材料加工技术外文文献翻译

材料加工技术材料加工，将工业材料从原材料状态转换为成品或产品的一系列操作。工业材料的定义是用于制造“硬”产品的材料，例如为工业和消费者生产的或多或少耐用的机器和设备，而与一次性“软”产品（例如化学品，食品，药品和服装）相反。手工加工的材料与文明一样古老。机械化始于18世纪的工业革命，并在19世纪初期，主要在英国开发了用于成形，定型和切割的基本机械。从那时起，材料加工的方法，技术和机械种类和数量不断增加。从原材料中提取原材料或从基本化学物质或天然物质生产原材料之后，就可以立即开始将材料转换为零件和产品的制造过程循环。金属原料通常分两步生产。首先，对粗矿石进行处理以提高所需金属的浓度；这称为选矿。典型的选矿过程包括粉碎，焙烧，磁选，浮选和浸出。第二，使用诸如冶炼和合金化之类的附加工艺来生产金属，该金属将被加工成最终组装成产品的零件。就陶瓷材料而言，将天然粘土与各种硅酸盐混合并共混以生产原材料。塑料树脂是通过化学方法以粉末，颗粒，油灰或液体形式生产的。合成橡胶也通过化学技术制造，与天然橡胶一样，以板，片，绉纱和泡沫的形式生产，以制造成品零件。将原材料转换为成品的过程具有两个主要功能中的一个或两个：第一，它们将材料制成所需的形状；第二，将材料制成所需的形状。其次，它们改变或改善了材料的性能。成型和成型过程可分为两种类型：在液态状态下对材料执行的操作和在固态或塑性状态下对材料执行的操作。当涉及金属，玻璃和陶瓷时，液体形式的材料的加工通常称为铸造。当应用于塑料和其他一些非金属材料时，称为模塑。大多数铸造和成型过程涉及四个主要步骤：（1）制作零件的精确图案；（2）用该图案制作模具；（3）将液体引入模具中；（4）从模具中取出硬化的零件模具。有时需要进行精加工。通过施加力或压力将固态的材料制成所需的形状。待处理的材料可以处于相对坚硬且稳定的状态，并且可以是诸如条，片，粒料或粉末的形式，或者可以是软的，塑料的或油灰状的形式。固体材料的形状可以是热的或冷的。固态金属的加工可以分为两个主要阶段：首先，通常通过轧制，锻造或挤压将大锭或方坯形式的原材料热加工成较小的形状和尺寸。其次，通过一个或多个较小规模的热或冷成型工艺将这些形状加工成最终零件和产品。材料形成后，通常会对其进行进一步更改。在材料加工中，“去除”过程是消除一块或一部分材料的部分以获得所需形状的过程。尽管去除工艺适用于大多数类型的材料，但它们最广泛地用于金属材料。可以通过机械或非机械方式从工件上去除材料。有许多金属切割工艺。在几乎所有模具中，机加工都涉及将切削工具压在要成型的材料上。该工具比要切割的材料坚硬，可以去除切屑形式的不需要的材料。因此，加工的要素是切削装置，用于固定和定位工件的装置，通常是润滑剂（或切削油）。有四种基本的非切削去除工艺：（1）在化学铣削中，通过化学溶液在金属上的蚀刻反应去除金属；尽管通常应用于金属，但它也可以用于塑料和玻璃。（2）电化学加工采用相反的金属电镀原理，因为工件不是通过电镀过程堆积的，而是在受控的条件下被消耗掉的。通过电流的作用，（3）放电加工和磨削通过高能火花或放电腐蚀或切割金属，（4）激光加工用来自激光的强光束切割金属或耐火材料。另一个进一步的变化可能是“连接”，即永久地（有时只是临时地）将材料彼此粘合或附着的过程。这里使用的术语包括焊接，钎焊，软焊以及粘合剂和化学键合。在大多数连接过程中，通过施加一种或三种能量（热能，化学能或机械能）来产生两块材料之间的结合。可以使用或可以不使用与被连接材料相同或不同的粘结材料或填充材料。材料的特性可以通过热处理或冷处理，机械操作以及暴露于某些形式的辐射来进一步改变。通常通过改变材料的微观结构来实现性能改变。涉及高于室温的温度的热处理和涉及低于室温的温度的冷处理都包括在此类别中。热处理是其中材料的温度升高或降低以改变原始材料的性能的过程。大多数热处理过程都是基于时间-温度循环，包括三个步骤：加热，保持温度和冷却。尽管某些热处理适用于大多数材料系列，但它们在金属上使用最广泛。Materialprocessingtechnology出处：EncyclopediaBritannicaContributorsGloriaLotMaterialsprocessing,theseriesofoperationsthattransformsindustrialmaterialsfromaraw-materialstateintofinishedpartsorproducts.Industrialmaterialsaredefinedasthoseusedinthemanufactureof“hard”goods,suchasmoreorlessdurablemachinesandequipmentproducedforindustryandconsumers,ascontrastedwithdisposable“soft”goods,suchaschemicals,foodstuffs,pharmaceuticals,andapparel.Materialsprocessingbyhandasoldascivilization;

