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节约型钢铁材料制造过程revisedCost-savingsteelsandtheirmanufacturingprocessesWANGGuo-dong,LIUXiang-hua,WUDi(TheStateKeyLaboratoryofRolling&Automation(NortheasternUniversity),Shenyang,110004,China)Abstract:Resources-conservingmanufacturingisbecominganimportanttendencyinmaterialsproduction.Cost-savingsteelsandtheirmanufacturingprocesseswereexplored,duringwhichtheviewpointinenergysavingandsources-savingtorealizecost-savingproductionwasdiscussed.Therewereaboutfouraspectsindetail:designandproductiontechnologyforcost-savingsteels,cost-savingproductionprocesses,cost-savingproductionlifecycleandenvironment-friendlyproduction.Keywords:Cost-savingsteels,Manufacturingprocess,Environment-friendlyproductionChinahasissuedthemedium-termandlong-termdevelopmentplanningcompendium,whichisaguidingdocumentforthedevelopmentofscienceandtechnology.Ithasbeenpointedoutthatmanufacturingprocessfornewgenerationsteelsneedstobedeveloped,andthreemajorfunctionsneedtoberealizedduringtheproduction,includingrawironandsteelsupplying,energyanddisposingwastetransferring.Torealize cost-savingmanufacturingprocessesofnewgenerationsteelswillpromotecontinuoussocio-economicdevelopmentofourcountry.1.Designingandmanufacturingprocessforcost-savingsteelsIronandsteelmaterialsarewidelyusedfortworeasons.Ontheonehand,theyareinexpensiveandinlargescaleproduction,ontheotherhand,theymaypossessdifferentstrengthsinalargerangebyapplyingsuitablecontrolledrollingandcontrolledcooling,ortheso-calledTMCP.Thechiefgoalofcontrolledrollingistocontrolthestateoftheaustenite,whilecontrolledcoolingistocontrolthephasetransformationofdeformedausteniteandtorefineferritegrain,orimprovethesteelperformancebycontrollingthephaseproportiontoformcomplexphasestructure.Intensivelyutilizingthecharacteristicsofphasetransformationinironandsteelmaterialsplaysanimportantroleintappingthematerialspotentialandrealizingcost-savingmanufacturing[1].1.1Developmentof400-500MPagradestripsNewgenerationironandsteelmaterialsaredevelopedtosavemoreresources.Thatistoaddnoneorlessalloying/microalloyingelementstoproducethesteelswithhighperformance.Forexample,thestrengthandtoughnessof200MPagradecarbonsteelcanreachthesamelevelof400MPasteelsbyimprovingandoptimizingprocessingparameters. Accordingtotheresearchonstaticrecrystallizationoflowcarbonsteel,deformedaustenitedoesnotrecrystallizewhentheinter-passtimeislessthan5safterhotdeformationatthedeformationtemperaturebetween850℃and900℃.Consideringthetime,controlledcoolingcarriedoutinthenon-recrystallizationzoneinseveralminutesafterdeformationisthekeytorefinethegrainsofC-MnandlowC-Mnsteels.Therefore,thecoolingafterrolling(includinglaminarcurrentcoolingdeviceofhighdensityandlargeflux,curlingatlowtemperature)playsanimportantroleinthedevelopmentofcost-savingstrip.Accordingtothethoughtsabove,byoptimizingrollingschedules,checkingtherollingload,loweringfinishingrollingtemperatureto800℃,increasingcoolingratetobehigherthan30℃/s,lowcarbonsteelscanpossessthesameover-allpropertiesas400MPagradesteels.Itsstructureanalysesindicatethattheincreasingofstrengthisduetonotonlygrainrefinement,butalsotheformationofbainite.Owningtothecombinedeffectofrefinementandtransformation,itreachestheneedofcustomerwiththeyieldingstrengthexceeding400MPa,thetensilestrengthexceeding540MPa,elongationpercentageexceeding27%.Expensivealloyingelementshavebeensavedtosubstitutemicroalloysteels,andcost-savingsteelmanufacturingprocessisrealized.1.2Theexploitationofcost-saving400－500MPagradewireWirerollingbelongstohigh-speedrollingprocess,thedeformationheatleadstohighertemperatureforthework-piece,thefinishing temperaturecanreachto1000℃,solowtemperaturefinishingrollingcannotbeexecutedasinplaterolling.Inwirerolling,thetotalreductionishigh,rollingspeedishigh,directionofdeformationvariescontinuouslyandinter-passtimeisshort.Suchacontinuouslargedeformationispronetorealizestrainaccumulationandleadstohardeningtheaustenite.Inallusiontothefeatureofwirerolling,inordertorealizedeformationhardening,alargestraincontinuousaccumulationdeformationisusedinwirerolling;cross-waterquickcoolingbeginsimmediatelyafterrolling,andwaterspraycoolingisusedinordertogethighcoolingrateandnecessaryfinalcoolingtemperaturetolimitrecrystallizationofausteniteandkeepthehardeningstateofaustenite.Byfinishingcoolingatapropertemperatureandcontrollingphasetransformationprocess,thequenchingorganizationispreventedtooccur.Accordingtosuchatechnicalroute,byusingC0.22-0.25%－Si0.33-0.42%－Mn0.7-0.8%(massfraction)asmaterial,HRB400MPafine-grainedbarwireisproduced,thestableandlarge-scaleindustrialproductionhasbeenrealized(Fig.1)[3].Fig.1Routeofreductionwireproductiontechnology1.3Theexploitationofcost-saving400－500MPagradebarsScrewthreadsteelisasteelproductwiththelargestproductionin China,andhasadrasticcompetingmarket.400MPagradehotstripfine-grainedbarHRBisusuallyaddeddefiniteamountofmicroalloyelementssuchasNb,V,andTionthebaseof20MnSi,whichhasincreasedthecostofproductionandconsumeplentyofmicroalloyelements.InordertouseHRB335(viz.20MNSi,IIgradesteelbar)asthebasicmaterial,theoverallstandardquantityIIIgradesteelbar(HRB400)isobtainedbycontrollingproductionprocessonthebasisofnoaddedmicroalloyelement.Anewtechnicalthoughtofconventionalhightemperaturecontinuousrolling+ultra-fastcoolingaftercooling+stopcoolingatpropertemperatureisbroughtforwardforbarsupersteelproduction.Thisoptimizedprocesssystemfullyutilizeshightemperature,highspeed,intensivedeforminghardeningandphase-changeduringthecourseoffine-grainedaustenitecooling,tocontrolmaterialperformance.Notonlymechanicalpropertycanreachnationalstandards,butalsoweldingperformanceandageingperformancecanalsosatisfytherequirements.Thistechnologyhasbeenappliedtoapasselofsteelmillsandacquiresverygoodeffects.1.4Theexploitationofcost-savingpipelinesteelsPipelinesteelisthemostimportantsteelforenergygeneration,fromtheendofthe80son,pipelinesteelwasexploitedinChina,whichhasreachedX80strengthgradeandcanbesuppliedasdifferentspecificationsorvarietiessuchashotstrips,mediumplates.Inordertoassurethemechanicalproperties,TMCPtechniquesareemployedinpipelinesteels