制造工程與技術專業(yè)英語閱讀(一)教案

張新房專張新房專業(yè)英語閱讀（一）教案PartII:Metal-CastingProcessesandEquipment金屬鑄造工藝與設備Inthispart,someimportantandfundamentalknowledgeaboutcastingmustbeunderstood.Forthischapter,weshouldknowthedifferencesofChinesemeaningsfortheseprofessionalEnglishwords,andIwilladdresstheseimportantparts.Forming:成型Molding:造型Powdermetallurgy:粉末冶金Pouring:澆注Ornament:裝飾物Intricate:復雜的Hollow:中空的Fig.II.1Castpartsinatypicalautomobile圖2.1一個典型的汽車中的鑄造部件Waterpump:水泵Pulley:滑輪Grill:柵欄Intakeandexhaustmanifold:進氣和排氣管Diskbrake:剎車片SandSSandShellExpandablepatternPlasterCeramicInvestmentMetalcastingprocessesFoundriesExpandablemoldPermanentmoldSlushPressureDieCentrifugalSqueezeSemisolidSinglecrystalformicroelectronicsSingle-crystalturbinebladesDirectionalsolidificationCompositemoldSingle-crystalgrowingBrakecylinder:閘缸Lettering:編字碼Differentialhousing:差速機殼Transmissionhousing:變速機殼Engineblock:汽缸體Carburetor:化油器Piston:陽模Alternatorhousing:同步發(fā)電機殼Fig.II.2.Outlineofmetal-castingprocessesdescribedinpartII.金屬鑄造工藝鑄造金屬鑄造工藝鑄造沙殼體消耗性的圖形高聚物陶瓷圍模料消耗性模永久性模凝殼壓力鍛壓離心擠壓半凝固單晶生長用于微電子的單晶單晶葉片定向凝固復合模具Chapter10FundamentalsofMetal-Casting金屬鑄造基礎Forthischapter,itwasdividedintotheseparts:Introduction:簡介Solidificationofmetals:金屬的凝固Fluidflow:流體流動Fluidityofmoltenmetal:熔融金屬的流動性Heattransfer:熱傳遞Defects:缺陷First,1.IntroductionThecastingprocessbasicallyinvolvesthreesteps:pouringmoltenmetalintoamoldpatternedaftertheparttobemanufactured;(把熔融金屬澆注到加工好的模具型腔)allowingittocoolandsolidify（冷卻和凝固）removingthemetalfromthemold（從模具中取出金屬）Asweknow,thecastingistheoldestprocesstomanufacturepartoftoolinthehumanbeing’shistory,becauseithasmanyadvantagescomparedwithothermanufacturedprocessesasfollows:complexshapes,suchasdifferentialhousing(差速機殼)usedintheautomobile,crankshaft（曲軸）andsoon;Verylargepart,suchasenginehousingusedintheshipmaking.Utilizetheworkpiecesthatothermanufacturedprocessescannotproduceofuneconomic,suchasturbineblade(渦輪機葉片).So,itisessentialforustounderstandthefundamentalsofmetalcastingbystudyingthisbookhard.Therearesomeimportantconsiderationsinthecastingoperationasfollows:Theflowofthemoltenmetalintothemoldcavity:熔融金屬流入模具型腔,Fluidity.Thecoolingandsolidificationofmetalinthemold:金屬在模具中的冷卻和凝固:heattransfer:熱傳導.Theinfluenceofdifferenttypeofmoldmaterials,differentheattransferringability,不同的模具材料具有不同的熱傳導能力.Inthispart,wetalkedaboutsomeintroductionsofmetalcasting;inthenext,wewilltalkthesecondpart:solidificationofmetals.2.SolidificationofmetalsAsweknow,fordifferentmetals,suchaspuremetalsandalloys,thesolidificationprocessesaredifferent,sotheywillbedividedintopuremetalandalloytobediscusseddifferentsolidificationprocesses.1,PuremetalsForpuremetal,themeltingpointisconstant,so,thesolidificationislikethisone:ReleaseoflatentheatoffusionReleaseoflatentheatoffusion熔化潛熱AfterreachingmeltingpointsolidificationfrominterfaceandthentocenterwithdifferentgraintypeandsizeFig.10.1Schematicillustrationofthreecasterstructureofmetalssolidifiedinasquaremold;a,puremetals;b,solid-solutionalloys;