简介：Non-metallicinclusionisthemainreasonforthepresenceofsurfacedefectsincold-rolledsteelstrip.Inthisstudy,thecomposition,morphology,andsizeofthenon-metallicinclusioninhot-rolled304stainlesssteelstripsareanalyzed.Cold-rolled304stainlesssteelstripswithdifferentcold-rollingreductionhavebeenprepared,andthemorphologyandsizeofinclusioninthesecold-rolledstripsarealsoanalyzed.Furthermore,thedeformationbehaviorofanon-metallicinclusionduringthecold-rollingprocessisstudied.TheresultsshowthatCaO-SiO2-MgO-Al2O3,akindofbrittlecompoundoxide,isthemaintypeofinclusioninhot-rolled304stainlesssteelstrips.Duringthecold-rollingprocess,ductiledeformationofthistypeofinclusionisnotobvious,wherelargeinclusionsarecrushed,andtheaveragesizeofinclusionsincold-rolledstripsdecreasedwhilethecold-rollingreductionincreased.

简介：Withthecontinuousimprovementofproductqualityandfunction,thequalitycontrolofmoldsteelisbecomingincreasinglystricter.Argonprotectionisessentialforensuringcastingqualityduringingotcasting.Thedevelopmentofargonprotectioniningotcastingandtheproductionprocessofenclosedargonprotectionin40tlineisdiscussed,withparticularfocusgiventhefactorsaffectingtheflowofoxygenintheargonprotectioncoverarediscussed.Theinfluenceofsomerelatedfactorsontheoxygencontentisanalyzed.Onthebasisoftheonlinemeasurementsoftheoxygencontent,theoptimizedoperationalapproachesforimprovingtheeffectofargonprotectionaredeveloped.Thiscandecreasetheliquidsteelviasecondaryoxidation,andimprovethequalityoftheingots.

简介：Thedynamicandstaticrecrystallizationbehaviorsoftwinrollcastlowcarbonsteelstripwereinvestigatedwithanattempttoprovideguidingdeformationparametersfortheonlinehotrolling.Inordertoinvestigatedynamicrecrystallizationbehavior,ascaststripwasreheatedandsoakedwithaustenitegrainsizesimilartothewidthleveloftheascastcolumnarstructure.Tensiletestwasusedandthedeformationtemperatureisintherangeof900℃to1100℃andstrainratesare0.01s-1,0.1s-1,1s-1.Theactivationenergyandstressexponentweredeterminedas306kJ/moland4.69respectively.Theratioofcriticalstraintothepeakstrainis0.65,andthatofcriticalstresstothepeakstressis0.92.ThedependenceofthepeakstrainontheinitialgrainsizeandZener-HollomonparametersZisεp=9.1×10-4×D00.48Z0.13.Thekineticsofthedynamicrecrystallizationandrecrystallizedgrainsizewaspredictedusingmodelspublished.Theascastcoarseausteniteweredramaticallyrefinedaftercompletedynamicrecrystallization.Forstaticrecrystallization,thetensiletestwascarriedoutonGleeble-3500thermo-mechanicalsimulator.Thedeformationtemperatureisintherangeof800℃to1200℃withstrainrate0.01s-1to1s-1.Theprestrainisfixedat0.04to0.12andtheinter-hitdelaytimevariesfrom1sto3000s.TheactivationenergyandAvramiexponentofstaticrecrystallizationweredeterminedas241kJ/moland0.54respectively.Akineticsmodelwasproposedtodescribethestaticrecrystallizationkinetics.Thepredictedresultswereingoodagreementwiththeexperimentalresults.

简介：ThecorrosionbehaviorofaweatheringsteelSPA-Candtwoacidresistancesteels(S-TEN1andND)insulfuricacidsolutionwasinvestigatedbyusingpotentiodynamicpolarizationandweightlossmeasurementtechniques.Bothpotentiodynamicpolarizationandweightlossmeasurementtestsindicatedthatcorrosionresistanceofthesethreealloysteelswasasfollows:ND≈S-TEN1>SPA-C.Surfaceanalysisofthecorrodedsamplesconductedaftertheimmersiontestindicatedthattwolayerswereformedonthesubstrates,withtheouterlayercomprisingFeSO_4·H_2Oandtheinnerlayermainlycomprisingironoxides.TheadditionofCu,Cr,andSbrefinedthecorrosionproductsandimprovedtheadhesionabilitybetweentherustlayerandthesubstrate.

简介：Ore-cokemixedchargingisapotentialtechniqueforoptimizingthechargingpattern.Recently,thechargingofsmall-sizedcoke(nutcoke)withtheferrousburdenlayerhasbeenappliedtoreducerawmaterialusageanddecreasecosts.Variousstudiesindicatethatmixingnutcokewithferrousburdencanenhancethereductionkinetics,improvethesofteningandmeltingproperties,andhaveapositiveeffectonthepermeability.Althoughmixedcharging,especiallytheadditionofnutcoketotheburdenlayer,hasbeenusedintheindustryforvariousreasons,themechanismsandsideeffectsforusingnutcokearenotwellunderstood,andthemixingratioremainslimitedinactualblastfurnaceoperation.High-temperatureexperimentalstudieswereconductedtoincreasetheunderstandingofthecomplexprocessofreduction,softeningandmeltingproperties,andpermeabilityinablastfurnacewhenmixingnutcokewithanorelayer.Theeffectofthenutcokemixingratioandnutcokesizewasinvestigatedundervariousreducingconditions.Todescribethereductionprocessesofburdenmaterials,numerousexperimentswereinterruptedatdifferentstagesofthereduction,andthecollectedmaterialswereexaminedbyusingimageanalysis.Thereductiondegreeofmixedcharging(ironoremixingwithnutcoke)wasimprovedwhenusingnutcokeatthetemperaturesof800℃andabove.Thereactionrateofore-nutcokemixedchargingwashigherthanthatofstandardchargingwithouttheuseofnutcoke.

简介：Thermalbehaviorofthesolidifyingshellincontinuouscastingmoldisveryimportanttofinalsteelproducts.Inthepresentwork,onetwo-dimensiontransientthermal-mechanicalfiniteelementmodelwasdevelopedtosimulatethethermalbehaviorofperitecticsteelsolidifyinginslabcontinuouscastingmoldbyusingthesequentialcouplingmethod.Inthismodel,thesteelphysicalpropertiesathightemperaturewasgottenfromthemicro-segregationmodelwithδ/γtransformationinmushyzone,andtheheatfluxwasobtainedaccordingtothedisplacementbetweenthesurfaceofsolidifyingshellandthehotfaceofmoldassolidificationcontraction,theliquid-solidstructureanddistributionofmoldflux,andthetemperaturedistributionofslabsurfaceandmoldhotface,inaddition,therate-dependentelastic-viscoplasticconstitutiveequationwasappliedtoaccountfortheevolutionofshellstressinthemold.Withthismodel,thevariationcharacteristicsofsurfacetemperature,heatflux,andgrowthofthesolidifyingshellcorner,aswellasthethicknessdistributionoftheliquidflux,solidifiedflux,airgapandthecorrespondingthermalresistanceweredescribed.

简介：

简介：InfluenceofdifferentcoolingratesonthemicrostructureandtheprecipitationbehaviorofNb-TimicroalloyedsteelwasinvestigatedbyCSLM,OM,SEMandEDS.Theresultsshowthattheprecipitationprocessofcarbonitridescanbein-situobservedbyCSLM,andwiththeincreaseofthecoolingrate,thedistributionofprecipitateschangesfromalongtheausteniticgrainboundariestowithinthegrains.Withtheincreaseofthecoolingrate,theproeutectoidferriticfilmbecomessmallerandsmallerandthendisappears,andtheoriginalausteniticgrainsbecomefinerandfiner.Inordertoobtainnon-filmlikeproeutectoidferritesornon-chainlikeprecipitatesalongtheausteniticgrainboundariesandfinerausteniticgrains,thecoolingrateshouldbeatleast5℃/s.

简介：Thetensilebehaviorandpropertiesofcoldformedlow-carbonmicroalloyedsteelwithitsmicrostructureofallferriteandpearlite(F+P)wereinvestigated.Bendingandflatteningdeformationswerecarriedoutinthelaboratoryonhot-rolledsheetsinordertosimulatethecoldformingprocessofsteelsheetsduringpipefabricationandsamplingofhighfrequencystraightbeadweldingpipes.Acomparisonofthetensilebehaviorandpropertiesofthematerialmadebeforeandaftercoldformingindicatesthatcolddeformationaltersthetensilebehaviorandpropertiesofthematerialtoacertaindegreedependingonthemannerofthecolddeformationandthedegree.TheresearchontheBauschingereffectindicatesthatforthesteelsinvestigated,whentheplasticstrainissmall,thebackstressincreasesrapidlywiththeincreaseoftheplasticstrainandthenrapidlytendstosaturation.ThefiniteelementanalysisindicatesthatthechangeinthepropertiesofthesteelsheetsduetocoldformingisaresultoftheBauschingereffectandworkhardening.Themechanismofthechangeinthepropertiesisalsogiveninthisstudy.

