2.1.2CarbonandAlloySteel

◆CarbonSteel碳鋼Aplain

普通的，樸素的carbonsteelisoneinwhichcarbonistheonlyalloying

合金化element.Theamountofcarboninthesteelcontrolsitshardness,strength,andductility.Thehigherthecarboncontent,theharderthesteel.Carbonsteelsareclassifiedaccordingtothepercentageofcarbontheycontain.Theyarereferredto

涉及；談到

aslow,medium,high,andveryhigh-carbonsteels.ENGLISHINMATERIALSSCIENCEANDENGINEERINGII1

Low-carbonSteels低碳鋼=mildsteelSteelswithcarbonrangeof0.05to0.30percentarecalledlow-carbonsteels.Steelsinthisclass

類別aretough

韌性的，堅韌的,ductile

易延展的,andeasilymachined用機器加工,formed,andwelded.Mostofthemdonotrespondto

對…做出響應anyheattreatingprocessexceptcase

箱，盒

hardening表面淬火.

Medium-carbonSteels中碳鋼Thesesteelshaveacarbonrangefrom0.30to0.45percent.Theyarestrongandhardbutcannotbeworkedorweldedaseasilyaslow-carbonsteels.Becauseoftheirhighercarboncontent,theycanbeheattreated熱處理.ENGLISHINMATERIALSSCIENCEANDENGINEERINGII2.1.2CarbonandAlloySteel2Successfulweldingofthesesteelsoftenrequiresspecialelectrodes

焊條；電極,buteventhengreatercaremustbetakentopreventformationofcracksaroundtheweldarea.

HighandVery-high-carbonSteels高碳鋼和超高碳鋼Steelswithacarbonrangeof0.45to0.75percentareclassifiedashigh-carbonandthosewith0.75to1.7percentcarbonasvery-high-carbonsteels.ENGLISHINMATERIALSSCIENCEANDENGINEERINGII2.1.2CarbonandAlloySteel3Bothofthesesteelsrespondwellto

對…產生回應heattreatment.Asarule

一般說來

,steelsupto

直到0.65percentcarboncanbeweldedwithspecialelectrodes特殊焊條,althoughpreheating

預熱（pre-welding焊前,post-welding焊后)andstressrelievingtechniques(工藝technology;craft;industrialart;workmanship;process;technique)

mustoftenbeusedaftertheweldingiscompleted.Usuallyitisnotpracticaltoweldsteelsinthevery-high-carbonrange.ENGLISHINMATERIALSSCIENCEANDENGINEERINGII2.1.2CarbonandAlloySteel4Carbonistheprincipal

主要的，首要的；中小學校長elementcontrollingthestructureandpropertiesthatmightbeexpectedfromanycarbonsteel.Theinfluencethatcarbonhasinstrengtheningandhardeningsteelisdependentupontheamountofcarbonpresentanduponitsmicrostructure.Slowlycooledcarbonsteelshavearelativelysoftironpearlitic

珠光體的

（pearlite珠光體）microstructure微觀組織，顯微組織;ENGLISHINMATERIALSSCIENCEANDENGINEERINGII2.1.2CarbonandAlloySteel5whereas

反之rapidlyquenchedcarbonsteelshaveastrong,hard,brittle,martensitic

馬氏體的

(martensite馬氏體）microstructure.Incarbonsteelatnormal正常的（abnormal

不正常的）roomtemperature,theatomsarearrangedinabody-centeredlattice

晶格，空間點陣.Thisisknownas被稱作，以…著稱alphairon.Eachgrain

晶粒=crystalgrain

ofthestructureismadeupoflayersofpureiron(ferrite)andacombinationofironandcarbon.ENGLISHINMATERIALSSCIENCEANDENGINEERINGII2.1.2CarbonandAlloySteel6Thecompound化合物ofironandcarbon,orironcarbide

碳化物,iscalledcementite

滲碳體=Cm,Fe3C.Thecementiteisveryhardandhaspracticallynoductility.Inasteelwith0.8percentcarbon,thegrainsarepearlitic,meaningthatallthecarboniscombinedwithirontoformironcarbide.Thisisknownasaeutectoid共析的mixtureofcarbonandiron.SeeFigure2.1.ENGLISHINMATERIALSSCIENCEANDENGINEERINGII2.1.2CarbonandAlloySteel7Ifthereislessthan0.8percentcarbon,themixtureofpearlite

