmaterialishumid,themelthashighgascontent,andthegasisnotcompletelyeliminatedduringrefiningTheresidencetimeofmeltislong,thecoatingispoor,andtheintakeofmetalmeltisincreasingmoldishighandhaslittlecoolingstrengthcastingspeedistooslow,coolingwatertemperatureistoohighwhitespotThewhitespotisintheinitialstageofcasting,becausetheliquidflowimpulse,thesuspensionofpurealuminuminaluminumliquidcrystalbedfullcondensationinthecastingfunnelbottom,andgraduallygrowup,graduallyintoasmallnumberofelementswhensubjectedtosomeexternalforcevibrationorerosionandcolonyformationinwhitecastTheappearanceofthewhitespotreducesthemechanicalstrengthoftheproductandcannotbewellpressedaftertheprocessingdeformation,soitisnotallowedtoexistCauses:castingbeginswhenthebeddingoperationmustbecarefully,topreventthesuspensionofpurealuminuminthefunnelbottomorthemoldwall,don'tshakeafterthestartofcastingprocessandfunnelbedtemperatureandimprovethealuminum,hitinbedbeforethescumfunnelshouldbepavedwithpaint,fullypreheatedbrightgrainTheprimarysegregationofpoorsolidmeltsresultsintheformationofbrightgrainsIthasbright,color,uncertainty,andafewtimeslargerthanthesurroundingcrystaltreecrystal,thiscrystalisreferredtoasopticalcrystalBecausebrightgrainscontainalloyelementsareverylow,willseriouslyreducethemechanicalpropertiesoftheproduct,soitisnotallowedtoexistCauses:ThesurfaceofthefunnelusedatthebeginningofthecastingoftheisnotsmoothortheheatconductivityisnotgoodThefunnelistoohighfromthebottomordoesnotpreheatwellWhenthefunnelsinkstoodeep,thesupercooledzoneoftheliquidportionoftheingotexpandstotheentirevolumeoftheliquidcavity,infavoroftheorderinvolumeInthecourseofcasting,thefunnelisshakenforsomereason,andthebottomofthebottomofthehopperfallsintothecrystallinesurfaceandcondensesintotheingotThecastingtemperatureofislowandthespeedisslowThecoolingofingotsurfaceisstrong,andthecrystaliseasytoproduceprimarysegregationofintermetalliccompoundsandmetalliccompoundsTheinclusionofrefractorycomponentsintheingotstructure,thehighmeltingpointintermetalliccompound,andtheprimarysegregationofthemetalcompoundsfoundinLF,LD,LD,LD,LF,LC,LF,LFandotheralloysTheintermetalliccompoundhashighhardnessandbrittleness,andismostlyblocky,acicularandunevenlydistributedinthecrystal,whichseriouslyaffectsthelateralpropertiesoftheproductsCauses:strictlycontrolsthecontentofrefractorycomponentandimpuritycontentinalloycompositionusesalowmeltingpointmasteralloytomeltrefractoryelementsintothemelttoensurethatitisfullydissolvedinthealloyappropriatelyimprovescastingtemperatureandcastingspeedfullypreheatedcastingfunnelandtransfertool,notinaholeintheliquidfunnelplacedtoodeepsegregationtumorThefusibleprecipitatesingotsurfacecondensationiscalledtosegregation,alsocalledsegregationThesegregationwithinthefusibleingredientsandeutecticcompounds,thecompositionisnotuniform,andthesurfaceoftheingottoeliminatethebulge,coldprocessingCauses:castingtemperatureishighandspeedisfastThegapbetweentheingotandmouldofislarge,themouldisbigandthemouldishighmoldinternalsurfaceisnotsmooth,oillubricationisnotgoodThecastingfunnelofisnotplacedproperlyandtheflowdistributionisunevenlowcoolingrateorpartialwatershortageinmoldingotdiameterislargefeatherycrystalslaceInacontinuouscastingingot,apatternedstructureisformedSomecallitafanshaped,coneshaped,flaky,radial,feathery,lacystructure,commonlyknownasfeatherycrystalsorlacesFeatherycrystalsareavarietyofcolumnarcrystalsThealloywithfeatherlikealloymaybreakdownalongitstwinwhenrollingandfreeforging,andseriouslyaffectthetechnologicalperformanceandmechanicalpropertiesoftheproductCauses:meltingtemperatureistoohigh,toolong,meltlongresidencetimeinthefurnace,thenonselfcrystalnucleusreducedrefininggasexcessivenucleationmaterialseparation,nonselfcrystalnucleusreducedisrelatedtotheamountofgrainrefiningelements,suchasLCalloyingotsWhenthecontentofTiislessthan,theappearanceoffeatherycrystalscannotbecompletelysuppressedwhenthemetalmeltisinjectedcentrallyandisequaltothecrystalfront,thetangentdirectionflowsintotheliquidcavity,sothatthelocaltemperatureishigh,anditiseasytoproducefeatherlikecrystalwhencastingtemperatureishigh,easytoproducefeatherlikecrystalcoarsegrainsandlargecolumnarcrystalsCoarsegrainsrefertolargeequiaxedgrainsCoarsecolumnarcrystalsrefertolargecolumnarcrystalsThepresenceofcoarsegraindefectsseriouslyreducesthemechanicalpropertiesofalloycasting,andeventuallyaffectsthemechanicalpropertiesoftheproductsCausesofcoarsegrain:Whenthealloyisoverheatedorpartiallyoverheated,thenonspontaneousnucleationisdestroyedandthecrystallinecoredecreasescastingtemperatureishigh,crystallizationspeedissmallImproperadjustmentofcompositionandimpuritiesinalloyCausesofcoarsecolumnargrains:reasonablyadjustalloycompositionandimpuritycontent,forexample,inXXXalloy,Mgcontentisreduced,easytoformcolumnarcrystalThecoolingintensityofislarge,thenucleationtimeisshort,thenucleationisreduced,andcolumnarcrystalsareeasytoformmeltoverheatingoroverheating,thenonnuclearliquatesselfRutilatedQuartzcrystalcore,easyreduction,columnarcrystalgrowthiseasytogrowwithcolumnarcrystalsbecauseofitsunequalconcentrationandunequalflowtheingothasbeenoverheatedWhentheingotishomogenizedduringannealing,thetemperatureistoohigh(beyondtherangespecifiedintheprocess)Whenthealloyingotisburned,themechanicalpropertiesdeteriorate,theelongationandfatiguestrengthdecreaseobviously,whichisabsolutelywasteCauses:didnotperformtheprocesscorrectlyandtheheatingtemperaturewastoohighinstrumentmalfunctionorerrorsoakingDistrictuneventemperatureordischargeisnotpitisnotnormal,badventilationequipment,sothateachsectionoftheuneventemperatureoftenoccurringcastingdefects:Thedefectsinthecastingprocessoftenappearinthemacrostructureoftheextrudedproducts:Brightgrain:pooralloycomponent,poorsolidmelt,primarycrystalTreatmentmethods:purealuminum,LFandLFarenotexaminedOtheralloyextrusionsallowfortwopointsofmm,beyondthetwopoints,treatedbyintermetalliccompoundsIntermetalliccompound:ametalcompoundwitharefractorycomponentandahighmeltingpointTreatmentmethods:allprofilespermitthepresenceofmetalcompoundswithmm,andthestripallowsformmintermetalliccompoundstobetwopointsPorosity,slaginclusionandporosity:therearetinyshrinkageholesorporesintheproduct,whichmakesthecrystallinestructurenotcompact,andsometimesthethreeareproducedTreatmentmethod:toacertainextent,destroythegrainfirmness,isnotallowedtoexistOxidefilm:aluminumoxideisfoundinmetalalloyTreatmentmethod:allowmmoxidepoints(pointsarenotcalculated),exceedthestandard,accordingtothemetalcompoundapproachThechemicalcompositionisoverstandard:thecalculationofingredientsisincorrectorunevenmixingorexcessiveburningduringsmeltingThisdefectisentirelyscrapped

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铝合金铸棒缺陷的产生原因(Causes of defects in Aluminum Alloy Casting Bars)

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