简介：Themorphologyandtheevolutionofδ-ferriteexistinginB410Dslabs,hot-rolledplates,annealedplatesandquenchedplateswerestudiedthroughmetallographicobservation.Resultsshowthatδ-ferriteformsduringthesolidificationprocessandthatiteasilygrowsandincreasesinquantityduringhightemperatureannealing.Band-shapedδ-ferriteinhotrolledplatesisdifficulttobeeliminatedbyconventionalheattreatmentandhardtorecrystallize.

简介：UnderstandingthecomplexphenomenainBFhearthisessentialtoincreasefurnaceproductivityandtoextendfurnacecampaign.Wehavedevelopedseveralcontinuum-basedmathematical/numericalmodelstosimulatethemulti-phaseflow,heattransferandchemicalreactionsintheBFhearth.Thesemodelshavegeneratedanimprovedinsightonthemechanismsforliquiddrainageefficiency,liningerosionandwallprotectioninBFhearthunderoperationalconditions.Thecurrentpapergivesanoverviewofthesestudiesinthreeaspects:Gasflowandpressureontheliquidsurface,andtheireffectonthedrainagecharacteristics;TheflowandtemperaturedistributionsofliquidironinBFhearth,andthetemperaturedistributionintherefractories;Finally,titaniumbehaviorsduetotitaniainjectiontoformTi(C,N)-richscaffoldonthehearthsurface,toprotectthehearthfromerosion.

简介：Thecriticaltransformationtemperatures,Ac1andAc3,ofahot-rolledlow-carbontitaniummicroalloyedsteelweredeterminedasapartofanexaminationofitsphase-transformationbehavior.Austenitedecompositionduringthecontinuouscoolingofthetitaniummicroalloyedsteelwasstudiedbyheatingitto1250℃,coolingitto880℃,holdingfor2s,andthencoolingittoroomtemperatureatdifferentcoolingrates.Thetransformationkinetics(CCTcurve)wascharacterizedaswell.

简介：TheeffectofdeformationconditionsondynamicrecrystallizationbehaviorofNb,V,Timicroalloyedhigh-strengthstructuralsteelwasinvestigatedviahigh-temperaturesinglepassreductiontestsonaMMS-300thermomechanicalsimulator,withmathematicalmodelsestablishedforflowstressduringhotdeformation.Theresultsshowthatthedeformationresistancedecreaseswiththeincreaseoftemperatureandisinpowerfunctionrelationshipwiththetemperature.Meanwhile,itincreaseswiththeincreaseofstrainrateandisinlog-logrelationshipwiththestrainrate.Thedynamicrecrystallizationactivationenergyoftestedsteelwasdeterminedtobeabout329.55kJ/mol,295.31kJ/molatpeakandsteadystates.Thepredictionmodelsdevelopedforflowstressindicatedthattheyareingoodagreementwithexperimentalresults.

简介：Thehot-deformationbehaviorofFe-Mn-Ctwinninginducedplasticity(TWIP)steelwasinvestigatedbyconductinghotcompressiontestswithinarecommendedhotrollingtemperaturerangeatvariousstrainrates.Flowresistancecurvesduringhot-deformationwereobtained,andstrainratesensitivitiesandactivationenergiesforplasticdeformationwerecalculatedusingthepowerlaw.ItisfoundthattheadditionofAlandSiclearlyincreasesthepeakstressesforthepresentalloys,especiallyat950℃.ButMnhasaminoreffectonthestress-straincurvesandactivationenergywhenitscontentvariesfrom15mass%to22mass%forthepresentalloys.

简介：InordertosuppressthesurfacecrackinginducedbyCuduringreheatingandhotrollingprocess,Cuenrichmentanditsmigrationatthesteel-scaleinterfacewasinvestigatedduringheatingofsteelcastattemperaturesbetween1000℃and1200℃inN2-O2andN7-H2Oatmospheres.ForoxidationofCucontainingsteel,CuenrichedphasewasformedbythepreferentialoxidationofFeandtheenrichmentandmigrationbehaviorofCudependsontheoxidationtemperature,steelchemistryandatmospherecondition.NiinsteelinducedtheformationofsolidCuandNienrichedphaseatsteel/scaleinterfaceandinscalelayerandtheformationofunevensteel/scaleinterface,whichsuppressestheCuenrichmentbecauseofextrusionofCuenrichedregionbeforetheformationofliquidphase.Ontheotherhand,SnadditionpromotestheliquidCuformationatsteel/scaleinterfaceandpenetrationintograinboundaryofCuenrichedphasebydecreasingsolidustemperatureandsolubilitylimit.Inaddition,foroxidationat1200℃,thebehaviorofCuatandaroundthesteel-scaleinterfacewasfounddependenttoalargeextentonmorphologyoftheoxidescaleformedduringoxidation.Attheearlystageofoxidation,Cu-richphaseformedandaccumulatedatthesteelscaleinterfaceunderbothO2-N2andH2O-N2atmospheres.Astheoxidationproceeded,however,Cuenrichmentatanditsmigrationfromthesteel-scaleinterfacewerevastlydifferentfordifferentoxidizingatmospheres.InthecaseofO2-N2oxidation,anoxidelayerformedinitiallyatthesteelsurface,butsoonafteragapwasdevelopedatthesteel-scaleinterfaceandgrewinitssize,whichpracticallyseparatedthescalefromthesteelsubstrate.Thescalelayerformedunderthisconditionwasporous.TheCu-richphaseinitiallyformedattheinterfacewasfoundmigratingtothescalelayer,leavingnoCu-richphaseattheinterface.InthecaseofH2O-N2oxidation,however,thescalelayerformedwasdenseandtightlyattachedtothesteelsurface,andtheCurich-phasecontinuedto

