铝合金铸棒缺陷的产生原因Causes of defects in Aluminum Alloy Casting Bars.docx
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铝合金铸棒缺陷的产生原因Causes of defects in Aluminum Alloy Casting Bars.docx
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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)
Classificationofdefectsinaluminiumandaluminiumalloyingots
Name,fataldefect,seriousdefect,generaldefect,minordefect
Thechemicalcompositiondoesnotagreewith*
Tissueburn*
Slaginclusion**
Porosityandporosity***
Crack*
Sizediscrepancy***
Metalcompound*
Laminated*
Brightgrain*
Coarsegrains**
Name
Leukoplakia*
Bending*
Whitedot*
1.thechemicalcompositiondoesnotagreewitheachother
Wheretherangeofchemicalcompositionofaluminumandaluminumalloyexceedsthenationalstandard
(GB/T3190-1996)providesthatimpuritieshigherthantheceiling,andaffectthefinalperformanceofsubstandardproducts,arecalledchemicalcompositiondoesnotmatch,isanabsolutewaste.
Causes
1-thechemicalcompositionoftheingotinthefactorydoesnotmeetthetechnicalrequirementsorhasnotechnicalqualificationcertificate.
Theestimatedpercentageofwasteandmixtureweightin2-blendingisinaccurate.
The3-ingredientaccuratelymatchesthealloyingelementsofthealloy.
Thecompositionof4-intermediatealloyisnotqualifiedorfluctuatesgreatly.
5-rapidanalysisofspecimenswithoutrepresentation,laboratory,erroranalysis,orerroranalysisreport.
6-alloytransfergroupdoesnotwashfurnaceorwashingfurnaceisnotthorough.
Whenthe7-issmelted,theburningistoolargeortheamountofburninglossisnotaccurate.
8-metalmeltinthefurnaceforalongtimeandburning,mixingcomponentsunevensampling.
2.layereddefects:
Intheprocessofcastingliquidmetalmelt,openmoldhasbeensolidifiedonthesurfacenearthemoldwall,theingotsurfaceformedonthetwolayer,calledalayer(orcoldisolation).
Thisdefectseriouslydamagedthecontinuityofthewholeingotstructure,andshouldgenerallybewasteproducts.Ifthecarcanbeallowedtousecompletelydisappear.
Formingreason:
1-castingspeedisslow,themetalmeltflowisinsufficient,theedgeiseasytosolidify,themeltthatcontinuestosupplydoesnotadduptosolidifyaheadoftime;
Thecastingtemperatureof2-islow,thefluidityofmoltenmetalisnotgood,anditiseasytosolidifynearthemouldwall;
Thecastingfunnelof3-isnotplacedproperly,andthemetalmeltflowsunevenlyintothefunnel;
4-thefunnelisblocked,thecoolinginthecondensatetankisuneven,andthemetalisquicklysolidifiedintheplacewherethecoolingrateisgreat;
5-lubricationunevenorpartialoilingtoomuch;
6-castingstopshalfway,suspensionormetalmeltflow,highandlow;
Thetaperinthe7-condensertankdoesnotmeettherequirements.
3.crackandstretchmark
Asthefrictionbetweentheoutersurfaceoftheingotandthemouldexceedsthestrengthoftheingotitself,atensilemarkisformedonthesurfaceoftheingot,andtheingotisbrokenorbrokeninseverecases.
Thiskindofdefectseriouslydamagedthecontinuityofthewholeingotstructure,andshouldbewasteinseriouscondition.Ifthecarcanbeallowedtousecompletelydisappear.
Formingreason:
1-moldinternalsurfaceisnotsmooth,burr,scratches,lubricationisnotgood;
The2-mouldisproducedbytiltingandcausinggreatresistancewhentheingotislowered;
Intheprocessof3-casting,themetalbodyishighandlowandcausessuspensionofthecore(hollowingot)oraluminumleakage;
4-castingspeed,castingtemperatureishigh,castingwaterpressureisbig,easytocausecrackorstretchmark
4.slaginclusion
Metalslagiscustomarilyreferredtoascopper,ironandothermetalfragmentsthatoccasionallyfallintopieces;
Thenon-metallicslaginclusionmainlyreferstotheslaginclusiononthelowtestpiece,suchasslaginclusion,slagandflux,asbestosplateandsoon.
Slaginclusionisdividedintosurfaceslaginclusionandinternalslaginclusion.
Slaginclusiondamagesthecontinuityofingotstructureandseriouslyaffectsthequalityoftheproducts.
Causes:
1-rawandauxiliarymaterialsarenotclean,suchasoil,dirt,dust,moistureandsoon;
Intheprocessof2-smelting,thesurfaceoxidefilmhasbeendestroyedmanytimesbecauseofrepeatedfeeding,dilutionandagitation;
Intheprocessofconvertingto3-impacttoomuch,notfullofmoltenmetalfloworgapistoolargeduetooxidationslag;
4-refiningimproperoperation,refiningisnotsufficient,sothattherefiningeffectisnotgood;
5-inthecastingprocess,themetallevelfluctuatesgreatly,eachfallsnearlytosealoff,andthebeginningandendingareimproper;
6-isaffectedbythenatureofalloy.Ifsomealloysarepoorinfluidity,itisdifficulttofloatslag;
7-castingtemperatureistoolow,slagisdifficulttofloat
5.oxidefilm
FragmentsofcomplexoxidesconsistingofmetalaluminumandAI2O3inoxidationinairandotheroxidesinalloyelements(suchasMgO)existintheingotandformanoxidefilmintheingot.