exceedingX70toformacicularferritestructure,granularbainitestructureandlowerbainitestructureaccordingtodifferentrequirements.Onthedesignofelements,Moisusedasalloyelementsextensively,butthepriceofMoisveryhigh,sopeoplestarttosearchfornewalloyelementdesignandcorrespondingproductiontechnology.NbCorporationofBrazilexploitednewseriesofmicroalloyelementsbyusingNbinsteadofpreciousMotoproducepipelinesteels.ThedesignofhighNbelementseries(includingNbabout0.1%)andcorrespondingHTP(HighTemperatureProcessing)manufacturingtechniques[5]weredevelopedwithinternationalcooperationfromseveraldifferentnationalmills,andX80gradepipelinesteelhasbeenproducedsofar..1.5Exploithighstrengthsteelforvehiclebytransformationstrengthenandcoolingroutecontrol（AHHS）Transformationstrengtheningmainlyresultsfromtherefinedferritetoincreaseyieldstrength.Martensiteandbainitehardphasesdistributedonthematrixofferritearemainlyusedforimprovingtensilestrength,whichcandecreaseyieldratioofmaterial.TheStateKeyLabofRollingandAutomation,NortheasternUniversity(RAL)establishasetofcontrolcoolingexperimentalfacilityincludingultra-fastcooling(UFC）andacceleratingcooling(ACC),asshowninFig.2.UFCcanacquirecoolingratemorethan400℃/sfora4mmthickplate.Nb-bearingmicroalloysteelwhosechemicalconstitutionis0.14C-1.47Mn-0.26Si-0.024Nb-0.012Als(masspercent)hasbeenusedin trialsforstudyingtheeffectsoftransformationstrengthening.Fig.2LayoutofexperimentalmillandUFCequipmentFig.3StructureandmechanicalpropertyofsteelWiththedecreasingoftemperatureduringthetransformationfromaustenitetoferrite,thetransformationproductsaredifferent.Therefore,wecanobtaindifferenttransformationproductswithdifferentperformancesbycontrollingthecoolingrouteoftransformation.Tomakeuseofthefeature,differentmicrostructuresandperformanceofsteelsareobtainedbyadjustingUFCandACC,coolingrateofdifferentparts,theinter-passtimeonACCandthetemperatureofUFCsubsequently.Fig.3showsthemechanicalpropertyandcorrespondingphasecompositionofsteelsbydifferentcoolingprocessesintheexperiment.Itisobviousthatthecontrolofthecoolingprocessesprovideapowerfulmeanstoobtaindifferentperformanceofsteelsandthatitcanplayanimportantroleonthereductionofsteels.2.NewprocessofReductionproduction2.1DPandTRIPsteelsproducedthroughTSCRThestabilityduringrollingandcoolingisanimportantcharacteristicforTSCRprocess.Inotherwords,thetemperatureandcrossdimensionsonthelineofrollingdonotchangewithtime.Then,thedisturbancewhichisbroughtaboutbychangingspeedrollingintheproductionofhotstripcanbeavoided,andtheprocesswindowofrolling andcoolingisenlargedwithoutalloyingagentduringthestablecontrollingofcoolingroute.AnexploratoryexperimentaboutC-MnDPsteelwasinvestigatedonthelineofCSPinBaotouIron&SteelGroupCo..ThemechanicalpropertiesofthefirstDPsteelswhichareindustriallyproducedandF+PsteelswiththesamecomponentsmanufacturedbyconventionalprocessareshowninTable1.ItcanbeseenthatascomparedwiththeF/Psteel,theiryieldstrengthisalmostsame,butthetensilestrengthofDPsteelisobviouslyimproved,soyieldtotensileratioisreducedgreatly.FurthermorethestripcanownexcellentuniformityofstructureandpropertyduetowellstabilityofCSPcontrolling.ThemechanicalpropertyoftestedsteelisequivalenttoDP540hotrollingdualphasesteel.Table1MechanicalpropertiesofthetestDPsteelandtheconventionalF+PsteelTestpiecenumberTypeofsteelthicknesswidthRp0.2RmA50Rp0.2/Rmn