[雙語翻譯]--外文翻譯--15 cr-15ni高氮耐熱奧氏體不銹鋼熱處理工藝對顯微組織和蠕變特性的影響（英文）

1、MaterialsScienceandEngineeringA528 (2011) 7115–7123ContentslistsavailableatScienceDirectMaterialsScienceandEngineeringAjournalhomepage:www.elsevier.com/locate/mseaEffectsofheattreatmentprocessesonmicrostructureandcreeppr

2、opertiesofa highnitrogen15Cr–15NiausteniticheatresistantstainlesssteelVuTheHa a,b,?, WooSangJung ba Nano-MaterialScienceandEngineeringFaculty,UniversityofScienceandTechnology,113-Gwahangno,Yuseong-gu,Daejeon,RepublicofK

3、oreab MaterialsResearchDivision,KoreaInstituteofScienceandTechnology,39-1Halwolgok-dong,Wolsong-gil5,Seoungbuk-gu,Seoul,136-791,RepublicofKoreaa r t i c l e i nf oArticlehistory:Received12November2010Receivedinr

4、evisedform18March2011Accepted22June2011Available online 28 June 2011Keywords:NiobiumcarbonitrideCopperprecipitateHeattreatmentHighnitrogen15Cr–15NiCreepstrengthab s t r a c tConventionalthermo-mechanicaltreatment(C

5、TMT) andmodifiedthermo-mechanicaltreatment(MTMT)processwereappliedfor manufacturingahigh nitrogenniobium-stabilized15Cr–15Niausteniticalloy.CTMT process consistsof5 h of solutiontreatmentat 1270 ?C followedbywater

6、quenchingandsubsequentaging at 820 ?Cfor 50 h. MTMTprocessdiffers fromCTMT process in hot plasticdeformationperformedimmediatelyafter the solutiontreatmentat 1270 ?C and longer agingtime. Microstructureand

7、creeppropertiesof the steel obtainedby bothprocessingrouteswere investigated.Creeprupturetestsat 750 ?C showeddoubleincreasein rupturetime broughtabout by MTMTprocess.Examinationofcreptmicrostructureby transm

8、issionelectronmicroscopyrevealedthat the improved creep propertiesinMTMT processwere mainlydue to improveddistributionuniformityof fine nano-sizedcarbonitrideprecipitatesin the austeniticmatrix and that MTMT

9、 processhas no effectson the numberdensityanddistributionof copper precipitatespresentin the steel.However,the creep ductility in MTMT processdrasticallyreducedcomparingto CTMT process.The higher densit

10、yof grain boundariesdue to finergrainrecrystallizedmicrostructuresand the formationof highervolumefractionof coarserM23C6 precipitatesatthe boundariesare believedto be the mainreasonfor the lowercreep ducti

11、lityin MTMT process.© 2011 Elsevier B.V. All rights reserved.1.IntroductionNitrogen-alloyedheatresistantausteniticstainlesssteelsarenovelmaterialswhichareunderintensestudiesanddevelop-mentduringrecentyears.Thesest

12、eelsarepotentialmaterialsforconstructioncomponentsinultra-supercriticalfossilpowerplants(steamturbines,boilertubes,etc.)duetotheirexcellentcreepstrengthandreasonablelowercostcomparingtothecostofnickel-basesuperalloys[1,2

13、].Itisofagreatinteresttoincreasethecreepstrengthofthesteelsbecauseofenvironmentalandeconomicalreasonsinoperationoftheplants[3].Thecreeppropertiesofthematerialsdependonanumberoffactors.Amongthemthemostimportantarefinedisp

14、ersionofthermallystablenano-sizedparticlesintheausteniticmatrix,grainsizeandgrainboundarycharacter,precipitationofdeleteriousphasesduringcreepandsoon.Maximumcreeprupturelifecanbeachievedonlythoughchoosingproperchemicalco

15、mpositionandoptimumconditionsforheattreatmentprocesses.Lotsofinvestiga-tions[4–7]inrecentyearshaveexaminedcreepbehaviorandcreep? Correspondingauthorat:Nano-MaterialScienceandEngineeringFaculty,Uni-versityofScienceandTech

16、nology,113-Gwahangno,Yuseong-gu,Daejeon,RepublicofKorea.Tel.:+8229586807;fax:+8229585509.E-mailaddress:vutheha@kist.re.kr(V.T.Ha).characteristicsofthesteels.However,theworksinvolvedinpro-cessingfieldforthematerialsrarely

17、canbefound.Therefore,thereisanimperativeneedtounderstandanadopt-abilityofthemate-rialstoindustriallyapplicableheattreatmentprocesses.Throughknowingresponsebehaviorofthematerialstotheheattreatmentprocessestheimportantmicr

18、ostructureconstituentsaffectingthecreeppropertiesofthematerialscanbeoptimizedwhichenabletoachievethebestperformanceofthecomponentsduringlongtermserviceathightemperatureandhighpressureconditions.Thefocusofthisstudyistoinv

19、estigatetheeffectsoftwodiffer-entheattreatmentprocessesoncreeppropertiesinahighnitrogenniobium-stabilizedheatresistant15Cr–15Niausteniticstainlesssteel.Thecreeppropertiesandmicrostructureofthesteelproducedbytheheattreatm

