13春学期《连铸坯凝固与质量控制》在线作业2

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1、NortheasternUniversity,14spring,13autumn,13springsemester,"continuouscasting"NortheasternUniversity,14spring13autumnEast13springsemester〃continuouscastingsolidificationandqualitycontrol"onlineoperation2Totalscore:100testtime:-RadioexaminationAmultiple-choicequestionRadioexaminationquestions(10q

2、uestions,70points)OneWhencomparedwithhighcarbonsteelandlowcarbonsteel,whichkindofsteelhasalargerairgapduringthesolidificationofthemould?A.lowcarbonsteel,bigger;B.highcarbonsteelisbigger;Fullmarks:7TwoInthesolidificationprocessofeutecticalloy,whichphasefirstprecipitates,mainlydependsonthealloyCo

3、mposition,followedbythemodificationofthealloy,istheanalysiscorrect?A.analysisisincorrect;B.analysisiscorrect;C.D.Fullmarks:7ThreeThetypicalsolidificationstructureofthecontinuouscastingslabissimilartothetypicalsolidificationstructureoftheingot,butthereisnotmuchdifferencebetweenthem・Isthediscussi

4、oncorrect?A.'sstatementisincorrect;B.Discusscorrectly;C.D.Fullmarks:7FourThemouldelectromagneticstirringhasthefunctionofsimulatinglowtemperaturecasting・Whatisthefollowingdiscussion?TheelectromagneticstirringoftheA.mouldacceleratesthecoolingoftheliquidsurface;TheelectromagneticstirringoftheB.mol

5、dacceleratesthecastingspeed;C.Electromagneticstirringofmouldpromotesheattransferinmould;D.Fullmarks:7FiveHowisthethermalstressproducedduringthesolidificationofcontinuouscastingbillet,whichofthefollowingiswrong?ThereiscompressivestressonthesurfaceofA.billet;TheB.solidificationfronlhastensilestre

6、ssduetotheunevenvelocity;CompressivestressatsolidificationofC・center;D.Fullmarks:7SixIntheprocessofnon-equilibriumsolidificationofpuremetals,nucleationandgrowthprocessismainlycausedbythermalundercooling・Istheanalysiscorrect?A.analysisiscorrect;B.Incorrectanalysis;C.D.Fullmarks:7SevenSometimes,t

7、heuseofterminalelectromagneticstirringisnotidealfortheimprovementofthecenterquality・Isitnecessarytocombinethesoftpressingwiththeendelectromagneticstirring?A.isnecessary;A.isnotnecessary;C.D.Fullmarks:7EightIsittruethatthesurfacean