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:Inthispaper,aspiralmagneticfieldelectromagneticstirrer,whichcanseparatelyinducetwodifferentmagneticfields,isintroduced.Thecorrespondingcentralmagneticfluxcurvesofthestirrerweremeasuredbytwodif
简介:CuprecipitationbehaviorsintwoCu-bearingausteniticantibacterialstainlesssteels,type304andtype317L,weresystematicallystudiedbyusingrelativelysimplemethodsformaterialsanalysis,includingmicro-hardness,electricalresistivity,electrochemicalimpedancespectroscopy,X-raydiffractionanddifferentialscanningcalorimetry.Theresultsindicatedthatafteragingatelevatedtemperature,themicro-hardness,electricalresistivity,electrochemicalimpedanceandlatticeconstantofthesteelwereallvariedatdifferentdegreesduetotheprecipitationandgrowthofCu-richphases.TheresultsalsoshowedthattheheatevolutionduringtheprocessofCuprecipitationcouldbesensitivelydetectedbymeansofdifferentialscanningcalorimetry,obtainningthestartingtemperature,peaktemperature,peakareaoftheCu-richprecipitation,andeventheactivationenergybycalculation.TheresultsconfirmedthattheCu-richphasedprecipitationintheCu-bearingausteniticantibacterialstainlesssteelshouldbeathermalactivationprocesscontrolledbyCudiffusion.AllthematerialsanalysismethodsusedinthisstudycanbemoresimpleandeffectiveforapplicationinR&DoftheCu-bearingantibacterialstainlesssteels.
简介:Thereisanincreasingtrendforproducingcopper-containingsteels,withcopperbeingeitheraresidualelementfromscrapsoranintentionaladdition,i.e.,inweatheringsteel.Theissueofsurfacehotshortnessoccursduringthehotworkingofsteelscontainingcopper,andasignificantamountofworkhasbeenperformedonthistopic.Thispaperprovidesareviewofrelatedstudiesonthisphenomenon.Theformationmechanism,asanalyzed,istheliquidmetalembrittlementcausedbytheliquidcopperpenetrationintoaustenitegrainboundariesatthemetalsurface,wherethecopperoriginatesfromtheselectiveoxidationofthesteelathightemperature.Onthebasisofthemechanism,moreimportanceisplacedonanalyzingtheeffectonthephenomenonbyvaryingthecontrollingfactors,includingtheheatingprocess,alloyingadditions,anddeformationconditions.Possiblesolutionstotheproblemarefinalized,andsomefurtherworkmustbeperformedinthefuture.
简介:SomenewNi-saving25Crduplexstainlesssteels(DSS)havebeendeveloped.Theresultsindicatethatthealloyhasabalancedferrite-austeniterelationafterhotforgeandsolidsolutiontreatmentat1000℃.TheelementsWandCuhaveamarkedeffectonthemicrostructureofthealloy.ThepittingpotentialofthesteeladdingWandCuelementsreachesthemaximumvalueof435mV.Thetensilestrengthandpercentageofareareductionofallsteelsinthispaperare800-900MPaand60%-70%,respectively.Thetensileelongationsofthealloysareallabove30%.Theexperimentalsteelshavegoodcorrosionandmechanicalproperty.
简介:Withpricesformetalresourcessuchasnickelandmolybdenumsoaring,thereisaheightenedsenseofcrisisconcerningresourcescarcity.WhileType304,themostcommonstainlesssteel,offersexcellentcorrosionresistance,itspriceisaffectedsignificantlybythecostofnickelbecauseofits8%nickelcontent.ThestainlesssteelthathasthesamecorrosionresistanceasthatofType304anddoesnotcontainnickelandmolybdenumhasbeenrequired.JFESteelCorporationhasdevelopedanew21%Cr-0.4%Custainlesssteel,theworld’sfirstferriticstainlesssteel,whichoffersequivalentcorrosionresistancetoType304whilecontainingabsolutelynonickelormolybdenum,tworaremetals.Thenewlydevelopedsteelcontains21%chromiumwiththeadditionof0.4%copper.Thedevelopmentofthesteelisbasedonanewdiscoverythatthepassivefilmsofstainlesssteelscouldbestrengthenedbythesynergyeffectofhighchromiumcontentandcopperaddition.Copperadditionenrichesthechromiumcontentinpassivefilmsafterfieldexposure.Newlydeveloped21%Cr-0.4%CustainlesssteelisadoptedformanyapplicationsasasubstitutionforType304,includingcommercialkitchenware,buildingmaterialsandindustrialmachinery.ThesteelisexpectedtobeanewstandardofaferriticstainlesssteelasasubstitutionforType304.