20、entshavebeenexaminedandcompared.Thedif-ferencebetweencreeppropertiesofthesteelintheappliedheattreatmentprocesseshasbeendiscussedandcorrelatedwiththemicrostructurechangesbroughtaboutbydifferentappliedthermo-mechanicalcond

21、itionsofthetwoheattreatmentroutes.2.AlloydesignconceptBasechemicalcompositionFe–15Cr–15Ni–4Mn–0.46Si–1.25Mo–3Cu–Nb–C–N(wt%)oftheinvestigatedausteniticsteelwasformulatedbyconsultingtheSchaefflerdiagram[8]. Forthe0921-509

22、3/$–seefrontmatter ©2011 Elsevier B.V. All rights reserved.doi:10.1016/j.msea.2011.06.061V.T.Ha,W.S.Jung/MaterialsScienceandEngineeringA528 (2011) 7115–7123 7117Fig.2.CreeprupturestrengthofthestudiedsteelobtainedbyC

23、TMTandMTMTprocessincomparisonwithrupturestrengthofstandardtype347stainlesssteel[11].Fig.3.Creepstrainvs.timecurvesforthestudiedsteelshowinglowercreepduc-tilityofthesamplesobtainedbyMTMTprocess.investigatedsteel.Creeprupt

24、ureelongationdataareremarkablyhigherforCTMTprocessasseeninFig.3.4.2.MicrostructuresFig.4aandbshowsgrainstructureinthecreptspecimensobtainedbyCTMTandMTMTprocess,respectively.Themainchar-acteristicofthegrainstructureinCTMT

25、-specimensisamultimodalgrainsizedistributionwithaveragegrainsizeofaround220?m.Thedeviationofthegrains’diametersfromtheaveragevalueindi-catedthatabnormalgraingrowthhasoccurredduringthesolutiontreatment.RecrystallizedMTMT-

26、specimensshoweduniformgrainsizestructurewithaveragegrainsizeofaround40?m.Themicrostructuresofquenchedsolutiontreatedspecimensinthebothheattreatmentscontainasmallnumberofun-dissolvedcoarserNb(C,N)precipitatesinheritedfrom

27、as-castconditionsandlargerquantity(about130particles/?m2)ofevenlydistributedfineparticleswithsize15–40nm(Fig.5a).Selectedareadiffrac-tionpattern(Fig.5b)andEDSanalysis(Fig.5c)indicatedthatthesenano-sizedprecipitatesarepur

28、eniobiumcarbonitrideswith-outexception.Todistinguishthecarbonitridespresentalreadyinthesolutiontreatedmicrostructurefromthoseformedduringthesubsequentagingandcreep,theformerwillbecalledprimarypre-cipitatesandthelatterwil

29、lbedesignatedassecondaryprecipitates.Theprecipitatemorphologyinas-agedandas-creptmicrostruc-turechangedsignificantlybyprecipitationofthesecondarynano-sizedcarbonitrides.Thenewlyformedparticlesusuallyhaverodorcuboidalshap

30、ewithlengthrangedfrom10to60nmandwidthrangedfrom10to30nm.Selectedareadiffractionpattern(SADP)ofthinfoilsamplespreparedfromCTMT-andMTMT-specimensshowedparallelorientationrelationshipofthelatticeplanesofthebothprimaryandsec

31、ondarynano-sizedcarbonitrideswiththelatticeplanesoftheausteniticmatrix(Fig.6d).EDSanalysis(Fig.6c)demonstratedthatthesecondarycarbonitridesarerichinNbandCr,havethesamechemicalcom-positionof(at.%):Nb58.5–59.5,Cr38–40,Fe2–

32、3,inbothCTMT-andMTMT-specimens.InCTMT-specimensmostofthesecondarycarbonitridespreferentiallyaggregatedwiththepre-existedpri-marycarbonitridestoformelongatedclustersconsistingofahighnumberoftightlydistributedparticles(Fig

33、.6a).Theclusterswerenon-uniformlydistributedthroughouttheausteniticmatrix.Theirdensitycanreachalevelofseveraltensclusters/?m2 insomeareaswhileincertainareasonlyafewclusters/?m2 canbefound.InMTMT-specimens,onthecontrary,t

34、hesecondaryandtheprimarycarbonitrideswereevenlydistributedwithinthematrix(Fig.6b).ItwasobservedthatthesecondarycarbonitridesinMTMT-specimensformedpreferentiallyatthepointswherethedislocationsintersectedwitheachotherassee

35、ninFig.7.Inmanycases,theparticlesformedalsoatthepre-existedprimarynano-sizedcarbonitridesFig.8).Certainnumberofcoarserelon-gatedpuresecondaryNb(C,N)precipitates(Fig.6b)wasobservedtoformduringaginginMTMTprocess.Quantitati

36、vely,recrystallizedMTMT-specimenscontainedsignificantlylowernumberofthenano-sizedcarbonitrideswhichisoppositewithourexpectationsinincreasinganumberoftheprecipitatesthroughperformedhotrolling.Apartfromthefinenano-sizedcar