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42520075IronandSteelVol.42,No.5May20071,2(1.,100081;2.,100083):,LF,,LF,,CASRH,,LCAKELCULC,CASRH:;;:TF769:A:04492749X(2007)0520001206DiscussiononProperSecondaryRefiningMethodsofSteelGradesforColdRolledSheetsYINRui2yu1,WANGXin2hua2(1.CentralIronandSteelResearchInstitute,Beijing100081,China;2.SchoolofMetallurgicalandEcologicalEngineering,UniversityofScienceandTechnologyBeijing,Beijing100083,China)Abstract:w([O])inliquidsteellargelyinfluencesthedesulphurizationrateduringladlerefining.Tomakehighde2sulphurizationrateofsteelsinladlefurnacerefiningforcoldrolledsheets,w([O])hastobedecreasedtoaverylowlevel,whicheasilyresultsinw([Si])outoffthespecificationrangeofthesteels.IfLFrefiningisappliedtothesteelsforcoldrolledsheets,thecontradictionbetweenstirringtheliquidsteeltoaccelerateremovingofnon2metallicinclusionsandpreventingreoxidationofthesteelbyoxidizingslagandtheatmosphereisoccurred.Hence,highre2ducingslagshouldbemade,whichincreasestheproductioncostandslowsdowntheproductionpacesofBOFandcontinuouscastingowingtotheincreaseoftheLFrefiningtime.DifferentfromLF,usingCASandRHrefiningmethods,theliquidsteelscanbestronglystirredwhilethereoxidationofthesteelsbytheoxidizingslagsandatmos2pherecanbeprevented.Also,theproductionpacesofCASandRHarequickerandeasiertomatchwiththepacesofBOFandslabcontinuouscasting.So,CASandRHshouldbechosenasthemainrefiningmethodforproducingsteelsforcoldrolledsheets.Keywords:coldrolledsheets;secondaryrefining;desulphurization:(19352),,,;E2mail:yuanwu@cisri.com.cn;:2007204218,,,,CSiSO,,LFCASRH,1,,3:(LCAK),w(C)0.02%0106%;(ELC),w(C)0.01%0102%;(ULC),w(C)0.0035%,(IF)13()(1),,,©1994-2008ChinaAcademicJournalElectronicPublishingHouse.Allrightsreserved.)SAlsNNbTiLCAKDQDDQ0.020.060.030.100.300.0200.0150.020.070.004ELCDDQ0.010.020.030.100.300.0200.0150.020.070.004ULCEDDQ0.00350.030.100.300.0200.0150.020.070.0030.020.040.030.061)ULCw([P])(r),{111},,,,w([C])0.0035%,TiNb,(2),,,,,0.03%(3),,,,LCAKELC0.015%,,(w([P])0.01%),IF,,,,IF[1],IF,w([P])0.01%(4),,(),,0.015%,,(w([S])0.01%),(5),IF,,(w([N])0.003%),TiNbLCAKELCw([N])0.004%(6),,[O]Al2O3w([O])110-6310-6,T[O],[2],:w(T[O])0.003%,;w(T[O])0.003%0.005%,;w(T[O])0.0055%,2,,w([S])0.015%,,:,w([S])0.007%,w([S])01003%;LF1[3]2,IF,,w([S])0.040%0.006%w([S])0.01%,LF,LF,(w([C])w([Si])w([N])),2©1994-2008ChinaAcademicJournalElectronicPublishingHouse.Allrightsreserved.