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外文翻译--常人眼中的搅拌摩擦焊.doc

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外文翻译--常人眼中的搅拌摩擦焊.doc

外文翻译毕业设计题目双搅拌轴搅拌摩擦焊机设计原文1ANOUTSIDERLOOKSATFRICTIONSTIRWELDING译文1常人眼中的摩擦搅拌焊接技术原文1ANOUTSIDERLOOKSATFRICTIONSTIRWELDINGBACKGROUND4.1SolidStateWelding,Overview24FSW,thesubjectmatterofthisdocument,isthenewestadditiontofrictionweldingFRW,asolidstateweldingprocess.Solidstatewelding,asthetermimplies,istheformationofjointsinthesolidstate,withoutfusion.Solidstateweldingincludesprocessessuchascoldwelding,explosionwelding,ultrasonicwelding,rollwelding,forgewelding,coextrusionweldingandFRW.ConventionalFRWinitssimplestforminvolvestwoaxiallyalignedparts,onerotatingandtheotherstationary.Thestationarypartisadvancedtomakecontactwiththeother,atwhichpointanaxialforceisappliedandmaintainedtogeneratethefrictionalheatrequiredtoaffectweldingattheabuttingsurfacesandformasolidstatejoint.Thejointisachievedbyupsetforgingattheelevatedtemperaturesgeneratedbyfriction.TherearetwoFRWtechniques.Thefirstisdirect/continuosdriveFRW,whereconstantenergyisprovidedbyasourceforthedesiredduration.ThesecondisinertiadriveFRW,wherearotatingflywheelprovidestherequiredenergy.Avariantoftheconventionaltechniques,radialfrictionwelding,isusedforhollowsections,suchastubeandpipe.Here,asolidringisrotatedandcompressedaroundtheabuttingbeveledendsofthestationarypipes/tubestobewelded.Asupportmandrelislocatedatthebore,attheweldingposition,topreventthecollapseofthepipe/tubeends.Anothervariantisfrictionsurfacing,wheremetallayersaredepositedonasubstrate.Here,arotaryconsumableisbroughtintocontactwithamovingsubstratetoaffectmetaltransferfromtheconsumabletothesubstrate.4.2FrictionStirFSTechnology5,6FSWisamemberoftheFStechnologyfamily.TheothermembersofthatfamilyareFSprocessingforsuperplasticity,FScastingmodificationalsoreferredtoasFTMPorfrictionthermomechanicalprocessing,FSmicroforming,FSpowderprocessing,FSchannelingandFSprocessingforlowtemperatureformability.4.3ANoteonAluminumAlloysSincethemajorityofworkreviewedinthisdocumentpertainstoaluminumalloys,itisimportanttodiscusssomeoftheheattreatmentaspectsofthesealloys.Athreestepsequenceisusedtoheattreat2xxx,6xxxand7xxxseriesandotherheattreatablealuminumalloys,tohigherstrengthlevels.Thefirststepissolutionheattreatmentanditconsistsofheatingtosomeprescribedelevatedtemperaturearound900Fandsoakingthereforaprescribedperiodoftime.Thesecondstepistocoolthealloyfastenoughe.g.,byquenching,soastoretaintheelevatedtemperaturemicrostructure.Aswillbecomeclearshortly,coldworking,formingorstraighteningofquenchedwroughtalloysshouldbeperformedassoonaspossibleafterquenching.ThethirdstepisagingAKAprecipitationheattreatment.Aginginvolvessoakingthealloyforaperiodoftimeatsometemperaturethatislowerthanthatusedforsolutiontreatment.Forthealuminumalloysofconcernhere,agingisperformedintheroomtemperatureto375Ftemperaturerange.Agingatroomtemperatureisreferredtoasnaturalaging.Agingattemperaturesaboveroomtemperatureisreferredtoasartificialaging.Agingcausesprecipitationwithinthegrains,withtheattendantincreaseinstrengthandhardness,attheexpenseductility.Otherpropertiesalsochangeasaresultofaging.4.3.1NaturalAgingAfterquenching,thealloyisintheunstableAQtemper.Atroomtemperature,thealloyremainsinthattemperforaperiodthatrangesfromafewminuetstoanhourorso,dependingontheparticularalloy.Duringthatperiod,thesolutiontreatedmicrostructureremainsasitwasatthesolutiontreatmenttemperaturei.e.,remainsunchanged.Attheendofthatperiod,thetemperchangestotheWtemper,alsoanunstabletemper.Thisisaccompaniedbychangesinpropertiese.g.,thestrengthandhardnesswillincreaseandtheductilitywilldecrease.Asmoreprecipitationoccurswithtime,thepropertieswillprogressivelyevolvee.g.,strengthwillprogressivelyincreaseandductilitywillprogressivelydecreasewithtime.Afterafewdaysorabout96hr,2xxxand6xxxalloysreachastablecondition,referredtoastheT4temperwherenofurtherpropertychangeswouldtakeplace.Anadditionalincrementofstrengthcanbeobtainedin2xxxalloysifthealloyiscoldworkedintheAQtemperorduringtheearlystagesoftheWtemper,andthennaturallyaged,forabout96hr,toastableconditionreferredtoastheT3temper.Whileitisgenerallyacceptedthatnaturalagingfor96hrissufficienttodevelopastabletemperT3orT4,itisreported,inFSWliterature,thatnaturalagingcontinuesforoveronemonthinAA60137andover2.5yearsinAA2195.8The7xxxalloysdonotreachthestableT3andT4tempers.Rather,strengthandotherpropertiescontinuetoevolvewithtimeforyearsatroomtemperatureinfact,itisreported9thatAA7050aluminumalloyagehardensindefinitelyatroomtemperature.Inotherwords,itshouldbeassumedthat7xxxalloysremaininanunstableandevolvingWtemperindefinitely,unlessthealloyisartificiallyaged.Therefore,testresultsobtainedinvarious7xxxWalloyinvestigationscannotbedirectlycomparedunlesstheperiodsofnaturalagingindicatede.g.,W0.5hrarethesame.Unfortunately,however,researcherstendnottoindicatetheseperiods.4.3.2ArtificialAgingAgingattemperaturesaboveroomtemperatureisartificialaging.Thepropertiesconstantlyevolvewithagingtimeattheagingtemperature.Forexample,strengthandhardnessincreasewithtimetosomepeakvalues,beyondwhichbothstrengthandhardnessdecrease,withfurtherincreasesinagingtimestrengthandhardnesspeaksmayormaynotoccuratthesameagingtime.Thedecreaseinstrengthandhardnessisreferredtoasoveraging.Foragivenalloy,thepeakstrengthhardnessvaluesthatcanbeachievedbyartificialagingarehigherthanthatachievedbynaturalaging.Astheartificialagingtemperatureisincreased,peakstrength/hardnessshiftstoshortertimes,andthelossofstrength,duetooveraging,occursmorerapidly.Peakstrengthmayincreaseordecreaseastheagingtemperatureincreases,dependingonthealloyandtemperaturerange.Duetopeakshifttoshortertimesandthemorerapidoveraging,precisetimeandtemperaturecontrolisessentialatthehigheragingtemperatures,toavoidundesirableoveragingorunderaging.aIngeneral,theT4orWtempersmaybeagedtotheT6temper2xxxand6xxxalloys.TheT3temper2xxxalloysmaybeagedtoT8temper.In7xxxalloys,theWtempermaybedirectlyagedtotheT6orT7temper.Alternately,theT6tempermaybeartificiallyoveragedtotheT7temper.TheT7typetempersareforenhancedcorrosionperformance,withsomesacrificeinstrength.4.4AbbreviationsSomeabbreviationsofageneralnatureareusedthroughoutthisdocument.Thesearepresentedalphabeticallybelow,togetherwithwhattheymean.

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