Lett是什么意思t在线翻译读音例句

Sinterin小儿垂钓古诗解释 gbehaviourandmicrostructuredevelopmentofT42powder

metallurgyhighspeedsteelunderdifferentprocessing

conditions

Highspeedsteelpowders(T42grade)havebeenuniaxiallycold-pressedandsubsequentlydensifiedthroughdifferent

sinteringroutesincluding：supersolidusliquidphasesintering(SLPS)undervacuumanddifferentnitrogenpressures(0.2,

0.9,and8bar)andthroughsolidstatesintering(SSS)byhotisostaticpressing(HIP)・HIPtemperaturesaslowas850C

ledtoearfulldensificationofthematerial(>98%theoreticaldensity)withaveragesizeofM6CandMCcarbideslower

than1卩mandgrainsize

\"3卩relesssi跌的拼音 nteringunderdifferentnitrogenpressures(upto0.39wt・％Nabsorption)ledtoasignificant

reductionoftheoptimumsinteringtemperature(OST)andapronouncedincreaseinthesinteringwindow(SW)ascomparedto

vacuumsintering・Pressurelesssinteringunder8barN2ledto

afurtherreduetioninOSTtogetherwiththeprecipitationofmassiveeutecticstructures・Therefore,theSWwasjudgedto

benegligible・Theresponseoftheas-sinteredmaterialstotheheattreatmentisbasicallydeterminedbytheamountofC

availableinthematrixpriortoquenchingandthegrainsize・Thehighesthardnessachievableforthesinteringconditions

evaluatedranges700—100HV2afteraustenitizingat

1100「C,oilquenchingandmultitemperingat500-550C・

Toolsteelsservealargerangeofapplicationsincludinghotandcoldworkingofmetalsandinjectionmouldingofplastics

orlightalloys・Highspeedsteels(HSS)aremorespecificallyusedascuttingtoolsandwearparts・Morerecently,these

materialshavealsobeenusedforstructuralapplications・Thehighperformanceexhaustvalveseatinsertsforpassenger

vehiclesconstitutethemostnotableexample[1]・Ingeneralterms,forthesestructuralapplications,acombinationof

highstrength,wearresistanceandhardnesstogether疲劳的拼音 withanappreciabletoughness(comparedwithothermaterialsusedas

tools)andfatigueresistanceisrequired・

Fromamicrostructuralpointofview,HSScanbedescribedasmetallicmatrixcompositesformedbyaferrousmatrixwitha

dispersionofhard,wearresistantcarbides・Thetype,size,morphology,distributionandvolumefractionofcarbidesas

wellasthecharacteristicsoftheferrousmatrixdependonboththecompositionofthematerialandthemanufacturing

process[2]and[3]・Thebasicalloyingelementsofhighspeedsteelsare

—30wt.%ofcarbideformers(Cr,Mo,W,V),sometimesCoand

approximately15

[8].

sufficientcarbontopromotetheformationofcarbides・Tungstenandmolybdenummainlycontributetotheformationofthe

primaryM6CandM2Ccarbidesandvanadiumisthemainconstituent细大不捐 oftheMCtype.

Conventionalmanufacturingprocessesfortheproductionofcomponentswiththesematerialsincludewroughtmetallurgyand

powdermetallurgy(directsinteringandhotisostaticpressing;HIP)・Themainmanufacturingstepsforwroughtprocessing

aremelting,casting,hotworking,machiningandheattreating・Normally,extensivehotworking(areareductions>90%)is

necessarytodispersethtworkingprocess

leadstothealignmentofcarbideinstrings,whichisresponsibleforanisotropicproperties[2]・Powdermetallurgy(PM)

techniqueswereinitially-developedtoovercometheseproblems・Thestartingrawmaterialsarepre-alloyedgasorwater

atomisedpowders・Gasatomisedpowdersarecleanerthanwateratomisedpowdersandbothofthemarefreeofsegregations

duetothehighcoolingratesinvolved・GasatomisedpowdersareusedforHIP[4]andpowderinjectionmoulding(PIM)[5]・

HIPisdevotedforaprimequalityproductduetothecleannessoftheraw

materialandtothefactthatdensificationtakesplacebyasolidstatesintering(SSS)process・

Consequently,afineandhomogeneousdistributionofcarbidesembeddedinapore-freeferrousmatrixisobtainedleadingto

exceptionalproperties・PIMisbestsuitedforsmallcomponentswithcomplexgeometriesanddensificationtakesplaceby

directsintering(i・e.,pressurelesssintering)throughasupersolidusliquidphasesintering(SLPS)mechanism[5]and[6]

・

Wateratomisedpowdersarenormallyprocessedbythedirectsinteringroute・Partialdensificationisachievedbycold-

pressingthepowderswithasuitablecompactionlubricant・Subsequently,sinteri安营扎寨的拼音 ngtofulldensitytakesplacebyaSLPS

mechanism・Thedirectsinteringroutehasinherentadvantagesintermsofachievablepropertiesversusprocessingcostsand

environmentaiconsiderationsrelatedtothehighlyefficientmaterialuse.

