简介:CausesforcentralshrinkpipeofGCr15bloomswereanalyzed.Countermeasurestotacklewithsuchdefectwerepracticed,includingsuitablesecondarycooling,softreductionandcastingspeed,aswellasstrictsuperheatcontrol.Theresultsshowthatthequalityofbloomcastingsissignificantlyimproved.
简介:Martensiticstainlesssteelcontaining12%-18%Crhavehighhardnessduetohighcarboncontent.Thesesteelsarecommonutilizedinquenchingandtemperingprocessesforknifeandcutlerysteel.Thepropertiesobtainedinthesematerialsaresignificantlyinfluencedbymatrixcompositionafterheattreatment,especiallyasCrandCcontent.Comprehensiveconsideredthehardnessandcorrosionresistance,anewtypemartensiticstainlesssteel6Cr15MoVhasbeendeveloped.Thisstudyemphaticresearchestheeffectofheattreatmentprocessesonmicrostructureandmechanicalpropertiesof6Cr15MoVmartensiticstainlesssteel.Thermo-Calcsoftwarehasbeencarriedouttothermodynamiccalculation;opticalmicroscope(OM),scanningelectronicmicroscope(SEM)andtransmissionelectronmicroscope(TEM)havebeencarriedouttomicrostructureobservation;hardnessandimpacttoughnesstesthavebeencarriedouttoevaluatethemechanicalproperties.Resultsshowthattheequilibriumcarbidein6Cr15MoVsteelisM23,C6carbide,andfinelydistributedofM23C6carbidescanbeobservedonannealedmicrostructureof6Cr15MoVstainlesssteel.6Cr15MoVmartensiticstainlesssteelhasawiderquenchingtemperaturerange,thehardnessvalueofsteel6Cr15MoVcanreachto60.8-61.6HRCwhenquenchedat1060-1100℃.Finelydistributedcarbideswillexistinquenchedmicrostructure,andeffectivelyinhabitthegrowthofaustenitegrain.Withtheincreasingofquenchingtemperature,thevolumefractionofundissolvedcarbideswilldecrease.Theexcellentcomprehensivemechanicalpropertiescanbeobtainedbyquenchedat1060-1100℃withtemperedat100-150℃,anditismainlyduetothehighcarbonmartensiteandfinegrainsize.Atthesetemperatureranges,thehardnesswillretainabout59.2-61.6HRCandtheCharpyU-notchimpacttoughnesswillretainabout17.3-20J.Themorphologyofimpactfracturesurfaceoftestedsteelissmalldimpleswithasmallamountofcleavageplanes.Theareaofcleavageplanesincreaseswiththeincreas