c,structuredobtainedbyusingnucleatingagents(孕育劑).Chillzone:極冷區(qū)，白口區(qū)，grainsizeduetoveryhighcoolingrate.Fig.10.1Schematicillustrationofthreecasterstructureofmetalssolidifiedinasquaremold;a,puremetals;b,solid-solutionalloys;c,structuredobtainedbyusingnucleatingagents(孕育劑).Columnarzone:柱狀區(qū)，largegrainsizeduetolowercoolingrateandheterogeneousnucleation.Equiaxedzone:等軸晶區(qū)，homogeneousnucleation.Fig.10.2.Developmentofapreferredtexture(擇優(yōu)質(zhì)構)atacoolmoldwall.Notethatonlyfavorablyorientedgrainsgrowawayfromthesurfaceofthemold.Fig.10.3.Schematicillustrationofalloysolidificationandtemperaturedistributioninthesolidifyingmetal.NFig.10.3.Schematicillustrationofalloysolidificationandtemperaturedistributioninthesolidifyingmetal.Notetheformationofdendritesinthemushyzone(多空隙的區(qū)域).10.2.2alloysThesolidificationprocessofalloyscanbeschematicallyillustratedfromFig.10.3.Fromthisfigure,wecansee,thesolidificationtakesplaceinatemperaturerange,TlandTs.Thesolidificationprocessofthistypealloycanbeillustratedasfollow:ChillzoneformationBelowTlBetweenChillzoneformationBelowTlBetweenTlandTsBelowTsCompleteDendriteformationSolidificationbeginCompleteDendriteformationSolidificationbeginForthistypedendrite,itcanbenamedascolumnardendrite,withthree-dimensionalarmsandbranches.Thestructureofdendriteinfluencesthepropertiesofcastingseriously,soitisessentialtofindandstudytheeffectorsonitsstructure.Asmentionedabove,thestructureofdendriteisaffectedbythemushyzone;inotherword,itcanbedescribedasdifferentmushyzoneduringsolidification,andthemushyzonecanbenamedasfreezingrange,asthis:Fig.10.4(a)Solidificationpatternsforgraycastironina180mmsquarecasting.Notethatafter11min.ofcooling,dendritesreacheachother,butthecastingisstillmushythroughout.(b)Solidificationofcarbonsteelinsandandchill(metal)molds.NotethedifferenceinsolidificationpatternsasthecarboncontentincreasesFreezingrange=Tl-Ts,thetemperaturedifferencebetweenTlandTsduringsolidification.Forexample:forpuremetalsandeutecticalloys,freezingrange=0,so,nomushyzone,nodendriteformation.Usually,theshortfreezingrange<50oC,forexample,Fe-basealloys.Thelongrangefreezingrang>110oC,example,AlandMg-basealloys,andthesealloysareinamushystatethroughoutmostofsolidificationprocess.EffectofcoolingrateThecastingstructureisaffectedseriouslybythecoolingrate:Usually,forslowcoolingrate(<102K/s),coarsedendriteformation;Fastercoolingrate(ontheorderof104K/s),finerdendriteformation;Highercoolingrate(106~108K/s),amorphousformation.Ascoolingrateincreases,thegrainsizedecreases,sostrengthandductilityenhanced,thatishall-petchformula.Forthesolidifiedstructure,itcanbecertifiedbytheratioofG/R,whereGisthermalgradientattheinterfaceofliquidandsolid,andRistherateatwhichtheliquid-solidinterfacemoves.TypicalvaluesforGrangefrom102to103K/mandforRfrom10-3to10-4m/s.Dendritictypestructures(Figs.5.5aandb)typicallyhaveanratiointherangeof105to107,whereasratiosof1010to1012Fig.10.6.Schematicofcaststructuresin(a)planefront,singlephase,and(b)planefront,twophases.Fig.10.5.Schematicillustrationofthreebasictypesofcaststructures:(a)columnardendritic;(b)equaiaxeddendritic;and(c)equiaxednondendritic.Fig.10.6.Schematicofcaststructuresin(a)planefront,singlephase,and(b)planefront,twophases.10.2.3.structure-propertyrelationshipAllcastingsarehopedtomeetdesignandservicerequirements.Usually,thepropertyisuptostructure.Thecompositionsofdendritesandtheliquidmetalaregivenbythephasediagramsofparticularalloys,usuallybinaryalloys.Ascoolingrateverylow,dendritewithuniformcompositiondevelops.Normal(fast)coolingrate,coredendritesdevelopwithdifferentcompositionatsurfaceandcenter,knownasconcentrationgradient(濃度梯度):highercontentofalloyingelementinthesurfacelayerthanthatofcenter.Thatisduetosoluterejectionduringsolidifiedprocess,resultinginmicrosegregation(微觀偏析).Macrosegregation(宏觀偏析)involvesdifferencesincompositionthroughoutthecasting.Normalsegregation(正常偏析),versesegeration(反向偏析),thereasonisthatliquidmetal(havingahigherconcentrationofalloyingelements)entersthecavitiesdevelopedfromsolidificationshrinkage(收縮)inthedendriticarmswhichsolidifiedsooner.Gravitysegregation(重力偏析)describestheprocesswherebyhigher-densityinclusions(夾雜)orcompositionssink(下沉)andlighterelements(suchasantimonyinantimony-leadalloy(銻-鉛))float(上浮)tosurface.Inoculants(孕育劑)inducethenucleationofthegrainsthroughouttheliquidinducedheterogeneousnucleation.Convectionpromotestheformationofanouterchillzone,refinesgrainsizeandacceleratesthetransitionfromcolumnartoequiaxedgrains.Dendritemultiplication:枝晶增殖,rheocasting:流變鑄造Inthispart,wetalkedaboutthesolidificationprocessfordifferentmetalsandtheproperty-structurerelation;next,thefluidflowwillbetalked.10.3.FluidflowThefluidflowismostimportantfactorincasting.Asshowninfig.10.7,thecastingprocessisdescribedas:themoltenmetalispouredthroughapouringbasin(轉包，澆注槽)orcup.Itthenflowsthroughthegatingsystem(澆注系統(tǒng))(sprue,runnersandgates,注流口,流道,內(nèi)澆道)intothemoldcavity.Sprueisaverticalchannelthroughwhichmoltenmetalflowsdownwardinthemold.Runnersarethechannelsthatcarrythemoltenmetalfromthespruetothemoldcavity,orconnectthespruetothegate.Thegateisthatportionoftherunnerthroughwhichthemoltenmetalentersthemoldcavity.Risers(冒口)serveasreservoirs(儲液槽)tosupplythemoltenmetalnecessarytopreventshrinkageduringsolidification,asshowninFig.10.7.Fig.10.7.Schematicillustrationofatypicalriser-gatedcasting.Risersserveasreservoirs,supplyingmoltenmetaltothecastingasitshrinksduringsolidification.Trapcontaminant:捕獲雜質(zhì),prematurecooling:過早冷卻,gasentrapment:夾氣Fig.10.7.Schematicillustrationofatypicalriser-gatedcasting.Risersserveasreservoirs,supplyingmoltenmetaltothecastingasitshrinksduringsolidification.Gatingsystemdesignisthemostimportantparttogethighqualitycastings.Twobasicprinciplesoffluidflowarerelevanttogatingdesign:Bernoulli`stheoremandlawofmasscontinuity.Bernoulli`stheorem:百努利定律10.2Where:h:theelevationaboveacertainplane,p:pressureatthatelevation,v:velocityoftheliquidatatelevation,ρ:thedensityofthefluid,g:gravitationalconstant.Conservationofenergyrequiresthat,ataparticularlocation,inthissystem,therelationshipissatisfied:10.3Where,subscripts(下標)1and2representtwodifferentelevations,andfrepresentsthefrictionallossintheliquidasittravelsdownwardthroughthesystem.Continuity(連續(xù)性)Thelawofmasscontinuity(質(zhì)量連續(xù)性)statesthatforincompressible(不可壓縮的)liquidandinasystemwithimpermeable(不可滲透的)wall,therateofflowisconstant:10.4WhereQ:therateofflow,A:thecross-sectionalareaoftheliquid,andv:theaveragevelocityoftheliquidinthatcross-sectionallocation.Thedescription1and2refertotwodifferentlocationsinthesystem.Forexample,forspruedesign:10.5so,theareaofthebottominthesprueissmallerthanthatoftop,thatmeanstaperedsprue(圓錐型鑄道).Aspiration:吸出,choke:節(jié)流口，縮頸Recallthatinafree-fallingliquid(suchaswaterfromafaucet:水龍頭)thecross-sectionareaofthestreamdecreasesasitgainsvelocitydownward.Ifwedesignaspruewithaconstantcross-sectionareaandpourthemoltenmetalintoit,regionsmaydevelopwheretheliquidlosscontactwiththespruewalls.Asaresultaspiration,aprocesswherebyairissuckedinorentrappedintheliquid,maytakeplace.Ontheotherhand,taperedspruesarenowreplacedinmanysystemsbystraight-sidedsprureswithachoketoallowthemetaltoflowsmoothly.回想自由落下的水流(例如從水龍頭流下的水)，其橫截面積隨其獲得的向下的速度而減小。如果我們設計一個截面積不變的直澆道并向其澆注金屬液，可能會出現(xiàn)液流接觸不到澆道壁的區(qū)域。由于有吸氣作用，在澆注過程中可能卷入空氣。另一方面，錐形的直澆道現(xiàn)在在許多系統(tǒng)中被帶節(jié)流口的平直直澆道所取代，以使金屬液平穩(wěn)地流動。Flowcharacteristics:Animportantconsiderationinthefluidflowingatingsystemsisthepresenceofturbulence(湍流)asopposedtothelaminarflow(層流).WeusetheReynoldsnumber(雷諾系數(shù)),Re,toquantify(定量)thisaspect(方面)offluidflow;Itrepresentstherationtheinertia(慣性)totheviscousforces(粘滯力)influidflow,andisdefinedas:10.6Where,v:velocity,D:diameterofthechannel;ρandηdensityandviscosity(粘度).Re<2000,laminarflow,good;2000~20000,mixtureoflaminarandturbulentflow,butnoharmless.>200000,severeturbulentflow,resultinginairentrainmentandtheformationdross(熔渣)(thescum(浮渣)thatformsonthesurfaceofthemoltenmetal)fromthereactionoftheliquidmetalwithairandothergases.Techniquesforminimizingturbulencegenerallyinvolveavoidanceofsuddenchangesinflowdirectionandinthegeometryofchannelcross-sectionsingatingsystemdesign.Mitigate:緩和，減小Skimming:擋渣10.4FluidityofmoltenmetalThecapability(能力，本領)ofthemoltenmetaltofillmoldcavitiesiscalledfluidity(流動性);itconsists(包括)oftwobasicfactors:(1)characteristicsofthemoltenmetal,and(2)castingparameters.Thefollowingcharacteristicsofmoltenmetalinfluencefluidity:a,viscosityincreasing,fluiditydecreasing;b,surfacetension(表面張力)increasing,fluiditydecreasing;c,inclusion(夾雜)increasing,fluiditydecreasing;d,solidificationpatternofthealloy,freezingrangeincreasing,fluiditydecreasing.Thefollowingcastingparametersinfluencefluidityandalsoinfluencethefluidflowandthermalcharacteristicsofthesystem:Molddesign,thedesignanddimensionsofsprue,runnerandrisersallinfluencefluidity;Moldmaterialsanditssurfacecharacteristics:thermalconductivityandsurfaceroughincreasing,fluiditydecreasing;Degreeofsuperheat(過熱)increasing,fluidityincreasing;Rateofpouringdecreasing,fluiditydecreasing;Heattransfer.Thisfactordirectlyaffectstheviscosityoftheliquidmetal.Castabilty(可鑄性):theeasewithwhichametalcanbecasttoobtainapartwithgoodquality,includesnotonlyfluiditybutalsocastingparametersaswell.Fig.10.8Atestmethodforfluidityusingaspiralmold(螺旋模).Fig.10.8Atestmethodforfluidityusingaspiralmold(螺旋模).Thefluidityindex(流動性指數(shù))isthelengthofthesolidifiedmetalinthespiralpassage(通道，通路).Thegreaterthelengthofthesolidifiedmetal,thegreaterisitsfluidity.10.5HeattransferAnimportantconsiderationincastingistheheattransferduringthecompletecyclefrompouringtosolidificationandcoolingtoroomtemperature.Forinstance,incastingthinsections,themetalflowratesmustbehighenoughtoavoidpremature(早期的)chillingandsolidification.However,theflowratemustnotbesohighastocauseexcessive(過多的)turbulencewithitsdetrimental(有害的)effectsonthecastingprocess.Fig.10.9Temperaturedistributionattheinterfaceofthemoldwallandtheliquidmetalduringsolidificationofmetalsincasting.Theshapeofthecurvedependsonthethermalpropertiesofthemoltenmetalandthemold.Fig.10.9Temperaturedistributionattheinterfaceofthemoldwallandtheliquidmetalduringsolidificationofmetalsincasting.10.5.1.SolidificationtimeDuringearlystagesofsolidification,athin,solidifiedskinbeginstoformatthecoolmoldwallsand,astimepasses,theskinthickens.Withflatmoldwall,thisthicknessisproportionaltothesquarerootoftime.Thesolidificationtimeisafunctionofthevolumeofacastinganditssurfacearea(Chvorinov’srule);thatis,Solidificationtime=10.7Where,C:aconstantthatreflectsmoldmaterial,metalproperties(includelatentheat),andtemperature.Thatmeans,thesolidificationtimeisinverseproportionaltospecificarea.Notethattheskinthicknessincreaseswithelapsedtime,butthattheskinisthinneratinternalangel(內(nèi)切角)thanatexternalangels(外切角).Thislatterconditioniscausedbyslowercoolingatinternalangelsthanatexternalangels.Fig.10.10SolidifiedskinonasteelcastingForexample,samevolumeforsphere,cubeandcylinder,thesequenceofsurfaceareais:sphere<cylinder<cube,sospherehasfastestsolidificationrate.Fig.10.10Solidifiedskinonasteelcasting10.5.2.Shrinkage(收縮)Shrinkageistheresultofthefollowingthreeevents:contraction(收縮)ofthemoltenmetalasitcoolspriortoitssolidification;contractionofthemetalduringphasechangefromliquidtosolid(latentheatoffusion);Contractionofthesolidifiedmetal(thecasting)asitstemperaturedropstoambienttemperature.TABLE10.1SolidificationContractionforvariousCastMetalsMetaloralloyVolumetricsolidificationcontraction(%)MetaloralloyVolumetricsolidificationcontraction(%)Aluminum6.670%Cu-30%Zn4.5Al-4.5%Cu6.390%Cu-10%Al4Al-12%Si3.8GrayironExpansionto2.5Carbonsteel2.5~3Magnesium4.21%carbonsteel4Whiteiron4~5.5copper4.9zinc6.5Thelargestamountofshrinkageoccursduringcoolingofthecasting.Notethatgraycastironexpands,duetothatgraphitehasarelativelyhighspecificvolume,andwhenitprecipitatesasgraphiteflakes(薄片，片狀的)duringsolidification,itcausesanetexpansionofthemetal.10.6DefectsSevenbasiccategoriesofcastingdefectsnamedbytheInternationalcommitteeofFoundryTechnicalAssociationsareshownasfollows:Metallicprojection(突出，隆起),consistingoffins(毛刺),flash(飛刺),ormassiveprojectionsasswells(隆起)androughsurface(粗燥表面，鑄疵);Cavities(空洞，凹起),consistingofrounded(滾圓的)orrough(粗燥的)orexposed(外露的)cavities,includingblow-holes(砂眼),pinholes(引孔線,針孔，氣孔),andshrinkagecavities(收縮孔),hottear(熱撕裂),exothermicpadding(發(fā)熱貼片).Discontinuities(不連續(xù)性，間斷),suchascracks,coldorhottearing,andcoldshuts(冷疤);Defectivesurface,suchassurfacefolds(表面褶皺),laps(褶皮),scars(凍結物),adheringsandlayers,andoxidescale(氧化皮);Incompletecasting,suchasmisruns(鑄件不滿),insufficientvolumeofthemetalpouredandrunout,reason:moltenmetalwithlowtemperatureorlowspeedofpour;Incorrectdimensionsorshape,owingtofactorssuchasimpropershrinkageallowance,patternmountingerror,irregularcontraction,definedpattern,orwarpedcasting(翅曲，凹凸);Inclusion(夾雜),whichformduringmelting,solidificationandmolding,spalling(漲裂，剝落).Fig.10.11Examplesofhottears.Thesedefectsoccurbecausethecastingcannotshrinkfreelyduringcooling,owingtoconstraintsinvariousportionsofthemoldsandcores.Exothermic(heatproduction)compoundsmaybeused(asexothermicpadding)tocontrolcoolingatcriticalsectiontoavoidhottearing.Fig.10.12Examplesofcommondefectsincastings.Thesedefectscanbeminimizedoreliminatedbyproperdesignandpreparationofmoldsandcontrolofpouringprocedures.Fig.10.12Examplesofcommondefectsincastings.Thesedefectscanbeminimizedoreliminatedbyproperdesignandpreparationofmoldsandcontrolofpouringprocedures.Fig.10.13Varioustypesof(a)internaland(b)externalchills,usedincastingstoeliminateporositycausedbyshrinkage.Chillsareplacedinregionswherethereisalargervolumeofmetal,asshownin(c).10.6.1Fig.10.13Varioustypesof(a)internaland(b)externalchills,usedincastingstoeliminateporositycausedbyshrinkage.Chillsareplacedinregionswherethereisalargervolumeofmetal,asshownin(c).Porosityinacastingmaybecausedbyshrinkageorgasesorboth,itdeducesthestrengthandductilityofthecastingorevenfailed.Porositycausedbyshrinkagecanbereducedoreliminatedbyvariousmeans.Adequateliquidmetalshouldbeprovidedtoavoidcavitiescausedbyshrinkage.Internalorexternalchills(冷鐵，冷模,冷卻片),arealsoeffectivemeanstoreduceshrinkageporosity.Thefunctionofchillsistoincreasetherateofsolidificationincriticalregions.Fig.10.14Solubilityofhydrogen(H)inaluminum(Al).Notethesharpdecreaseinsolubilityasthemoltenmetalbeginstosolidify.Liquidmetalshavemuchgreatersolubility(溶解度)forgasesthandosolidmetals,asshowninFig.10.14.Whenametalbeginstosolidify,thedissolved(溶入的)gasesareexpelled(擠出)fromthesolution.Gasesmayalsoresultfromreactionsofthemoltenmetalwiththemoldmaterials.Gaseseitheraccumulate(聚集)inregionsofexistingporosity(suchasininterdendriticregions)ortheycasemicroporosityinthecasting,particularlyincastiron,AlandCu.Fig.10.14Solubilityofhydrogen(H)inaluminum(Al).Notethesharpdecreaseinsolubilityasthemoltenmetalbeginstosolidify.Dissolvedgasesmayberemovedfromthemoltenmetalbyflushing(吹)orpurging(吹洗)withaninertgas(惰性氣體),orbymeltingandpouringthemetalinavacuum.Ifthedissolvedgasisoxygen(O),themoltenmetalcanbedeoxidized(脫氧).SteelisusuallydeoxidizedwithAl,Cu-basedalloyswithphosphoruscopper(磷銅),titanium(Ti),andzirconium-bearingmaterials.Whethermicroposityisaresultofshrinkageoriscausedbygasesmaybedifficulttodetermine.Iftheporosityissphericalandhassmoothwalls,itisgenerallyfromgases.Ifthewallsareroughandangular.Porosityislikelyfromshrinkagebetweendendrites.Gross(粗的、大的)porosity(isfromshrinkageandisusuallycalledshrinkagecavity(收縮孔).SUMMARYCastingisasolidificationprocessinwhichmoltenmetalispouredintoamoldandallowedtocool.Themetalmayflowthroughavarietyofpassages(includingpouringbasins,sprues,risers,andgatingsystem)beforereachingthefinalmoldcavity.Bernoulli’stheorem,thecontinuitylaw,andtheReynoldsnumberaretheanalyticaltoolsusedindesign,withthegoalsofanappropriateflowrateandtheeliminationofdefectsassociatedwithfluidflow.鑄造是一種凝固工藝方法。這種工藝方法是將熔化的金屬澆注到鑄型中并使之冷卻。金屬液可能流經(jīng)各種通道（包括澆口池，直流道，橫流道，冒口和內(nèi)澆口）才達到最終型腔。利用百努利定律，連續(xù)性定理和雷諾系數(shù)作為設計中的分析工具，以達到適當?shù)牧魉倭髁浚蛄黧w流動性不足而引起的缺陷。Solidificationofpuremetalstakesplaceataconstanttemperature;solidificationofalloysoccursoverarangeoftemperature,dependingoncomposition.Phasediagramsareimportanttoolsforidentifyingthesolidificationpointorpointsfortechnologicallyimportantmaterials.純金屬在確定的溫度凝固；依賴其成分，合金的凝固是在一個溫度區(qū)間進行的。相圖示用于取代工藝材料凝固點的重要工具。Compositionandcoolingratesofthemeltaffectthesizeandtheshapeofgrainsanddendritesinthesolidifiedcasting.Solidificationtimeisafunctionofvolumeofacastinganditssurfacearea(Chvorinov’srule).金屬的成分和冷卻速率影響鑄件凝固后的晶粒和枝晶的尺寸和形狀。凝固時間是鑄件體積和表面積的函數(shù)（契維瑞諾夫定則）。Thegrainstructureofcastingscanbecontrolledbyvariousmeanstoobtainthedesiredproperties.Becausemetalscontractduringsolidificationandcooling,cavitiescanforminthecasting.Porositycausedbygasesevolvedduringsolidificationcanbeasignificantproblem,particularlybecauseofitsadverseeffectonthemechanicalpropertiesofthecastings.Variousdefectscandevelopincastingsfromlackofcontrolofmaterialandprocessvariables.可以通過各種方法來對鑄件的晶粒組織進行控制以獲得所期望的性能。由于金屬在凝固和冷卻期間與型腔接觸，所以型腔能夠形成鑄件。凝固期間析出的氣體引起的氣孔施工嚴重的問題，特別是對鑄件的機械性能有負面的影響。由于缺乏對材料和工藝變量的控制，而在鑄件中形成各種缺陷。Althoughmostmetalsshrinkduringsolidification,graycastironandaluminumalloysactuallyexpand.Dimensionalchangesandcracking(hottearing)anddifficultieswhichcanariseduringsolidificationandcooling.Sevenbasiccategoriesofcastingdefectshavebeenidentified.雖然大多數(shù)金屬在凝固期間產(chǎn)生收縮，但灰鑄鐵和一些鋁合金卻發(fā)生膨脹。在凝固和冷卻期間可能發(fā)生尺寸變化和裂紋（熱撕裂）以及其它問題。已鑒別出的鑄件缺陷有7類。Meltingpracticeshaveddirecteffectonthequalityofcasting,asdofoundryoperationssuchaspatternandmoldmaking,pouringofthemelt,removalofcastpartsfrommolds,cleaning,heattreatment,andinspection.熔煉操作對鑄件質(zhì)量有直接的影響，鑄造操作也是這樣，例如模樣和鑄型制作，金屬液澆注，鑄件出型和清理，熱處理，檢驗等環(huán)節(jié)。