简介:Theeffectsofthefinalelectromagneticstirring(EMS)onthesolidificationstructureof60Si2CrVAThighstrengthspring(HSS)steelofcontinuouscasting(CC)billetshasbeenstudied.Theanalysisofthesolidificationstructureisbasedonthecomparisonbetweenthemacrostructure,microstructure,carbonsegregationanddefectsofthe60Si2CrVATbilletwithmold-electromagneticstirring(M-EMS)andthosewiththeM+finalsolidificationzoneelectromagneticstirring(F-EMS).ItisfoundthatthesolidificationstructureofthebilletwiththeF-EMSisimprovedwiththetightnessofthebilletandtheincreaseintheratiooftheequiaxedstructure,theinnerporosityandtheshrinkageareremarkablyreduced,andthattheratioofcentralcarbonsegregationsharplydecreases.Meanwhile,thesecondarydendritearmspacing(SDAS)isimproved,andtheratioofcentralequiaxedgrainconsiderablyincreases,whichresultsinfinergrains.Therefore,thequalityofthebilletisenhancedwiththeF-EMS.
简介:ToimprovethemechanicalpropertiesofWC-Al2O3composites,theeffectsoftraceamountofCeO2additivesonthemicrostructureandmechanicalpropertiesoftheWC-Al2O3compositespreparedbyhotpressingwereinvestigated.TheresultsrevealedthattheWC-Al2O3compositesdopedwith0.1%CeO2possessedrefinedmicrostructureandenhancedmechanicalpropertiescomparedwiththatoftheundopedWC-Al2O3composites.TraceCeO2suppressedthedecarburizationofWC,promotedthemicrostructuralrefinement,andimprovedtheinterfacecoherenceoftheWCmatrixandAl2O3.When0.1%CeO2wasaddedtotheWC-Al2O3composites,theeffectofCeO2resultedintheachievementofarelativedensityof98.82%withanexcellentVickershardnessof16.89GPa,combiningafracturetoughnessof9.85MPa·m1/2withanacceptableflexuralstrengthof1024.05MPa.
简介:Steelmakingisenergyandmaterialintensive.Thatiswhysteelisalwaysdemonizedandconfrontedwithincriminationsandrequirementsforreductionofitsenvironmentalimpact.Thosepuredemands-likeforemissiontradingareshort-sightedastheydonotbaseonanintegratedapproach.InsteadtheymerelyconsiderCO2emissionsduringtheproductionprocess.Aforward-looking,globalclimateandenvironmentalpolicyneedsasustainablelifecycleapproach.Thereforeitmustforexamplealsotakeintoaccountthecontributionofsteeltowardscuttingemissionsinitsapplication-intheenergy.automotiveandhouseholdsectors.Steelwillplayakeyroleinclimateprotection.One-thirdoftheremainingCO2reductiontargetplannedinGermanyby2020canonlybeachievedwiththehelpofinnovativesteelproductsandtheirapplications.ThisistheconclusionofanindependentstudybyTheBostonConsultingGroup(BCG)onbehalfofSteelInstituteVDEh,andGermanSteelFederation.ThestudycomparesCO2savingsfromimportantinnovativesteelapplications(suchasmoreefficientpowerstations,windturbines,orlightervehicles)withCO2emissionscausedbysteelproduction.Byadoptingthiscomprehensiveperspective,thestudyforthefirsttimeprovidesaCO2balanceforthematerialsteelbycomparingtheCO2reductionsmadepossiblethroughinnovativesteelapplicationswiththeCO2emissionsresultingfromsteelproduction.ThebalancewascalculatedonthebasisofeightselectedinnovativesteelapplicationsinGermanyfortheperiod2007to2020,wherebytheCO2emissionscausedbysteelproductionwereconsideredthroughouttheentirelifecycleoftheparticularsteeluse.Fortheselectedexamples,theuseofinnovativesteelsresultedinatotalsavingspotentialof74MtofCO2in2020.Thecalculationsarebasedonconservativeassumptions;forexamplewithoutcountingofpotentialsbyexportedsteelorbycomparisonwithcompetitivematerials.TheproductionofsteelinGermany,includingtheextractiono