mmmmMPaMPa%1#TestedDP6.01500365545310.670.212#TestedDP5.01500 375570290.660.213#CommonF+Psteel5.01500370*450430.82—2.2TSCRshortrouteforproducingsiliconsteelMnSorAlNisusedfortheinhibitorinthetraditionalproductionprocessoforientationsiliconsteel,whichrestrainsthegrowthofdisadvantageousorientationrecrystallizedgrains,andpromotesthegrowthofadvantageousorientedgrains.Inordertoformtheneededinhibitor,traditionalprocessmustreheatmaterialsintoveryhightemperature(1350-1400℃),however,whichnotonlyconsumesmore energy,butalsoincreasesthequantityofemittedCO2andthedifficultyofprocessing.Inrecentyears,thenewproductionprocessofsiliconsteelhasbeeninventedcontinually.Recentlycontinuouscastingprocessofslabsattainedgreatpromotion.Chinahashadmorethantenshortroutelines.Someforeignfactoriesexploitedthenewcontinuouscastingandtandemrollingprocessforproducingorientedsiliconsteels.TSCRprocessisthatpouringthemoltensteel(MnSandAlNnaturallycompletelydissolveinthemoltensteel)intothemold,thentheslabisdirectlyputintunnelingfurnaceforsoakingandheatingpreservation,finallytheslabisloadedtothemillsforrolling.Becausethebilletdonotappearthestepofferritetransformationanddonotdeformbeforeloadingtothemills,somostofMnSandAlNstillmaintainthedissolvedstate,whichsuper-finelyprecipitateduringthesubsequentfinishingrolling.Theseprecipitatescanbeusedforinhibitors.Atthesametime,takingadvantageofNH3forextractingnitrogentosupplyapartofinhibitorsundercomparativelylowtemperature(forexample900℃)afterthesubsequentPRanddecarbonization.BecausetheprocessthatTSCRrollorientationsiliconsteelneednoreheatintohightemperature,whichreducesenergyconsumptiongreatlyanddecreasesthebuildingdifficultyofproductionandfacilities,soTSCRisapromisingnewprocessfororientationsilicon’scost-savingproduction.2.3Flexibleproductionprocess Modernizedlargeproductionshouldbelarge-scalecustomization,namelytheproductionislarge-scaleatthesametimeproductscansatisfythedemandofconsumer’sspecialrequriements.Therefore,howtoenhancetheproductionflexibilityisveryimportant.Changingtheconditionofrollingandcooling,especiallycontrollingthecoolpathcanrefinethegraininwiderangeandinfluencethemicrostructure,leadingtodifferentpropertiestosatisfydifferentrequirements.Wecantakefulladvantageofittoresearchtheso-calledflexiblerollingtechnology.Thetechnologyjustisthatusingthesamematerialtoproducesteelwithdifferentstrengths,structureandpropertiesthroughthecontroledrollingandcooling.Thusthesecanwellsimplifytheoperatingofsteel-smeltingandcontinuouscastprocess,begoodforproduction’sorganizationandscheduling,andmoreoverestablishthebasicforachievingthelarge-scalecustomizationofrollingproduction.2.4Theon-linethermaltreatmentprocessforplateGenerallyspeaking,thethermaltreatmentisoperatedinoff-linesituationusingnormalizingfurnaceormodifiedfurnace,thereforeitneedsreheating.Beingdifferentfromtraditionaloff-linethermaltreatment,JFEFuSanPlateCompanyinstalledtheon-linethermaltreatmentequipmentbehindleveler,whichcooperatedwiththenewsuper-coolingfacilitySuper-OLAC(Fig.4),inordertohardenandtempertheplateandrealizetheproductionofcost-savinghighqualitysteel