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ID:11237603
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页数:5页
时间:2018-07-10
《金属凝固原理习题 2》由会员上传分享,免费在线阅读,更多相关内容在行业资料-天天文库。
1、Chap.1HEATFLOWINSOLIDFICATION1-3Alargeslabofaluminum,25cmthick,ispouredinasandmoldwithnosuperheat.(a)Howlongwillittakefortheslabtosolidify?(Assumenegligibleresistancetoheatflowatthemold-metalinterfaceandwithinthesoliditymetal)(b)Showschematicallycoolingcurvesforathermocouple6.25cmformthesurfac
2、eandoneatthecenterofthecasting.(Remember,thesolidifiedportionofthecastingremainsveryclosetountilthecastingiscompletelysolid)1-10(a)Aslabofiron,25cmthick,ispouredwithnosuperheatintoanironmold.Calculatethesolidificationtimeassumingnomold-metalinterface.(b)Howmuchlongerisrequiredforsolidification
3、oftheslabinasandmold?Neglectresistancetoflowwithinthesolidifiedmetalandatthemold-metalinterface.(c)Whatpercentageerrordidyouintroducein(b)byneglectingresistancetoheatflowwithinthesolidifiedmetal?1-14Youaretohelpdesignaverticalcontinuous-castingmachinetomake8-in-thicklow-carbonsteelslabs.Castin
4、gspeedtobeaimedforis100in/min.Whatistheminimum-heightcastingtoweryoumustplantobuild?Chap.2PLANEFRONTSOLIDIFICATIONOFSINGLE-PHASEALLOYS2-1AGe-Gaingotcontaining10ppmGaissolidifiedatR=8*cm/swithnegligibleconvection.Showschematically,thecompositionalongthelengthofthefullysolidifiedingot,givingthei
5、nitialcompositionandlengthsoftheinitialandfinaltransient.Assume=5*/s,k=0.1.2-5AnAl-1%Cualloyisnormallysolidifiedwith=k.ThephasediagramforthisalloyisschematicallyasinFig.2-3with=33%Cu,=5.65%Cu,=660℃,and=548℃.(a)Howmucheutecticwillbepresentinthefinallysolidifiedbarassumingnosoliddiffusion?(a)Ata
6、solidificationvelocityofcm/s,doyouexpectsignificantdiffusioninthesolid?[Note:=0.29*/s;R=1.99cal/(mol)(°K).]Chap.3CELLULARSOLIDIFICATION3-2AnAl-1%Cualloyisgrownbynormalfreezingat3*cm/swithconvectioncompletelysuppressed.(ThephasediagramforthisalloyisasshownschematicallyinFig.2-3,=33%Cu,=5.65%Cu,
7、=660℃,=548℃,andconstantkand;=3*/s.)3-3WhatthermalgradientwouldberequiredtomaintaintheplanefrontinProb.3-2,accordingtotheMullinsandSekerkainterfacestabilitycriterion?(Assumethethermalconductivityofthesolidishalfthatoftheliquid;σ=1.2*cal/
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