Itdestroysthecontinuityandcompactnessoftheinternalstructureofthealloyandreducesthevariouspropertiesofthealloy.
Causes:
1-rawandauxiliarymaterialsarenotclean:
ifthereisoil,moisture,moisture,corrosion,dust,sedimentandsoon;
Intheprocessof2-smelting,repeatedfeeding,dilutingandmixingmethodsareimproper,whichdestroythesurfaceoxidefilmandbecomefragmentsandfallintothemelt.
3-humidityseason,easytoproduceoxidationfilm;
Intheprocessofconverting4-meltmetalmeltwithoutfullpipeflow,theimpactistoolargeorthefallwasnotclosedduetooxidemeltintopieces.
5-melttemperatureislow,thetimeofslagremovalanddegassingisshort,andthecastingtimeisnotenoughinthestaticfurnace;
Thevarioustoolsusedby6-arenotgoodforpreheatinganddrying;
Thecastingtemperatureof7-isonthelowside,andtheoxidefilmishardtofloat;
Inthe8-castingprocess,themetallevelfluctuatesgreatly,andthebeginningandendingoperationsareimproper.
6.cracks
Theinternalcausesofcrackformationcanbedividedintotwocategories:
hotcrackandcoldcrack.
Accordingtotheshapeofcrackintheingotsandpartscanbedividedintocenter(tongxinfang)crack,surfacecrack(subcutaneous),radialcrack,cycliccrack,transversecracks,crack,crackatthebottomofthegate,thecrackforproofreadingwaste.
Causes:
1-adjustthemainchemicalcompositionreasonably,strictlycontrolharmfulimpuritycontentand"mutualrelation"";
2-improvesthepurityofmoltenmetal,eliminatesgasandslagcompletely,andpreventsthemetalmeltfromoverheatingatthesametime;
3-allkindsofcastingtoolsaresuitableforuse.Theyarefirmandsmooth,withgoodsurfacefinish;
4-reasonablyadjustthemanufacturingspeed,castingtemperature,coolingstrengthandtheirrelationship;
5-crackalloy,largesizeingotcasting,beginningwithpurealuminumorthebasictechnologiesofbedding.
7.porosityandporosity
Themoltenmetalcontainsalargeamountofgas,andtheinnersurfaceoftheingotisformedwitharoundcavitycalledablowhole.
Atthegrainboundaryandthedendritenetwork,macroscopicormicroscopicporosityisformed,whichiscalledporosity.
Thisdefectdamagestrongbindingingotbetweengrains,themicrostructureiscompact,intheprocessofwelding(ifnotmoredifficult,whilestomatal)severelydegradesthemechanicalpropertiesoftheproducts.Suchdefectsarenotallowedtoexist.
Causes:
1-alloy,whensomealloysarecast,startthesolidificationtemperatureandtheendofthesolidificationtemperaturedifference,thatis,thetransitionbeltsizeislarge,sothatthecontractionandgasescapedifficult;
2-metalmelthaslongresidencetime,poorcoverageorlocaloverheating,whichcausesalargeamountofgastobeabsorbedbymelt;
3-furnace,tools,nitrogenandchlorinecontentishigh,refininggasisnotcomplete;
4-haslowcastingtemperature,fastcastingspeedandlittlecoolingstrength,soitisdifficulttoescapegasinthemelt;
5-hightemperatureandhighhumidityseason,theairhumidityislarge,themetalmeltsuctionvolumeincreased.
8.:
whiteedgeAluminumAlloybottom,andthecrosssectionofthegate,thereisawhitespotdefect,scattered,cottony,knownaswhitespots(alsocalledwhite).
Thiskindofdefectismostlikelytooccurinhighmagnesiumalloys,anditgreatlyreducestheelongationofalloys.
Causes:
1-whitereasonsandrelatedtothecomposition(includingmagnesiumalloy)suchasLF2,LF3,LF6,LY12,LC4,LD5alloylargesizeingot.
2-rawmaterialishumid,themelthashighgascontent,andthegasisnotcompletelyeliminatedduringrefining.
Theresidencetimeof3-meltislong,thecoatingispoor,andtheintakeofmetalmeltisincreasing.
4-moldishighandhaslittlecoolingstrength.
5-castingspeedistooslow,coolingwatertemperatureistoohigh.
9.whitespot
Thewhitespotisintheinitialstageofcasting,becausetheliquidflowimpulse,thesuspensionofpurealuminuminaluminumliquidcrystalbedfullcondensationinthecastingfunnelbottom,andgraduallygrowup,graduallyintoasmallnumberofelementswhensubjectedtosomeexternalforcevibrationorerosionandcolonyformationinwhitecast.
Theappearanceofthewhitespotreducesthemechanicalstrengthoftheproductandcannotbewellpressedaftertheprocessingdeformation,soitisnotallowedtoexist.
Causes:
1-castingbeginswhenthebeddingoperationmustbecarefully,topreventthesuspensionofpurealuminuminthefunnelbottomorthemoldwall,don'tshakeafterthestartofcastingprocessandfunnel.
2-bedtemperatureandimprovethealuminum,hitinbedbeforethescum.
3-fun
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