Duringthelast20years,ahighresearchefforthasbeenmainlyaddressedattheunderstendingofthephysicalandchemical

mechanismsinvolvedinthedensificationviaSLPS[7]andSSS[4]・Additionally,researchhasalsobeenfocusedonthe

microstructuralchangesoccurringduringheattreatmentsleadingtothedesiredmechanicalproperties(i・e.,strength,

toughness,wear,fatigue)dependentontheserviceapplications

Previousstudies[9],[10],[11]and[12]havebeenfocusedontheoptimisationofthedirectsintering:routeofHigh

VanadiumHSSgrades(mainlyM35MHV)byunderstandingtheeffectofthesintering

atmosphere・Thisapproachhasledtoasignificantdecreaseofthesinteringtemperaturesneededforfulldensificationin

nitrogenrichatmospherescomparedtovacuumsintering・Theoptimumsinteringtemperature(OST)forM35MHVdecreasedfrom

1220Ccorvacuumsinteringto1140Cwhensintered

undernitrogen-richatmosphere[3]and[10]・,

carbonadditions)hasbeenunderstoodbytheuseofcomputationalthermodynamics(calculationofmulticomponentphase

diagrams)[10]and[11]・Moreover,thecorrespondencebetweencomputationalthermodynamicsandexperimentaldata

constitutedapreliminarystepforalloydesignofnewHSScompositions[12]and[13]・

ThepresentstudyisaimedatthedescriptionofthesinteringbehaviourofthePMT42gradeunderdifferentnitrogen

pressures・Thismaterialhasbee自怨自艾是什么意思 nchosenfortheinvestigationsinceitisacommercialgradecontaininganadequate

amountofVformicrostructuraldesignthroughtheadditionofN・

Additionally,theexcellenthothardnessofT42duetothe10.58wt・%Co,makesthismaterialveryinterestingforboth

structuralandtribologicalapplications・Thesatisfactoryresultsofearlierinvestigationsonthesinteringbehaviourof

T42inN~richatmospheres[9]invitedforamoredetailedinvestigationstrivingforacommercialimpactoftheresearch・

ThemainobjectivewasthemicrostructuraldesignofPMHSSthroughthedensificationrouteandtheheattreatmentsequence

selected・Awidesetofdifferentmicro

effectoftheas-sinteredmicrostructure(mainlyabsorbedNcontentandgrainsize)ontheheattreatment(austenitizing+

quenching+multitempering)isalsodiscussed・

References

[1],K・Hayashi,K・Ishii，K・Maki,ndM・Toriumi,SAETrans・107(5)(1998),pp.

194-200.

[2],HighSpeedSteels,Butterworths,BoroughGreen,SevenoaksKent(1988)・

[3]S・za,J・Mater・Process・Technol・143/144(2003),pp.555-560.

218.

[4]E・Arzt,ndK・E・Easterling,・A14A(1983),pp.211

[5]乙Y・Liu,,dSBTor,Mater・Lett.45(2000),pp.32一3&

[13]elo,S・Gimenez,T・za,

287—292

-221

[6]eld,ndJ.H・Torralba,・Trans・A33

(6)(2002),pp.1843-1851.

[7],Metall.26(1)(1990),pp.23-34.

[8]G・Krauss,HeatTreatmentandProcessingPrinciples(6thed・),ASMInternational(2000)

・

[9]R.H・Palma,,

299.

PowderMetall.32(4)(1989),pp.291

[10]e,

S・Gimenez,T・Gomez-Acebo,S・za,PowderMetall.

44(3)(2001),

pp.211一220.

[11]e,S・Gimenez,T・Gomez-《观沧海》赏析 Acebo,S・TalacchiaandI.

Iturriza,

pp.3534357.

PowderMetall.

42(4)(1999),

[12]S・GimenezandI.

Iturriza,Po李叔同《送别》全词 wderMetall.46(3)(2003),pp.209

ScriptaMater.53(3)(2005),pp.