简介：ItisfundamentallyimportanttounderstandtheinfluenceofstrainonthedensityofdeformationtwinsinTWIPsteelbecausetwinningisitsdominantdeformationmechanism.ThedeformationbehaviorofaFe-30Mn-4Si-3Al-0.097CsteelhasbeeninvestigatedbyX-raydiffraction(XRD),electronbackscatterdiffraction(EBSD)andtransmissionelectronmicroscopy(TEM)techniques.Samplewithanaveragegrainsizeof10μmwasdeformedincold-rollingwithareductionof10%,20%,30%,40%,50%,60%and70%,respectively.Themechanicalpropertiesofthecold-rolledsampleswerefurtherinvestigatedbytensiletests.Theyieldstrength(σy)andultimate-tensile-strength(σUTS)oftheas-preparedsampleis480MPaand850MPa,respectively.However,undercoldrollingdeformation,thetensilestrengthobviouslyincreaseswithanincreaseinrollingreduction.Thesamplewitharollingreductionof10%exhibitsσyof610MPaandσUTSof-1000MPa.Theyieldstrengthandtensilestrengtharefurtherenhancedupto1320MPaand1378MPaforthespecimenwitharollingreductionof70%,regardlessofthepoorductilityof6.7%.ThedeformationmicrostructureswerestudiedbyEBSDandTEMobservations.Itisfoundthat,withincreasingrollingreduction,theaveragedistancebetweendeformationtwinsdecreasesgraduallywhilethedensityofdeformationtwins(thelengthoftwinboundaryinunitarea)exhibitamaximumvalueat40%cold-rolling+tension.Carefullystatisticsanalysisrevealsgrainorientationiscloselyrelatedtothedeformationtwinsandtheunderlyingmechanismgoverningthetwinningisdiscussed.

简介：Theeffectsofthesubstratetemperatureonthedepositionandmicrostructureofthe304stainlesssteel(SS)coldgasdynamicspraying(CGDS)coatingswereinvestigated.Itwasfoundthatthehighersubstratetemperaturecouldincreasethedepositionrateofthe304SSparticles,eventheoxidefilmsexistedattheinterface.Therewasacriticaloxidefilmwithathicknessof3-4μmwhichcouldbedestroyedbytheimpactedparticles.Themicro-hardnessandmicrostructureofthe304SScoatingsunderdifferentsubstratepreheatingtemperatureswerealmostthesame.

简介：Inthisstudy,threekindsofdual-phase(DP)steelswereusedtoinvestigatetheinfluenceofsiliconcontentandintereriticalannealingtemperatureontheirmicrostructures,mechanicalproperties,andwork-hardeningbehaviors.Byaddingsiliconandmatchingthecriticalannealingtemperature,anewDPsteel(1.0Siandintercriticallyannealedat790℃)thatexhibitsanexcellentcombinationofultrahighstrengthandadequateductilitywasobtained.Variationsinthestrength,elongation,andfracturemechanismofthespecimenswithrespecttodifferentintercriticalannealingtemperatureswerecorrelatedtomicrostructuralfeatures.Withanincreaseinthesiliconcontent,thereisnosignificantchangeinthemartensiticbandstructureorferritemorphology.Atthesameannealingtemperature,theyieldstrengthandyieldstrengthratioofthespecimensdecreased,butatdifferentannealingtemperatures,thetensilestrengthwasreduced.TheHollomonanalysisresultsindicatethattheworkhardeningbehaviorobeysatwo-stagework-hardeningmechanism.Withanincreasingintercriticalannealingtemperature,the"transitionstrain"shiftstotheleft,andwithanincreasingsiliconcontent,the"transitionstrain"shiftstotheright.Thesurfaceexhibitsductilefracturescharacterizedbyahighdensityofmicrovoiddimples.Withanincreaseinthesiliconcontent,theaveragedimplesizeonthefracturesurfacedecreasesandtheplasticityofthematerialincreases.