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：TheFe-Ti-Nmateralloywaspreparedthroughthein-situreactionofnitrogengaswiththeFe-Timelt.ScanningelectronmicroscoperesultsshowthattheparticlesuniformlydistributedintheironmatrixwereTiN.ThedeliberatelypreparedFe-Ti-Nmasteralloywasemployedforthe409Lferriticstainlesssteelinanattempttorefinetheas-castsolidificationstructure.ItwasfoundthattheeffectivenessofFe-Ti-Nmasteralloyonrefiningoftheas-cast409Lferriticstainlesssteelwasaffectedbyadditionlevel,holdingtimeandmeltstemperature.Itwasfoundthattheaverageequiaxedgrainsizedecreasedfrom1503μmto303μm,theproportionofequiaxedgrainzoneincreasedfrom14%to100%withincreasingtheFe-Ti-Nmasteralloyadditionlevelto2.5%.Theproportionofequiaxedgraindecreasedfrom85%to4%asthesolidificationtemperatureincreasedfrom1803Kto1883K.Whentheholdingtimereachedto8min,thesolidificationstructuresof409Lferriticstainlesssteelshowextremepointsintheproportionofequiaxedgrain.Itisclearthatthegrainrefiningefficiencygraduallyfadeawaywiththeincreasingoftheholdingtimeattheverybeginning.However,whentheholdingtimecontinuestoincreaseandexceedstheextremepoint,thegrainrefiningefficiencyoftheFe-Ti-Nmasteralloyrecoveredtoacertaindegree.Theexperimentalresultsmentionedabovehavebeenanalyzedintermsofthermodynamics.Underappropriateconditions,theFe-Ti-Nmasteralloyusedforgrainrefinementofthesolidificationstructureof409Lferriticstainlesssteelmayhavegoodprospectsforindustrialapplications.

简介：Supercriticalwaterreactor(SCWR)wasproposedasaGenerationⅣconceptforbuildinglargecapacitynuclearpowerplants.ComparingwiththepresentGenerationⅡandⅢlightwaterreactors,SCWRpossessesgreatadvantagesof10%higherefficiency,simplersystemdesign,bettersustainability,andsoon.However,theselectionofmaterialsforfuelcladdingandreactorinternalsofSCWRisfacingagreatchallenge.Corrosioninsupercriticalsteamisofthefirstimportantissuetobesolvedtomeetthestringentrequirementofthereactorinternalcomponents.Corrosionscreeningtestswereconductedoncandidatematerialsfornuclearfuelcladdingandreactorinternalsofsupercriticalwaterreactor(SCWR)instaticandre-circulatingautoclaveatthetemperaturesof550,600and650℃,pressureofabout25MPa,deaeratedorsaturateddissolvedhydrogen(STP).NickelbasealloytypeHastelloyC276,austeniticstainlesssteelstype304NG,AL-6XN,HR3C.NF709andSAVE25,ferritic/martensitic(F/M)steeltypeP92,P122and410,andoxidedispersionstrengthenedsteelMA956,aretested.Thispaperpresentscorrosionrate,andfocusesontheformationandbreakdownofcorrosionoxidefilm,andproposesthefuturetrendforthedevelopmentofSCWRinternalstructurematerials.

简介：Oneofthepathwaysforachievingthegoalofincreasingtheefficiencyofcoal-firedpowerplantsandreducingtheemissionofpollutantsandCO2isbyimprovingthesteamtemperatureandpressure.Buttheincreaseofsteamparametersdependonthedevelopmentofnewhigh-temperaturemetalmaterials.ThispaperpresentedtheconstructivesuggestionsoncriticalmaterialsselectionforChina’snewgenerationof700℃cleanandhigh-efficiencycoal-firedboilerbysummarizingtheresearchanddevelopmentsituationofcriticalmaterialsforcoal-firedboilersoperatingat700℃/35MPaoftheEurope,JapanandUSA.

简介：Incontinuousannealinglines/hotgalvanizing,stripsareguidedbyupperandlowerrollsinanalternateupanddownverticalmotion.Thiskindofprocessconsistingofheating,soaking,andcoolingfurnaces（orzones）hasseveraladvantagesintermsofproductivityandproductquality.Mainproblemsencounteredincontinuousannealinglinesaremisguidingandformationofbuckling.Thestripbucklingcausesthestriptoberejectedand,intheworstcase,thestripbreaksandthecontinuousannealinglinesarecompelledtostop.Inthispapertheelastic-plasticmodelofthestriptravelingandthecorrespondingboundaryconditionwereconstructeddependantonthetheoryofmechanic.Simulationsareperformedintwosteps.First,ahomogeneouslongitudinaltensilestressisappliedatoneendofthestrip,theotherendofthestripandtherollarerestricted.Inthesecondstep,theappliedtensionremainsconstant.Auniformdisplacementisappliedtotheotherendofthestripandarotationtotheroll.Thetransversecompressivestress,thebucklingformationduringstriptravelingprocess,thelocationforthebucklingtakingplaceandthebucklingcriterionwereinvestigatedsystematically.Theresultshowsthatthetransversecompressivestressincreaseswiththeincreaseofthetensilestressandthecrownofthetaperedroll.Becausethecontactareabetweenthetaperedrollandthestripincreasewiththedecreaseofthecrown,thetensilestressdistributionismorehomogeneousinthetransversedirectionofthestrip.Anadditionaltransversecompressivestressiscreatedandabucklingisalsoobservedduetothefrictionduringthestripmotioninthesecondstep.Oncethebucklingisappearance,itisveryhardtoberemovedonlythroughdecreasingtheappliedlongitudinaltension,becausethestripwrinklestillkeepshighlevelduetotheeffectofthebuckledstrip,thewrinklewouldevolveintobucklingeventually.Thebucklingformationprocesspredictedbythefiniteelementmodelisverysimilartothose