简介：Theadvancedultra-supercriticalpowerplantsofthefuturewillutilizesteampressuresandtemperaturesthataretoohighfortraditionalferriticsteels,thusrequiringausteniticmaterials.Oldernickel-basesuperalloyssuchas263and617wereinitiallyevaluatedundertheEuropeanTHERMIEprojectbeginninginthe1990s.Anentirelynewage-hardenedalloy740whichpossessesexceptionalfiresidecorrosionresistanceandcreepstrengthwasalsodevelopedforboilertubingcapableofservingat700C.Subsequently,interestintheUSAconsideredotherproductformssuchassteamheaderpipingandsteamturbineforgingsforserviceashighas760C.Amorestableandweldablealloyversionnowcalled740Hwasdevelopedtomeetthesemoredemandingconditions.Thispapersummarizesthecurrentstatusofworkonalloys740and740H.

简介：Thispaperdescribesthealloydesignphilosophyfortheimprovementoflong-termcreepstrengthoftemperedmartensitic9Crsteel,includingweldedjoints.Thecreeplifetrisinverselyproportionaltotheminimumcreeprateεmintimestheincreaseincreepratebystraindlnε/dεintheaccelerationregionastr=1.5/[(εmin)（dlnε/dε）].Theparametersεminanddlnε/dεarecloselycorrelatedwiththetimetominimumcreepratetmandthestraintominimumcreeprateεm,whichcharacterizethecreepdeformationbehaviorinthetransientregion.Theboundaryandsub-boundaryhardeningisshowntobethemostimportantstrengtheningmechanismincreepof9Crsteelandisenhancedbyfinedispersionsofprecipitatesalongboundaries.TheadditionofboronreducesthecoarseningrateofM23C6carbidesalongboundariesnearprioraustenitegrainboundariesduringcreep.Theenhancementofboundaryandsub-boundaryhardeningincreasesthetmanddecreasestheεmin,whichimprovesthecreeplife.Theboundaryandsub-boundaryhardeningissignificantlyreducedinfine-grainedregionofheataffected-zone（HAZ）ofconventionalsteelP92weldedjoints,promotingTypeⅣfracture.InNIMS9Crboronsteelweldedjoints,thedistributionofcarbonitridesalongboundariesaresubstantiallythesamebetweentheHAZandbasemetal,suppressingtheTypeⅣfracture.

简介：Chinaisanimportantcountryinironandsteelindustry.Powerelectronicsconvertersarewidelyused.Forthecoldrollingmillsofhighspeed,AC-DC-ACconvertersshouldbeused.Inthepaper,thedesignandthecontrolsystemofthelargepowerthree-levelAC-DC-ACconverterwithIGCTsisinvestigated,andaback-to-backlargepowerthree-levelAC-DC-ACconverterwithIGCTshasbeengot.Withaseriesexperiments,theperformanceoftheconverterisexamined.Theexperimentresultindicatestheconverterreachesthedesignrequirementanditshowsexcellentperformance.Theconvertersystemhasbeenputintousesafely.ItisestimatedthattheAC-DC-ACconvertersystemwillbeusedinthedrivesystemsforrollingmillsinthenearfuture.

简介：Thispaperbrieflysummarizedthedevelopmenthistory,productcatalogueandmagneticpropertiesofnonorientedelectricalsteelsheetsatBaosteel,aswellasthedevelopmentandapplicationofhigh-value-addedsteelgrades.Recentadvancesinmanufacturingelectricalsteelsheetswerealsointroduced,includingtechnologiesforcontrollinginclusion,forproducinghigh-gradesteelstripsbyatandemrollingmillandforcontrollingthetransversethicknessdifferenceofsteelsheets,andthedevelopmentofenvironmentallyfriendlycoatings.

简介：Inthelastthreedecadesnewstrongermodified9%Crsteelshavebeenintroducedinnewpowerplantswithsteamparametersupto300bar(1bar=10~5Pa)and600℃.Inordertofurtherincreasethesteamparametersofsteelbasedpowerplantsuptoatargetvalueof650℃/325baritisnecessarytodoublethecreepstrengthcomparedwithtodaysstrongest9%Crsteels,andatthesametimetheresistanceagainststeamoxidationmustbeimprovedbyadding12%Crtothesteel.However,sofarallattemptstomakestronger12%Crsteelshavebeenunsuccessfulbecausethehighchromiumcontentintroducedseveremicrostructureinstabilitiesinthetestedsteels.Recently,itwasfoundthatthemicrostructureinstabilitiesin11%-12%CrsteelscanbeexplainedbytheprecipitationofcoarseCr(V,Nb)NZ-phases,whichdissolvefine(V,Nb)Nnitrides.AnewpossibilitytousetheZ-phaseforstrengtheningof12%Crsteelshasbeenidentified,andthedevelopmentofstablestrongmartensitic12%Crsteelsbasedonthisconceptisexpectedtoallowtheconstructionof325bar/650℃steampowerplantsallbasedonsteel.

简介：Basedonthemanufactureofefficientnon-orientedsiliconsteelgrade,theeffectsoftinandsulphuronmagnetismanditsinteractionwasdiscussed.Theresultsshowedthatforpresentwork,minortincouldimprovemagneticinductionsharplyandhadlittleeffectoncorelosswhenthesulphurcontentbelow10×10-4%.TheprecipitationofAlNcouldbeprohibittedbytin,remarkably.Asthenucleus,tincouldremovalanyinclusionswhichsizewas0.5μmorabove,andhadlittleeffectoninclusionswhichsizewasbelow0.5μmasakeyfactorforcoreloss.Forfinalsample,themagneticinductionwasimprovedthroughthechangeofsteeltexturebytin.Therelationshipbetweenmagneticinductionandtin,sulphurcontentcouldberegressed:B=1.69-4.37S+0.30Sn.Fromtheregressionformulation,magneticinductioncouldbeimprovedfor0.03Twhen0.01%tinwasaddedundertheconditionofrelativelylowsulphurcontent.

简介：Bymeansofthenumericalsimulationmethod,themathematicalmodelofinclusionsmovementinthemoldisestablishedundertheconditionofausteniticandferriticstainlesssteelslabproduction.Accordingtothesimulationresults,themainzonesforinclusionparticlesaccumulationwerefoundandmanyfactorsthataffectedfloating-upprobabilityofinclusionparticleswereidentified.Thesefactorsincludetheinclusionparticlesize,thecastingspeedandtheslabwidth,etc.Itisbelievedthattheinclusionparticlesizeisthekeyoneamongthesefactors.