mechanization

beganwiththe

IndustrialRevolution

ofthe18thcentury,andintheearly19thcenturythebasicmachinesforforming,shaping,andcuttingweredeveloped,principallyinEngland.Sincethen,materials-processingmethods,techniques,andmachineryhavegrowninvarietyandnumber.Thecycleof

manufacturing

processesthatconvertsmaterialsintopartsandproductsstartsimmediatelyaftertherawmaterialsareeitherextractedfrommineralsorproducedfrombasicchemicalsornaturalsubstances.Metallicrawmaterialsareusuallyproducedintwosteps.First,thecrudeoreisprocessedtoincreasethe

concentration

ofthedesiredmetal;thisiscalledbeneficiation.Typicalbeneficiationprocessesincludecrushing,roasting,magneticseparation,

flotation,andleaching.Second,additionalprocessessuchas

smelting

andalloyingareusedtoproducethe

metal

thatistobefabricatedintopartsthatareeventuallyassembledintoaproduct.Inthecaseofceramicmaterials,naturalclayismixedandblendedwithvarioussilicatestoproducetherawmaterial.Plasticresinsareproducedbychemicalmethodsinpowder,pellet,

putty,orliquidform.

Synthetic

rubberisalsomadebychemicaltechniques,beingproduced,asisnaturalrubber,insuchformsasslabs,sheeting,crepe,andfoamforfabricatingintofinishedparts.Theprocessesusedtoconvertrawmaterialsintofinishedproductsperformoneorbothoftwomajorfunctions:first,theyformthematerialintothedesiredshape;second,theyalterorimprovethepropertiesofthematerial.Formingandshapingprocessesmaybeclassifiedintotwobroadtypes—thoseperformedonthematerialina

liquidstate

andthoseperformedonthematerialinasolidor

plastic

condition.Theprocessingofmaterialsinliquidformiscommonlyknownas

casting

whenitinvolvesmetals,

glass,andceramics;itiscalledmoldingwhenappliedtoplasticsandsomeothernonmetallicmaterials.Mostcastingandmoldingprocessesinvolvefourmajorsteps:(1)makinganaccuratepatternofthepart,(2)makinga

mold

fromthepattern,(3)introducingtheliquidintothemold,and(4)removingthehardenedpartfromthemold.Afinishingoperationissometimesneeded.Materialsintheir

solidstate

areformedintodesiredshapesbytheapplicationofaforceorpressure.Thematerialtobeprocessedcanbeinarelativelyhardandstableconditionandinsuchformsasbar,sheet,pellet,orpowder,oritcanbeinasoft,plastic,orputtylikeform.Solidmaterialscanbeshapedeitherhotorcold.Processingofmetalsinthesolidstatecanbedividedintotwomajorstages:first,therawmaterialintheformoflargeingotsorbilletsishot-worked,usuallyby