([S])Fig.1SulfurcontroloftypicalsteelgradesadoptedbyThyssen2Krup:[S]+(O2-)=(S2-)+[O](1)Richardson[4](2):1/2S2(g)+(O2-)=(S2-)+1/2O2(g)(2)(2):K2=aS2-aO2-PO2PS2=fS2-w(S)aO2-PO2PS2(3)Richardson[4]CS,:CS=K2aO2-fS2-=w(S)PO2PS2(4),CS,CS(1)(2)(5):[S]+1/2O2(g)=[O]+1/2S2(g)(5)(5)[5]:logK5=log(a[O]a[S]PS2PO2)=1.467-828.6T(6)(4)(6):logLS=logw(S)w([S])=1.467-828.6T+logf[S]+logCS-loga[O](7),f[S][S];a[O][O](7),CS,,Sommerville[6]CS(8),(9)[7]:logCS=22690-54640T+43.6-25.2(8)=iXAxOiyAxOyiXAxOy(9),iAxOy;XAxOy;AxOy,CaO2Al2O32SiO2[8]CaOSiO2Al2O3=60%10%30%,[9]CaOSiO2Al2O3=60%65%4%6%30%35%2w([S])0.001%,(9)=0.783(8),logCS=-1.789[S][O]1,CS(7),/(2),,,w(S)/w([S])250,w([O])010008%,w([O])0.0001%010003%(w([Al])0.025%),,FetO0.4%1.0%2LFTable2TypicalchemicalcompositionofslagatendofLFrefining%CaOSiO2Al2O3CaF2MnOMgOP2O5SFetO57.798.2525.411.950.144.880.020.1320.4865.388.7215.811.590.137.680.010.2600.423©1994-2008ChinaAcademicJournalElectronicPublishingHouse.Allrightsreserved.([O])Fig.2Calculatedrelationbetweensulfurpartitionratioand[O]content3LF,(FetO),,LF15min,FetO17%1.5%,2025min1%3,FetO115%,SiO2,,25min,0.03%,,/,,,,LF,,,[9]LFCAS2000,LF,010409%010045%,CAS0.0343%0.0030%,,,,,,3,3LF(FeO)Fig.3Changeof[Si],[S]and(FeO)contentsduringLFrefining,,(10),(11)[5],23min,0.0001%010003%,Al2O3,Al2O32[Al]+3[O]=Al2O3(s)(10)G=-1209594+395.3T(11)LCAK,0.02%0.05%,FetO15%25%,FetO8%18%,,[Al]FetO,(12),Al2O3,(13)[5],,,[Al],Al2O3,,,,LCAK,LFCASRH[Al]+(FeO)=(Al2O3)+Fe(12)G=-533094+271.4T(13)(1)LF4LFLF4©1994-2008ChinaAcademicJournalElectronicPublishingHouse.Allrightsreserved.[Al]FetO,Al2O3,LFLCAK,(),(FetO)115%,1kg,,,LF,[Al],LF(2)LCAK,,,(12),,,,Al2O3(3)CASLF,CAS,CAS(5),5CASFig.5SchemeofCAS,,,,Ar,,,,Al2O3,,LCAKCAS,[11,12](4)RHELCULC,RH,LCAK,RHRH(6),Ar,,,CAS,RH,,RHLCAK,,LF45min,CASRH,LCAK2530min,5©1994-2008ChinaAcademicJournalElectronicPublishingHouse.Allrightsreserved.[Si]CASRH,,CAS,LCAKELCULC,CASRH4(1)[O],LF,[O],[Si](2)LF,,,[Si](3)CASRH,,LCAKELCULC,CASRH:[1]TakeuchiS.SteelmakingProcessTechnologiesforCleanlinessandInclusionControlofUltraLowCarbonSteel[A].The182thand183thNishiyamaMemorialTechnologicalConfer2ence[C].Tokyo:ISIJ,2005.65288.[2]BurnsMT,SchadeJ.RecentDevelopmentsinMeasuringSteelCleanlinessatArmcoSteelCompany[A].1991SteelmakingCon2ferenceProceedings[C].L.P.:ISS,1991.5132523.[3]BannenbergN,SchutzC2H.ProcessRoutesfortheProduc2tionifIFSteelsandSomeOtherHighQualitySteelGradesWithRegardtoSteelCleanliness[A].CSM2VDEhSteelmak2ingTechnologySemi