JournalofMagnetismandMagneticMaterials323(2011)2648–2651ContentslistsavailableatScienceDirectJournalofMagnetismandMagneticMaterialsjournalhomepage:www.elsevier.com/locate/jmmmMicrostructureandtextureevolutionofstripcasting3wt%Sinon-orientedsiliconsteelwithcolumnarstructureHaitaoLiun,ZhenyuLiu,GuangmingCao,ChenggangLi,GuodongWangStateKeyLaboratoryofRollingandAutomation,NortheasternUniversity,Shenyang110004,PRChinaarticleinfoArticlehistory:Received26December2010Receivedinrevisedform1June2011Availableonline12June2011Keywords:SiliconsteelNon-orientedsteelStripcastingMicrostructureTextureabstractAnFe-3wt%Sistripwithcolumnarstructureandpronounced{001}/0vwStexturewasproducedusingatwin-rollstripcaster.Thentheas-caststripwascold-rolledandannealed.Themicrostructureandtextureevolutionalongtheprocessingstepswasinvestigated.Itisfoundthatinhomogeneousmicrostructureisproducedinbothcold-rolledandfinalannealedsamplesduetothelargeinitialgrains.Thecoldrollingtextureisdominatedbypronounceda-fibertextureandrelativelystrongg-fibertexture.Thefinalrecrystallizationtextureischaracterizedby{001}/010S,{001}/210S,{110}/001Stextureandaslightlyshifted{111}/112Scomponent.Themicrostructuralinhomogeneityplaysanimportantroleinthetextureevolution.&2011ElsevierB.V.Allrightsreserved.1.IntroductionAsmentionedinapreviouspaper[1],{001}/0vwS,theidealcrystallographictextureforuseinelectricalmotors,isfoundinthesectiontransversetothecolumnargrowthdirectionofferriticsteelssolidification.Thestripcastingprocessproducesthinstripsdirectlyfromthemelt[2–4]and,infavorableconditions,cangeneratethedesiredtextureandmicrostructureintheas-caststate[5–7].Yonamineetal.[8]investigatedthemicrostructureandtextureevolutionofthe3wt%Sisteelhavinglargeinitial{001}/0vwScolumnargrains,whichwereobtainedusingthedirectionalsolidifi-cationmethodtosimulatethestripcastingprocess.However,sofar,thesiliconsteelstrippossessingfullycolumnarstructureandpronounced{001}/0vwSfibertexturehasnotbeeneffectivelyproducedbythestripcastingprocessinpracticalterms.Therefore,themicrostructureandtextureevolutionoftheas-caststripwithcolumnarstructurehasnotyetbeenunderstood.Inthepresentwork,anon-orientedsiliconsteelstripwithcolumnarstructurewasobtainedbythetwin-rollstripcastingprocess.Themaingoalofthispaperistoclarifythemicrostructureandtextureevolutionofthecolumnarstripaftercoldrollingandannealing.internallywater-cooledsteelrolls.Thesuperheatofthemeltpoolwascontrolledtobe551C.Aftercasting,thestripwasair-cooledtotheroomtemperature.Thenthestripwascold-rolledto0.5mmthicknessandannealedat10001C.Inordertofullyunderstandthesolidificationstructureoftheas-caststrip,eightsamplescutatdifferentpositionswerepreparedforElectronBackscatterDiffraction(EBSD)observation.Thecrystalorientationmapsoftheas-castsamplesweredeter-minedbytheOIM4000EBSDsystemequippedatFEIQuanta600ScanningElectronMicroscope.X-raydiffractionwasperformedinaBrukerD8DiscoverX-rayDiffractometer.Thetexturemeasure-mentswereperformedatthesurfaceandcenterlayersoftheas-castsample,andthecenterlayersofbothcold-rolledandannealedsampleswith20Â22mm2area.Themicrostructureofbothcold-rolledandannealedstripswasobservedwithanopticalmicroscope.Thevalueofthemagneticinductionat5000A/m,B50,wasmeasuredbyusingasinglesheettesterintherollingdirectionofassheared300mmÂ30mmsamples.3.Resultsanddiscussion3.1.Microstructureandtextureofas-caststrip2.ExperimentalproceduresAnFe-3wt%Sisteelstripwithathicknessof2.1mmwasproducedusingaverticaltypetwin-rollstripcasterwithnCorrespondingauthor.Tel.:þ862483688543;fax:þ862423906472.E-mailaddress:liuhaitao81214@yahoo.com.cn(H.Liu).Fig.1showsatypicalcrystalorientationmapoftheas-caststrip.Largecolumnargrainswithaveragediameterof380mmareobservedtostartattwosurfacesandimpingeinthecenter.Also,veryfewsmallgrainsareobservedatthesurfaceandcenter.Asthecolumnargrainsaresolarge,standardEBSDmeasurementcanonlycoveranareathatmayberelativetoasmallnumberofcastgrains.Thus,theothersevensamplescutfromthesame0304-8853/$-seefrontmatter&2011ElsevierB.V.Allrightsreserved.doi:10.1016/j.jmmm.2011.06.002H.Liuetal./JournalofMagnetismandMagneticMaterials323(2011)2648–26512649as-caststripwerefurthermeasured.Tobeinteresting,thesamecolumnarstructureisalsofoundinallthesamples.Thiscolumnarstructureisquitedifferentfromthefullyequiaxedstructureandthetypicalthree-layerstructurereportedintheearlyliteratures[1,3,7,9–11].Thecolumnarstructureisattributedtothehighsuperheatofthemeltpool,whichcanprovideahightemperatureFig.1.EBSDmicrographofas-caststrip(a)andtheinversepolefigure[001](b).Fig.2.Texturesinsurfacelayer(a)andcenterlayer(b)ofas-caststrip,j2-sections.2650H.Liuetal./JournalofMagnetismandMagneticMaterials323(2011)2648–2651gradientinfrontofthedendritestipsduringthewholesolidifica-tionprocessandsatisfytheselectivegrowthmechanismforthe{001}/0vwScolumnargrains.Fig.2showsthetexturesoftheas-caststrip.Relativelystrong{001}/0vwSfibertextureevolvesatthesurfacelayer,andpronounced{001}/0vwSfibertextureevolvesatthecenterlayer.Themaximumintensityof11.4timesoftherandomdistributionisobservedcloseto{001}/110Satthecenterlayer.3.2.Microstructureofcold-rolledandfinallyannealedstripsAftercoldrolling,aninhomogeneousmicrostructureispro-duced,asshowninFig.3a,wherealargeelongatedgrainatthetopshowsalargeamountofin-grainshearbandswithinclinationwithrespecttotherollingdirectionof20$301,whileagrainatthebottomshowsverylittlesignsofdeformation.Theinhomo-geneityofthedeformedmicrostructureisduetotheworkhardeningdifferencebetweenthelargeinitialgrainsofdifferentorientations.Thisinhomogeneousmicrostructureshowsdifferentnucleationandgrowthbehaviorduringannealingandfinallygivesrisetomanyclustersofgrainswithdifferentgrainsize,asshowninFig.3b.Theclustersaresimilartothoseinthecaseoftherecrystallizationsamplesaftercold-rolledlargehot-bandgrainsize[12,13].EBSDresultsindicatedthepresenceofclustersofgrainswithsimilarorientations[14].3.3.Texturesofcold-rolledandfinallyannealedstripsFig.4showsthecoldrollingtextureoftheas-caststripinj2¼451section.Thoughtheinitialas-caststripexhibitspro-nounced{001}/0vwSfibertexture,aftercoldrollingwithaheavyreductionof76.2%,{001}/0vwSfibertextureissignifi-cantlyweakened.Thetextureisdominatedbypronounceda-fiber(inparticular{113}/110S${111}/110S)withthemaxi-mumintensityof11.7timesthatoftherandomdistributionatposition{223}/110S,togetherwithrelativelystronganduneveng-fiber.Bycontrast,accordingtotheresultsbyYonamineetal.[8],itcanbenoticedthepronounceda-fibertextureFig.3.Microstructureofsamplesaftercoldrolling(a)andannealing(b)(long-itudinalsection).Fig.4.Textureofsampleaftercoldrolling,j2¼451section.Fig.5.Textureofsampleaftercoldrollingandannealing,j2¼451section.consistingof{001}/110S${113}/110Scomponentsandthenon-existenceoftheg-fiberbyrollingthedirectionallysolidified{001}/0vwScolumnarspecimens.Thatis,theas-caststriphaving{001}/0vwScolumnargrainsandafewotherorientedgrainsismorehelpfultothecrystalrotationtowardsthestableorientationsascomparedwiththedirectionallysolidifiedspecimens,whichischaracterizedbylargerandmoreorderly{001}/0vwScolumnargrains.Thus,theinitial{001}/0vwSfibertextureislessretainedintheas-caststripaftercoldrolling.Fig.5showsthefinalannealingtextureoftheas-caststripinj2¼451section.Tobeinteresting,twocomponentsofthecubefiber,{001}/010Sand{001}/210S,areclearlyobservedwithinten-sityof3.1and2.2timesoftherandomdistribution,respectively.Anditcanbenoticedthenon-existenceoftheregularlydistributedg-fibertexture.Instead,amildandslightlyshifted{111}/112Scomponentisfound.Thetwocomponents,{001}/010Sand{001}/210S,arefavorabletexturestothemagneticpropertiesofnon-orientedsiliconsteels.However,intheconventionalproductionprocess,{001}/010Scomponentishardtobeobtained,andatwo-stagecoldrollingmethodhastobeadoptedinordertogenerate{001}/210Scomponentandweakenthedeleteriousg-fibertex-ture[8,12,15].Themaximumintensityof6.2timesoftherandomdistributionisobservedatposition{441}/118S,neartheGossorientation{110}/001S,whichshowstheintensityofalmost4timesoftherandomdistribution.AccordingtotheresultsbyYonamineetal.