rolling,

forging,or

extrusion,intosmallershapesandsizes;second,theseshapesareprocessedintofinalpartsandproductsbyoneormoresmallerscalehotorcoldformingprocesses.Afterthematerialisformed,itisusuallyfurtheraltered.Inmaterialsprocessing,a“removal”processisonethateliminatesportionsofapieceorbodyofmaterialtoachieveadesiredshape.AlthoughremovalprocessesareThereareanumberof

metal-cuttingprocesses.Inalmostallofthem,machininginvolvestheforcingofacuttingtoolagainstthematerialtobeshaped.Thetool,whichisharderthanthematerialtobecut,removestheunwantedmaterialintheformofchips.Thus,theelementsofmachiningareacuttingdevice,ameansforholdingandpositioningtheworkpiece,andusuallyalubricant(orcuttingoil).Shear-basedmaterialremovalprocessessignificantlyinfluencethequalityofworkpiecesurfaceandimplicitlythecomponentfunctionalperformance.Anin-situSEMnano-cuttingenabledthestudyofcrystalflowandlatticerotationoccurringbelowthecuttingedgeinapolycrystallineNickelsuperalloy.Whennano-cuttingwithinsinglegrainsadeformednanolayerappearsthatconsistsofacrystallatticerotatedexclusivelywithinthecuttingplanewhichisdelimitedfromthebulkofthegrainbyhighangleboundary(HAB);thedepthofdeformednanolayerincreaseswiththematerialpile-up(nano-chip)causedbythegrainshearing.Uponnano-cuttingmultiplegrains,nano-recrystallisationattheHABoccurs,accompaniedbythebendingofthegrainboundary(GB)inthecuttingdirection,aphenomenonthatalsosignificantlyinfluencesthedeformationbehaviourofthegrainscutafterpassingtheGB.Clarifyingtheseaspectsatthenanoscaleiscrucialforunderstandingtheformationofworkpiecesurfacedamageaftermaterialremovaloperations.Electricaldischargemachining(EDM)isanon-conventionalprocessthatiswidelyusedforhigh-precisionmachining,complexproductshapes,andhighhardnessmaterials.Therearefourbasicnoncuttingremovalprocesses:(1)in

chemicalmillingthemetalisremovedbytheetchingreactionofchemicalsolutionsonthemetal;althoughusuallyappliedtometals,itcanalsobeusedonplasticsandglass,(2)

electrochemicalmachining

usestheprincipleofmetal

plating

inreverse,astheworkpiece,insteadofbeingbuiltupbytheplatingprocess,iseatenawayinacontrolledmannerbytheactionoftheelectricalcurrent,(3)

electrodischargemachining

andgrindingerodesorcutsthemetalbyhigh-energysparksorelectricaldischarges,(4)

lasermachining

cutsmetallicorrefractorymaterialswithanintensebeamoflightfromalaser.Anotherfurtheralterationmaybe

“joining,”theprocessofpermanently,sometimesonlytemporarily,bondingorattachingmaterialstoeachother.Thetermasusedhereincludes

welding,

brazing,

soldering,and

adhesive

and

chemicalbonding.Inmostjoiningprocesses,abondbetweentwopiecesofmaterialisproducedbyapplicationofoneoracombinationofthreekindsofenergy:thermal,chemical,ormechanical.Abondingorfillermaterial,thesameasordifferentfromthematerialsbeingjoined,mayormaynotbeused.Thepropertiesofmaterialscanbefurtheralteredbyhotorcoldtreatments,bymechanicaloperations,andbyexposuretosomeformsofradiation.Thepropertymodificationisusuallybroughtaboutbyachangeinthemicroscopicstructureofthematerial.Bothheat-treating,involvingtemperaturesaboveroomtemperature,andcold-treating,involvingtemperaturesbelowroomtemperature,areincludedinthiscategory.

Thermaltreatment

isaprocessinwhichthetemperatureofthematerialisraisedorloweredtoalterthepropertiesoftheoriginalmaterial.Mosttherm