plate.Thisequipmentapplysafewofhighfrequencyelectricalsourcestoheatbyinductancecoilandcouldon-lineheattheplatewithmaximalwidth4.5m.Whenthecoilhascurrent,itmakestheplateoccurinducedcurrentandemitheat.Theheattransferrateisabout105-107w/㎡.Theheatcapabilityofthisequipmentisequivalentto100timesofgasheating.Becausetheon-linethermaltreatmentequipmentappliesthenewon-linetreatmentprocess,ithassomenewcharacteristicsascomparedwithtraditionaloff-linethermaltreatment,includingthat1)thermaltreatmentprocessiscompletedatthesamestepwithrollingandcoolingprocess,shortdeliverytime,andhighproduction;2)bycooperatingwithSuper-OLAC,itcancontrolphasetransformationandprecipitation,leadingtogeneratenewstructureandpropertyandfindinganewmethodtoimprovethesteel’sproperty.Fig.4Newproductionofon–lineheattreatment2.5NewformingprocessofhigherstrengthofautomotivesteelsFig.5ProcessofheattreatmentstrengtheningTheautomotivesteelsarecontinuallydevelopedtowardshighstrength.Inrecentyears,thestrengthofAHSS,whichincludesDP,TRIPandother steels,hasalreadyarrivedat1200MPagrade.Alongwiththeimprovementofstrength,therearemoreandmoredifficultiesinformingproperty,productionandapplicationofsteels,especiallyinshape.Therefore,workhasbeguntoexploreotherwaystoimprovethestrengthofsteels.Forexample,inrecentyears,theprocessofstrengtheningheattreatmentisarapidlydevelopingnewtechnology[11]。Fig.5showsthemainformofstrengtheningheattreatment.Theycangreatlyreducethedifficultyofprocessingdeformation.Afterprocessingshape,productionwillbeindiesorspecialquenchingdevicesforheattreatment.Thestrengthofthematerialneedstoberaisedtothelevelbyrequest.Currently,EuropeandJapanhaveappliedtheprocessofstrengtheningheattreatmentandtheyproducedofcomponentssuchasroofstrengtheningpiecesofautomotiveinindustrialtrails.Atpresentthehotformingaccessorieshavebeendevelopedandused,andthetensilestrengthof1500-2000MPacanbeobtained.3.ReductionsthroughoutthelifecycleofproductsSteelmaterialsaremanufacturedtobesteelproducts.Itistobetransportedtotheusersforfurtherprocessingoffinalproducts.Then,theproductsaretobewastedisposalafterbeingused.Throughoutthelifecycleofsteelmaterials,thereareacertainnumberofCO2,pollutantsandwaste.Steelmanufactories,shouldtakeintoaccountthatthemanufacturingprocessesmeetthereductionandgreennotonlyintheproducingprocess,butalsointhefollow-upprocessing.Wehadbettermeettheneedsofhumancivilizationforthesmallestenvironmentalload. Thefollowingareafewexamplesofachievingreductionsthroughouttheentirelifecycleofsteelmaterials.3.1TRIPsteel,DPsteelusedforhighstrengthfastenerThegeneralproductprocessofhighstrengthfastenerisshowninFig.6.Afterannealinganddrawingprocess,thehot-rolledwiresaremachineprocessed(includingupsettingandprocessingthewhorls).Thenthethermallevelingisproceeded.Thestocksareheat-treatedtwice,whichneedsmorelaborandequipmentandincreasedthecost.Tosolvethisproblem,anewtypeDPsteelusedforhighstrengthfastenerwasdevelopedbyCORUS[12],thechemicalcompositionofwhichisC0.08%-Si1.0%-Mn1.7%-Cr0.016%(byweight).Throughthisthesimplifyingofprocessisrealized.Fig.6ProcessoffastenerproduceTheRALinNEUalsohasdevelopedaTRIPsteelusedforhighstrengthfastener,forwhichthethermalprocessisnotnecessaryeither.3.2LPsteelIftheopeningoftherollerschangescontinuouslyduringrollingprocesstomakethethicknessofplateschangecontinuouslyatthelength