轴承钢GCr15大方坯连铸工艺研究

GCr15____________________________________________________GCr15___________________________________________________________________________20070308G20044092TF777.1_________________________20070308GCr15GCr15StudyontheContinuousCastingProcessofGCr15Blooms100083CandidateZhangJiansheSupervisorZhangJiaquanSchoolofMetallurgicalandEcologicalEngineeringUniversityofScienceandTechnologyBeijing30XueyuanRoadHaidianDistrictBeijing100083P.R.CHINA-1-_________________________________________________________-2-20034GCr15GCr1510.3m/min0.7m/min35.62mm11.33mm2200.1m/min3.3m3101mm41050.1m5150m3/h170m3/h0.15L/kg0.2-0.3L/kg-3-StudyontheContinuousCastingProcessofGCr15BloomsAbstractShigangSteelhasbeguntoproducebearingsteelsinceAprilofyear2003withtheprocessofLDLFrefiningbloomcastingsectionrolling.Inthispaper,theheattransferandcoolingpracticehavebeenstudiedfortheimprovementoftheinternalqualityofthebloomcastings.Basedontheanalysisoftheheattransferbehaviorofthecontinuouslycastbloom,therelatedcoolingandsolidificationmodelhasbeendevelopedwiththeconsiderationofthepropertiesofbearingsteelandthemechanicalstructureofthecaster.Withtheapplicationliquidsteelrefinementandreasonableelectricalmagneticstirringinthemould,theinfluenceofcastingspeedandsuperheatetc.onthesolidificationprocesshasbeencalculatedandanalyzedforbloomcastingofGCr15bearingsteel.Themouldcoolingandsecondarycoolingparametershavebeenanalyzedandoptimizedbasedonthecoolingcalculationandin-situexperiments.Thefollowingconclusionshavebeenbroughtout:(1)Castingspeedhasaremarkableinfluenceontheshellthicknessattheexitofthemould.Withgivencoolingintensity,theshellthicknesscoulddecreasefrom35.62mmto11.33mmwhilethecastingspeedincreasingfrom0.3m/minto0.7m/min.(2)Littleinfluenceofcastingspeedonthesurfacetemperaturehasbeenprovenduringbloomcasting.Withgivencoolingwaterflowrate,thebloomsurfacetemperaturefluctuatesunder20withnormalconditionofspeedchange.However,thecastingspeedhasstronginfluenceonthemetallurgicallengthoftheblooms.Thelengthcouldchange3.3mwithevery0.1m/minvariationofthecastingspeed.(3)Thechangeoftheshellthicknessatthemouldexitdoesnotexceed1mmwiththevariationofsuperheatunder10.(4)Theinfluenceofsuperheatonthebloomsurfacetemperaturedoesnotexceed10normally.Withevery5fluctuationofthesuperheat,themetallurgicallengthhasachangeabout10.mm.(5)Withtheoptimizedcoolingpractices,theporosityandcentrelinesegregationcouldbeimprovedeffectivelywhile,forexample,thecooingflowrateofmouldincreasingfrom150m3/hto170m3/h,andsecondarycoolingwaterflowrateincreasingfrom0.15L/kgto0.2-0.3m3/h.-4-Itisshowninthepaper,withtheadoptionofoptimizedfirstandsecondarycoolingpractices,theinternalqualityofthecastbloomcanbeimprovedtomeettherequirementofthefollowingrollingoperationforthepresentcaster.KeyWordsbearingsteelcontinuouscastingsolidificationmodel,coolingparameters-1-..................................................................................................................................1Abstract.....................................................................................................................................3..................................................................................................................................11..............................................................................................................................21.1..................................................................................21.1.1............................................................................21.1.2...............................................................31.1.3...................................................................71.1.4...................................................................................................151.1.5.................................................161.2....................................................................................171.3.............................................................................................201.3.1.......................................................................................................201.3.2.......................................................................................................212GCr15..............................................................................................222.1.................................................................................................222.1.1..........................................................................................222.1.2......................................................................................252.2GCr15...................................................................................272.33#.................................................................................282.4.............................................................................................292.5.................................................................................................3033#...........