[8],however,theGossorientationdoesnotappearinthefinalrecrystallizationtexturebycoldrollingthedirectionallysolidified{001}/0vwScolumnarspecimen.ItdoesnotexistintheH.Liuetal./JournalofMagnetismandMagneticMaterials323(2011)2648–26512651conventionalfinalannealedsheeteither.Therefore,incomparisonwiththeconventionalproductionprocess,thestripcastingprocesshasanadvantageinobtainingthedesiredtextures,whichleadstoahighB50of1.73T.Theeffectofthemicrostructuralinhomogeneitycausedbythelargeinitialgrainsoftheas-caststripseemstobethedominantfactoronthefinalrecrystallizationtexture.Theelongateddeformedgrainswithsmoothlyetchedmorphology,asshownatthebottominFig.3a,isprobableinthe{001}orientations.Thesekindsofdeformedgrainsarehardtorecrystallizebuteasytorecoveryduringtheannealingduetolowstoredenergy[16],andleadtothecoarsegrainsasshowninthemiddleofFig.3b,whichareprobablein{001}/010Sand{001}/210Sorientations.Bycontrast,theelongateddeformedgrainswithalargeamountofin-grainshearbands,asshownatthetopinFig.3a,tendtorecrystallizeinin-grainshearbandsduringannealingandleadtofine{110}/001Sgrainsalongtheshearbands[13,17,18],asshownatthebottomofFig.3b.Soitseemsreasonabletoconcludethattheweakeningofg-fibertextureisattributedtotheappearanceanddevelopmentof{110}/001Sgrains.4.ConclusionsInsummary,themicrostructureandtextureevolutionofthestripcasting3wt%Sisteelwithcolumnarstructurewasinvesti-gated.Heterogeneousstructuresobservedaftercoldrollingandannealingareattributedtotheorientationdifferencebetweenthelargeinitialgrains.Themicrostructuralinhomogeneityseemstobethedominantfactoronthetextureevolution.Thecoldrollingtextureshowsapronounceda-fibertextureandrelativelystrongg-fibertexture.Thefinalannealingtexturerevealsobvious{001}/010S,{001}/210Sand{110}/001Scomponents,asexpected.Theregularlydistributedg-fibertextureisnotobserved.Instead,amildandslightlyshifted{111}/112Scomponentisfound.Theresultsindicatethatthestripcastingprocesshasanadvantageinobtainingthedesiredtexturesandhighmagneticinductionincomparisonwiththeconventionalproductionprocess.AcknowledgmentsTheauthorsgratefullyacknowledgethefinancialsupportsfromtheNationalNaturalScienceFoundationofChina(NSFC)withContractnos.50734001and51004035,ChinaPostdoctoralScienceFoundationFundedProjectandNortheasternUniversityPostdoctoralFoundation.References[1]F.J.G.Landgraf,T.Yonamine,R.Takanohashi,F.Q.Silva,J.P.V.Tosetti,F.BeneduceNeto,E.Albertin,V.N.G.Mazzarella,I.G.S.Falleiros,M.Emura,J.Magn.Magn.Mater.254–255(2003)364–366.[2]D.Raabe,Mater.Sci.Technol.11(1995)461–468.[3]N.Zapuskal,ISIJInt.39(1999)463–470.[4]A.R.Buchner,¨J.W.Schmitz,SteelRes.63(1992)7–11.[5]H.T.Liu,Z.Y.Liu,Y.Q.Qiu,G.M.Cao,C.G.Li,G.D.Wang,Mater.Charact.60(2009)79–82.[6]H.T.Liu,Z.Y.Liu,G.D.Wang,ISIJInt.49(2009)890–896.[7]J.Y.Park,K.H.Oh,H.Y.Ra,ISIJInt.41(2001)70–75.[8]T.Yonamine,N.A.Castro,F.J.G.Landgraf,SteelRes.76(2005)461–463.[9]H.Fiedler,M.Jurisch,P.Preiss,R.Goebel,G.Sickert,H.Zimmermann,W.Neumann,R.Sellger,Mater.Sci.Eng.A133(1991)671–675.[10]J.Y.Park,K.H.Oh,H.Y.Ra,ISIJInt.40(2000)1210–1215.[11]J.Y.Park,K.H.Oh,H.Y.Ra,Scr.Mater.40(1999)881–885.[12]R.Takanohashi,F.J.G.Landgraf,J.Magn.Magn.Mater.304(2006)e608–e610.[13]W.B.Hutchinson,K.Ushioda,Scand.J.Metall.13(1984)269–275.[14]R.Takanohashi,F.J.G.Landgraf,M.F.deCampos,I.G.S.Falleiros,A.L.Pinto,C.S.C.Viana,in:Proceedingsofthe21stRisoInternationalSymposiumonMaterialsScience:Recrystallization-FundamentalAspectsandRelationstoDeformationMicrostructure,RisoNationalLaboratory,Roskilde,Denmark,2000,pp.601–606.[15]M.Takashima,M.Komatsubara,N.Morito,ISIJInt.37(1997)1263–1268.[16]N.Tsuji,K.Tsuzaki,T.Maki,ISIJInt.34(1994)1008–1017.[17]M.R.Barnett,J.J.Jonas,ISIJInt.37(1997)697–705.[18]D.Dorner,S.Zaefferer,L.Lahn,D.Raabe,J.Magn.Magn.Mater.304(2006)183–186.