direction,theLPsteelplatesareproduced[14].BecausetheLPsteelcanbeusedtooptimizethecross-sectiondesignsofbridgesandshipsthroughchangingthethicknessofbeamsaccordingtotheload,LPsteelisakindofcost-savingsteel.Figs.7andfig8issamplesofLPsteel’sapplicationsinthebridgesandships.Fig.7UsageofLPsteelinbridgesFig.8UsageofLPsteelinships3.3MaterialsusedinlargeinnerheatweldingWeldingisanimportantpropertyforsteelusedinships,bridgesandvessels.Thelargeinnerheatwieldingthatcanlargelyimprovethemanufactureefficiencyisimportanttotheseindustries.TheinitialideaisthattheTiNthathashighmeltingpointisusedtopintheaustenitegrainboundary.ButduringthelargeinnerheatwieldingthetemperatureofHAZcanreach1400℃.AtthistemperaturesomeTiNparticlesdonothavetheabilitiestopinthegrainboundarybecausetheyaresolvedoragglomerated.Sotheseyears,MgandCa,whichhasstrongaffinitywithSandO,isaddedtothemoltensteelbysomeresearchersabroadtoform sameheat-stableparticlesthatareneithersolvednorpronetogrowingup.Theseparticles,thesizesofwhicharetensorhundredsnm,arethinanduniform.Andtheyarenucleusinthesolidifyprocess,whichcanrefinethesolidtextures.Furthermore,thefineparticlescanprohibitthegraingrowthinHAZduringwelding[15].Thegrowthoftwokindsofsteelat1400℃,whichcontainTiNoroxideandsulfideofMgandCaparticles,areshowninFig.9.Itcanbeconcludedthatgrainsofsteelthatcontainoxideandsulfideparticlesdidnotgrowandshowedgoodheatendurance.Fig.9Growthofgrainat1400℃4.Environment-friendlyproductsTheapplicationofnewgenerationalironandsteelmaterialsshouldmeettherequirementsoftheenvironmentalprotection,whichsatisfythesocialdemandswiththeleastpressuretotheenvironment.Then,manufactureofenvironment-friendlyproductsshouldbetheresponsibilityforthematerialprocessingindustries.TakingCrionsandPbasexamples,theseriousproblemsthattheironandsteelindustriesarefacing,andtheprogressthathasbeenmadeareexplainedinthissection.4.1Galvanizedandcolor-coatedsheetswithoutchromeions Inordertoimprovetheperformanceofresistancetowhiterustingandthepaintingperformanceforpaintedcoatsteelsheets,thevariouspaintedcoatsteelsheetswerepreviouslypassivatedwithCrions.However,Crionswhichareincludedintheelectrolyticandproductsrelatingtopassivationtreatmentcandoharmtotheenvironmentduringitsusingprocessandalsoafterthedisposal.So,adraftabout“Apolicywithrespondtothevehiclewaste”,inwhichCrionswasforbidden,wasbroughtforwardbyEuropeanParliamentin1997;subsequently,theuseofmaterialsincludingtheaboveharmfulsubstanceswasalsoforbiddenintheelectronicproductsaccordingtothelaw“WEEE”and“RoHS”abouttheelectronicandhomeappliance,whichwillbecarriedoutin2007.Inourcountry,thesamestrictrequestwasalsoputforwardandlegislatedatthesametime.Toimprovetheformabilityofgalvanizedsheetusedforvehicle,areallythininorganicMn-Plubricatingfilm(100mg/m2)isinvestigatedandproduced.Accordingtotheexperiment,theformabilityissurelyimprovedwiththeuseofthisfilmwhichdoesnotdoanyharmtotheprocessofvehicleproduction,andthecorrosionresistantperformanceisstillgoodafterpainting.Zn-Nialloyedcoatwithathicknessof4umisdevelopedbyKawasakiJapanRailsystem,whichpossessesperformancesofaesthetic、formability(self-lubrication)、corrosionresistance[16].4.2Unleadedsteelusedforfueltank