简介:Thestudyintroducesthechemicalcomposition,mechanicalproperties,physicalpropertiesandproductionprocessesoftheFe-23Mn-2Al-Vausteniticsteel.Investigationsweremadeintotheformationofcracksinthehot-rolledFe-23Mn-2Al-Vsteelplates,withopticalmicroscopy(OM),scanningelectronmicroscopy(SEM)andenergydispersivespectrum(EDS).Theresultshaveshownthatintergranularoxidationinthereheatingfurnaceisthemaincauseofthecracksonthesurfaceofthehot-rolledsteelplates.Thesurfacecrackingcanbelargelyavoidedbycontrollingtheremainingoxygencontentinthereheatingfurnaceandimprovingcontinuouscasting(CC)processestoincreasethethicknessoffineequiaxedgrainlayerofthesteelslabs.
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:Coarsening,embrittlementandcorrosionsensitizationinahightemperatureheat-affectedzone(HTHAZ)arethemajorproblemswhen12%chromiumlowcarbonstainlesssteelisbeingwelded,whichinducethedeteriorationoftheimpacttoughnessatalowtemperatureandintergranularcorrosionresistanceproperty.ThisstudyinvestigatesthecorrespondingmicrostructuresinHTHAZwithdifferentchemicalcompositionsandheatinputsthroughthermalsimulationtests.Theresultsshowthatthemartensitecontentincreaseswiththedescendingofferritefactor(FF)whenFFisbelow9.0andheatinputinfluencesthemicrostructureofhighFFsteelinHTHAZ.Martensiteof12%CrstainlesssteelinHTHAZwithonlyNbstabilizationreticularlydistributesatferritegrainboundaries.