TRENDS發(fā)展趨勢Argon-oxygendecarburizationanddeoxidation,aswellaselectroslagremelting,ladlemetallurgy,plasmarefining,andcalciumwireinjectionfortheproductionofhigh-qualitysteels,arenowbeingpracticedbymodernfoundries.氬-氧脫碳和還原，以及電渣重熔，澆包冶金，等離子精煉和鈣絲注入等，正在現(xiàn)代鑄造廠用于優(yōu)質(zhì)鋼生產(chǎn)。Investigationofthefollowingisunderway:electromagneticstirringofthemoltenmetalinthemoldandvibrationofthemoldtoobtainsmallerandmoreuniformgrainsizeduringsolidification;counter-gravitypouring;andshroudingthepouringstream.以下調(diào)查正在進行中：凝固期間電磁攪拌鑄型中的金屬液和振動鑄型以獲得小的和更均勻的晶粒；反重力澆注，屏蔽澆注液流。Computer-aideddesignandmanufacturingtechniquesarebeingusedtopredictsolidificationpatterns,preventcastingdefects,andcalculateweights,volumes,anddimensionsforpropermolddesignandeconomicalproduction.為獲得正確的鑄型設計和更經(jīng)濟地生產(chǎn)鑄件，計算機輔助設計和制作技術正被用于預測凝固模式，防止鑄件缺陷，計算重量，體積和尺寸等。Improvementsintheefficiencyoffurnaces,moltenmetalquality,andpurifyingandfilteringtechniquesarebeingmade.正在開發(fā)應用提高熔爐效率和金屬液質(zhì)量，凈化和過濾等技術工藝。Keywords:Forming:成型Molding:造型Powdermetallurgy:粉末冶金Pouring:澆注Ornament:裝飾物Intricate:復雜的Hollow:中空的Waterpump:水泵Pulley:滑輪Grill:柵欄Intakeandexhaustmanifold:進氣和排氣管Diskbrake:剎車片Brakedrum:制動鼓Brakecylinder:閘缸Lettering:編字碼Differentialhousing:差速機殼Transmissionhousing:變速機殼Engineblock:汽缸體Carburetor:化油器Piston:陽模Alternatorhousing:同步發(fā)電機殼Crankshaft:曲軸turbineblade:渦輪機葉片latentheatoffusion:熔化潛熱nucleatingagents:孕育劑Chillzone:極冷區(qū)，白口區(qū)Columnarzone:柱狀區(qū)Equiaxedzone:等軸晶區(qū)preferredtexture:擇優(yōu)質(zhì)構mushyzone:多空隙的區(qū)域concentrationgradient:濃度梯度microsegregation:微觀偏析Macrosegregation:宏觀偏析Normalsegregation:正常偏析versesegeration:反向偏析shrinkage:收縮Gravitysegregation:重力偏析Inclusion:夾雜Inoculants:孕育劑Dendritemultiplication:枝晶增殖rheocasting:流變鑄造pouringbasin:轉包，澆注槽gatingsystem(澆注系統(tǒng))(sprue,runnersandgates,注流口,流道,內(nèi)澆道)Risers:冒口Reservoirs:儲液槽Trapcontaminant:捕獲雜質(zhì),prematurecooling:過早冷卻,gasentrapment:夾氣masscontinuity:質(zhì)量連續(xù)性incompressible:不可壓縮的impermeable:不可滲透的Aspiration:吸出,choke:節(jié)流口，縮頸Turbulence:湍流,laminarflow:層流Inertia:慣性,viscousforce:粘滯力,viscosity:粘度dross(熔渣)(thescum(浮渣)Mitigate:緩和，減小Skimming:擋渣Thecapability(能力，本領)Fluidity:流動性surfacetension:表面張力Castabilty:可鑄性spiralmold:螺旋模fluidityindex:流動性指數(shù)passage:通道，通路premature:早期的excessive:過多的contraction:收縮flake:薄片，片狀的projection(突出，隆起),consistingoffins(毛刺),flash(飛刺),ormassiveprojectionsasswells(隆起)androughsurface(粗燥表面，鑄疵)Cavities(空洞，凹起),consistingofrounded(滾圓的)orrough(粗燥的)orexposed(外露的blow-holes(砂眼),pinholes(引孔線,針孔，氣孔),andshrinkagecavities(收縮孔),hottear(熱撕裂),exothermicpadding(發(fā)熱貼片)Discontinuity:不連續(xù)性，間斷coldshut:冷疤surfacefolds(表面褶皺),laps(褶皮),scars(凍結物),andoxidescale(氧化皮)misrun:鑄件不滿warped:翅曲，凹凸spalling:漲裂，剝落Porosity:氣孔，孔隙Chill:冷鐵，冷模,冷卻片Chapter11Metal-CastingProcesses第11章金屬鑄造工藝11.1Introduction簡介11.2SandCasting砂型鑄造11.3Shell-moldCasting殼型鑄造11.4Expendable-PatternCasting(LostFoam)一次模鑄造（消失泡沫）11.5Plaster-MoldCasting石膏型鑄造11.6Ceramic-MoldCasting陶瓷型鑄造11.7InvestmentCasting熔模鑄造11.8VacuumCasting真空鑄造11.9Permanent-MoldCasting永久型鑄造11.10SlushCasting凝殼鑄造11.11Pressu