Pb-8%Sncoatedsteelsheetsarewidelyusedundertheconditionsofserverecorrosion.However,Pbisapparentlyforbiddenforitsharmness,andseveralnewenvironment-friendlyproductshavebeendevelopedforfueltanks[17]intheseyears.Theyinclude1)hot-dipSn-Znalloyedsteelsheet;2)hot-dipAl-Znalloyedsteelsheet;3)GI-doubleNiplate;4)organiccoatingsteelsheet.Allofthemarewidelyusedfortheirgoodinnercorrosionresistance,outercorrosionresistance,goodformabilityandweldability.Reference[1]Xiaozhijunfu,ControlledRollingandControlledcooling-DevelopmentofRollingTechnologyforImprovingSteelProperties,MetallurgicalIndustryPublishingCompany,2002,Beijing.[2]WangGDetal,TheindustrialrollingtrialsofSuper-SS400，IronandSteel，36（2001），No.5，39-43[3]ZhaoDWetal，Theexperimentsandindustrializationofhotrolledsupersteelwires,IronandSteel，40（2005）,No.12.[4]WuDi，TheExploitationofLowCostHigh-poweredHRB400、HRB500ribbedbar,tobepublished[5]KlausHulka,ProductionExperienceofLowCarbonHSLASteelswithNbContentfrom0.06%to0.10%,Micro-alloyingTechnology,Vol.4(2004),No.4,1-13 [6]LiuYan-chunandetc.,ExperimentresearchonDevelopmentofHighStrengthHotRolledMultiPhaseStripSteelwithUltrafastCoolingTechnologyEmployed,tobepublished[7]LeDe-gangandetc.,Developmenton540MPaHotRolledDualPhasesteelonCSPProductLineinBaotouSteel,2006’InternationalConferenceonThinSlabCastingandRolling,2006,Guangzhou[8]KlausGuntheretc.,RecentDevelopmentonManufacturingTechnologyofOrientationelectricsteel,WorldIronandSteel,2005,No.5,1-8[9]LiuXiang-huaetc.,FlexibleRollingTechnologyandtheTrendinDevelopment，ChineseConferenceonNonferrousMetalsProcessing,2005,Sanya[10]FUJIBAYASHIAkio,etal,JFESteel’sAdvancedManufacturingTechnologiesofLeadingHighPerformanceSteelPlates,JFETECHNICALREPORT,2004,No.5,8–12[11]NobusatoKojima,StrengtheningbyHeatTreatmentforSteelSheetParts,JSTP,Vol.46(2005),No.534,595-599[12]A.J.TROWSDALE&S.B.PRITCHARD,DUALPHASESTEEL-HIGHSTRENGTHFASTENERSWITHOUTHEATTREATMENT,CORUSCONSTRUCTION&INDUSTRIAL,UK [13]LiZhuangetc.,ResearchonHeattreatment-freeHighStrengthLowYieldRatioRivetedSteel,IronandSteel,tobepublished[14]OsamuTanigawa,etal,DevelopmentofHighPerformanceSteelPlatesinTermsofReliabilityandEconomyofSteelStructure,KawasakiSteelTechnicalReport,32(2000)3,198-204[15]PlateSalesDivision,SuperHighHAZToughnessTechnologywithFineMicrostructureImpartedbyFineParticles,NipponSteelTechnicalReport,2002(376):82[16]HiroshiKANAI,etal,Electro-andHot-dipGalvanizedSteelSheetsHavingCr-freeTreatmentLayeronthesurfaceandCr-freePrepaintedElectrogalvanizedSteelSheets,NSCTECHNICALREPORT,No.371(1999),43-461[17]MasaoKUROSAKI,etal,Pb-freeCoatedSteelSheetsforFuelTanks,NIPPONSTEELTECHNICALREPORT,No.88July2003,51-56NewRouteConventionalRoutePlate Head&ThreadDrawingRodrollingPlateDescale /CleanQ&THead&ThreadAnnealingDrawingRodrolling Inductiveheater500mm500mm4500mmMill ACCBackUFCHeadUFC