根据高速钢不同的加工条件T42冶金粉末烧结机制和微观结构的发展

高速钢粉（t42级）经单轴冷加压及随后的致密再通过不同烧结路线，包括：超固相

线烧结与液相烧结（液面压力）•在真空状态下，不同的氮压力（0.2,0.9和8个大气

压）,通过固相烧结（SSS由热等静压法（HIP），当静压炉的温度低至850C能使材料

充分致密（大于98%理论密度）从而使平均粒径MeC和MC碳化物小于1卩m而晶粒

尺寸为3卩m•相对于真空烧结，在不同氮气压力下的烧结窗口，常温烧结（高达0・

39Wt%氮素吸收）使最佳烧结温度显著下降（大气外层空间）并日益突出显著・8个N?

压烧结下，在美国科学技术局实验室里烧结温度得到进一步降低使得大量共晶结构连接

在一起。

因此SW判断是可以忽略不计。烧结反应的烧结材料，热处理，基本上是由碳量可

在基体前淬火和晶粒尺寸来确定。最高硬度可达烧结条件评价范围700-1100hv2o在

1100C时，奥氏体化后，油淬和多次回火保持在500-550C之间。

工具钢服务于一个庞大的系统，包括热轧和冷轧工作金属和注塑成型的塑料或轻合

金结构。高速钢（HSS是更多的作为切削工具和磨损零件。现在，这些材料在结构型上

也有所应用。最显著的例子是客运车辆中高性能排气阀座的应用[1]。总体来讲，这些结

构型的应用，结合强度高，耐磨性和硬度有一个值得称赞的韧性（相较于其他同类的材

料应用）和抗疲劳是我们所需要的。

从微观结构的角度来看，高速钢可以说是金属基复合材料，是一个黑色矩阵与色散

指针的耐磨碳化物。该类型、大小、形态、分布和体积分数碳化物以及其特色的黑色矩

阵取决于组成材料和制造过程[2][3]。高速钢的基本合金元

素约有15-30Wt%及硬质合金（Cr,Mo,W,V）。有时Co和足够的碳，能促进碳化物的

形成。钩、铝、主要是有助于形成me和me碳化物，且锐是MC类型主要的组成部

分。传统的制造工艺生产的组件与这些材料包括造成的冶金和粉末冶金（直接烧结和均

衡加压热烧结法及热等静压法）。主要的生产步骤为变形处理的熔炼，铸造，热加工，

机械加工和热处理。一般情况下，必要的大量热加工（面积减少＞90%）以达到驱散凝固

过程中的铸锭中碳化物形成的网络。这个加热

的工作过程生成各种碳化物，这是金属的各向异性性能[2].粉末冶金技术（PM）的初步形

成得以克服这些问题。未经过加工的合金原料气体或水微粒粉末，气体微

在主要目标是微观设计时，高速钢通过致密的路线和热处理序列选定。广泛的一套

不同的微观结构，已获得使用不同的烧结条件。影响了作为烧结的微观结构（主要是吸

收氮含量和晶粒尺寸）对热处理（奥氏体+淬火+多次回火）进行

讨论

参考文献

,K・Hayashi,K・Ishii,K・Mdki,ndM・Toriumi,SAETrans・107(5)(1998),pp.

,HighSpeedSteels,Butterworths,BoroughGreen,SevenoaksKent(1988)・

S・za,J・Mater・Process・Technol・143/144(2003),pp.555-560.

乙,,,Mater・Lett.45(2000),pp.32一38.

eld,ba,・A33(6)(2002),pp.1843

[7],Metall.26(1)(1990),pp.23

[1]

194-200.

[3]

[4]

,ling,・A14A(1983),pp.211-221

-1851.

—34.

[8[,HeatTreatmentandProcessingPrinciples(6thed・),

ASMInternational(2000)・

[9],zand

J・J.

Urcola,PowderMetall.32⑷(1989),pp.291-299.

[10]I.

Aguirre,S・-Acebo,S・Talacchiaand

I.

Iturriza,PowderMetall.44(3)(2001),

pp.211-220.

[11]I.

Aguirre,S・

GimnezT.

mez-Acebo,S・Talacchiaand

I.

Iturriza,PowderMetall.42(4)(1999),

pp.3534357.

L12JS・za,PowderMetall.46(3)(2003),pp.209-218.

[13]elo,S・Gimnez,T・za,ScriptaMater.53(3)(2005),pp.

287-292