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1：ANOUTSIDERLOOKSATFRICTIONSTIRWELDING译文1：常人眼中的摩擦搅拌焊接技术(原文1)ANOUTSIDERLOOKSATFRICTIONSTIRWELDINGBACKGROUND4.1SolidStateWelding,Overview2-4FSW,thesubjectmatterofthisdocument,isthenewestadditiontofrictionwelding(FRW),asolidstateweldingprocess.Solidstatewelding,asthetermimplies,istheformationofjointsinthesolidstate,withoutfusion.Solidstateweldingincludesprocessessuchascoldwelding,explosionwelding,ultrasonicwelding,rollwelding,forgewelding,coextrusionweldingandFRW.ConventionalFRWinitssimplestforminvolvestwoaxiallyalignedparts,onerotatingandtheotherstationary.Thestationarypartisadvancedtomakecontactwiththeother,atwhichpointanaxialforceisappliedandmaintainedtogeneratethefrictionalheatrequiredtoaffectweldingattheabuttingsurfacesandformasolid-statejoint.Thejointisachievedbyupsetforgingattheelevatedtemperaturesgeneratedbyfriction.TherearetwoFRWtechniques.Thefirstisdirect/continuosdriveFRW,whereconstantenergyisprovidedbyasourceforthedesiredduration.ThesecondisinertiadriveFRW,wherearotatingflywheelprovidestherequiredenergy.Avariantoftheconventionaltechniques,radialfrictionwelding,isusedforhollowsections,suchastubeandpipe.Here,asolidringisrotatedandcompressedaroundtheabuttingbeveledendsofthestationarypipes/tubestobewelded.Asupportmandrelislocatedatthebore,attheweldingposition,topreventthecollapseofthepipe/tubeends.Anothervariantisfrictionsurfacing,wheremetallayersaredepositedonasubstrate.Here,arotaryconsumableisbroughtintocontactwithamovingsubstratetoaffectmetaltransferfromtheconsumabletothesubstrate.4.2FrictionStir(FS)Technology5,6FSWisamemberoftheFStechnologyfamily.TheothermembersofthatfamilyareFSprocessingforsuperplasticity,FScastingmodification(alsoreferredtoasFTMPorfrictionthermomechanicalprocessing),FSmicroforming,FSpowderprocessing,FSchannelingandFSprocessingforlowtemperatureformability.4.3ANoteonAluminumAlloysSincethemajorityofworkreviewedinthisdocumentpertainstoaluminumalloys,itisimportanttodiscusssomeoftheheattreatmentaspectsofthesealloys.Athree-stepsequenceisusedtoheattreat2xxx,6xxxand7xxxseriesandotherheattreatablealuminumalloys,tohigherstrengthlevels.Thefirststepissolutionheattreatmentanditconsistsofheatingtosomeprescribedelevatedtemperature(around900F)andsoakingthereforaprescribedperiodoftime.Thesecondstepistocoolthealloyfastenough(e.g.,byquenching),soastoretaintheelevatedtemperaturemicrostructure.Aswillbecomeclearshortly,coldworking,formingorstraighteningofquenchedwroughtalloysshouldbeperformedassoonaspossibleafterquenching.Thethirdstepisaging(AKAprecipitationheattreatment).Aginginvolvessoakingthealloyforaperiodoftimeatsometemperaturethatislowerthanthatusedforsolutiontreatment.Forthealuminumalloysofconcernhere,agingisperformedintheroomtemperatureto375Ftemperaturerange.Agingatroomtemperatureisreferredtoasnaturalaging.Agingattemperaturesaboveroomtemperatureisreferredtoasartificialaging.Agingcausesprecipitationwithinthegrains,withtheattendantincreaseinstrengthandhardness,attheexpenseductility.Otherpropertiesalsochangeasaresultofaging.4.3.1NaturalAgingAfterquenching,thealloyisintheunstable-AQtemper.Atroomtemperature,thealloyremainsinthattemperforaperiodthatrangesfromafewminuetstoanhourorso,dependingontheparticularalloy.Duringthatperiod,thesolutiontreatedmicrostructureremainsasitwasatthesolutiontreatmenttemperature；i.e.,remainsunchanged.Attheendofthatperiod,thetemperchangestothe-Wtemper,alsoanunstabletemper.Thisisaccompaniedbychangesinproperties；e.g.,thestrengthandhardnesswillincreaseandtheductilitywilldecrease.Asmoreprecipitationoccurswithtime,thepropertieswillprogressivelyevolve；e.g.,strengthwillprogressivelyincreaseandductilitywillprogressivelydecreasewithtime.Afterafewdays(orabout96hr),2xxxand6xxxalloysreachastablecondition,referredtoasthe-T4temperwherenofurtherpropertychangeswouldtakeplace.Anadditionalincrementofstrengthcanbeobtainedin2xxxalloysifthealloyiscoldworkedinthe-AQtemperorduringtheearlystagesofthe-Wtemper,andthennaturallyaged,forabout96hr,toastableconditionreferredtoasthe-T3temper.Whileitisgenerallyacceptedthatnaturalagingfor96hrissufficienttodevelopastabletemper(-T3or-T4),itisreported,inFSWliterature,thatnaturalagingcontinuesforoveronemonthinAA60137andover2.5yearsinAA2195.8The7xxxalloysdonotreachthestable-T3and-T4tempers.Rather,strengthandotherpropertiescontinuetoevolvewithtimeforyearsatroomtemperature；infact,itisreported9thatAA7050aluminumalloyagehardensindefinitelyatroomtemperature.Inotherwords,itshouldbeassumedthat7xxxalloysremaininanunstableandevolving-Wtemperindefinitely,unlessthealloyisartificiallyaged.Therefore,testresultsobtainedinvarious7xxx-Walloyinvestigationscannotbedirectlycomparedunlesstheperiodsofnaturalagingindicated(e.g.,-W0.5hr)arethesame.Unfortunately,however,researcherstendnottoindicatetheseperiods.4.3.2ArtificialAgingAgingattemperaturesaboveroomtemperatureisartificialaging.Thepropertiesconstantlyevolvewithagingtimeattheagingtemperature.Forexample,strengthandhardnessincreasewithtimetosomepeakvalues,beyondwhichbothstrengthandhardnessdecrease,withfurtherincreasesinagingtime；strengthandhardnesspeaksmayormaynotoccuratthesameagingtime.Thedecreaseinstrengthandhardnessisreferredtoasoveraging.Foragivenalloy,thepeakstrength(hardness)valuesthatcanbeachievedbyartificialagingarehigherthanthatachievedbynaturalaging.Astheartificialagingtemperatureisincreased,peakstrength/hardnessshiftstoshortertimes,andthelossofstrength,duetooveraging,occursmorerapidly.Peakstrengthmayincreaseordecreaseastheagingtemperatureincreases,dependingonthealloyandtemperaturerange.Duetopeakshiftt