珠光體andferrite

鐵素體

referredtoas

把…稱作=beknownas

hypoeutectoid

亞共析.AnexaminationofsuchamixturewouldshowgrainsofpureironandgrainsofpearliteasshowninFigure2.2.ENGLISHINMATERIALSSCIENCEANDENGINEERINGII2.1.2CarbonandAlloySteel8Whenthemetalcontainsmorethan(反義詞：lessthan)0.8percentcarbon,themixtureconsistsofpearliteandironcarbideandiscalledhypereutectoid

過共析.NoticeinFigure2.3howthegrains(crystalgrain)ofpearlitearesurrounded圍繞byironcarbide

(Fe3C).Ingeneral一般而言,thegreatestpercentageofsteelusedisofthehypoeutectoid

亞共析type,thatwhichhaslessthan

（反義詞：morethan）0.8percentcarbon.ENGLISHINMATERIALSSCIENCEANDENGINEERINGII2.1.2CarbonandAlloySteel9ENGLISHINMATERIALSSCIENCEANDENGINEERINGII2.1.2CarbonandAlloySteel10◆AlloySteel合金鋼Analloysteelisasteeltowhichoneormoreofsuchelementsasnickel鎳,chromium鉻,manganese錳,molybdenum鉬,titanium鈦,cobalt[k?u‘b?:lt]

鈷,tungsten鎢,orvanadium釩havebeenadded.Theadditionoftheseelementsgivessteelgreatertoughness,strength,resistancetowear耐磨性,andresistancetocorrosion

耐腐蝕性.Alloysteelsarecalledbythepredominating占統治地位的elementwhichhasbeenadded.ENGLISHINMATERIALSSCIENCEANDENGINEERINGII2.1.2CarbonandAlloySteel11

Most

大部分的ofthemcanbewelded,providedspecialelectrodes電焊條areused.Thecommonelementsaddedtosteelandtheireffects影響areexplainedasthefollowing.

ManganeseTheadditionofmanganesetosteelproducesafinegrainstructurewhichhasgreatertoughness

韌性andductility

延展性.Manganesealwayspresentsinasteeltosomeextent

達到某種程度becauseitisusedasadeoxidiser

脫氧劑.ENGLISHINMATERIALSSCIENCEANDENGINEERINGII2.1.2CarbonandAlloySteel12

siliconAlwayspresenttosomeextent,becauseitisusedwithmanganeseasadeoxidiser.

ChromiumWhenquantitiesof

大量的chromiumareaddedtosteeltheresultingproductisametalhavingextreme

極端的hardnessandresistancetowearwithoutmakingitbrittle.Chromiumalsotendstorefine改善；提煉thegrainstructureofsteel,therebyincreasingitstoughness.ENGLISHINMATERIALSSCIENCEANDENGINEERINGII2.1.2CarbonandAlloySteel13Itisusedeitheraloneincarbonsteelorincombination

結合withotherelementssuchasnickel,vanadium,molybdenum,ortungsten.

NickelTheadditionofnickelincreasestheductilityofsteelwhileallowingittomaintainitsstrength.Whenlargequantitiesofnickelareadded(25to35percent),thesteelsnotonlybecometoughbutalsodevelophighresistancetocorrosionandshock

沖擊.ENGLISHINMATERIALSSCIENCEANDENGINEERINGII2.1.2CarbonandAlloySteel14

TungstenTungstenisusedmostlyinsteelsdesignedformetalcuttingtools.Tungstensteelsaretough,hard,andveryresistanttowear.

MolybdenumMolybdenumproducesthegreatesthardeningeffectofanyelementexceptcarbonandatthesametimeitreducestheenlargement增大ofthegrainstructure.ENGLISHINMATERIALSSCIENCEANDENGINEERINGII2.1.2CarbonandAlloySteel15Theresultisastrong,toughsteel.Althoughmolybdenumisusedaloneinsomealloys,oftenitissupplemented補充byotherelements,particularlynickelorchromiumorboth.

VanadiumVanadiumisastrongcarbideformingelement.Additionofthiselementtosteelpromotesfinegrainstructurewhenthesteelisheatedaboveitscritical臨界的；愛挑剔的，吹毛求疵的rangeforheattreatment.ENGLISHINMATERIALSSCIENCEANDENGINEERINGII2.1.2CarbonandAlloySteel16Italsoimparts傳遞toughnessand