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电化学有关论文范文素材,与硕士生学位文开题相关毕业论文格式范文
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磁场,通过分析比较发现,在多流低频电磁铸造6063铝合金过程中,各铸流磁场之间的影响非常小.关 键 词:低频电磁铸造,换热系数,温度场,液相穴深度,电磁场
ABSTRACT
Low-frequencyelectromagiccastingisaburgeoningmouldingprocessforaluminumalloy.Thepropertiesandqualityofthealuminumalloyingotcanbeimprovedprominentlybythisprocess.Temperaturefieldofthedirectchillsemicontinuouscastingprocessisexperimentallyandtheoreticallystudiedinthispaper,andonthebasisoftheresultsoftemperaturefield,theinteractionofeachstrand'smagicfieldofmulti-strandlow-frequencyelectromagiccastingissimulatedbyANSYS.
Inordertomeasurethedynamictemperaturesoftheingot'snearsurfaceduringdirectchillsemicontinuouscasting,thermocouplesareimmersedintheliquidpoolandconsequentlyentrappedinthesolid,thealuminumalloyingotis100mmindiameter.Forwatercoolingzone,theheattransfercoefficient(HTC)iscalculatedthenbyinversemethod,andit'sthefunctionoftheingotsurfacetemperature.Firstly,theHTCincreaseswhiletheingotsurfacetemperaturedescends.Andthenwhenthetemperaturedecreasesfrom400℃to130℃,theHTCincreasessharply,andthemaxHTCisabout23000W/(m2·K)at130℃.Whenthetemperatureisunder130℃,theHTCdecreaseswiththetemperaturedescending.ThechangeoftheHTCisanalyzedtheoreticallyinthispaper.
A3-DFEMmodelofthedirectchillsemicontinuouscastingisbuiltundertherealcastingprocessesoftheexperiment.Inordertovalidateit'scorrectness,themodelisappliedtosimulatethesolidifyingprocessoftheexperimentalaluminumalloyingot.Fortheputedandmeasuredtemperatures,agoodagreementisachieved.ThenusethismodeltosimulatethesolidifyingprocessoftheФ174mmaluminumalloyingot,theemphasiswetakecareofisthesumpdepthunderdifferentcastingconditions.Whenthepouringtemperatureisintherangeof690℃to710℃,thecastingspeedisintherangeof90mm/minto100mm/min,thenthesumpdepthisintherangeof65mmto85mm.Whenthepouringtemperatureincrease10℃eachtime,thesumpdepthwillincreaseabout4~5mmcorrespondingly,andwhenthecastingspeedincrease5mm/mineachtime,thesumpdepthwillincreaseabout3~4mmcorrespondinglytoo.Thethicknessoftheshellattheendofthemoldisstudiedfinally.
ThecoilpositionofthemoldisdesignedaccordingtothesumpdepthofdirectchillcastingofФ174mmaluminumalloyandotherfactors.ThenusethenumericalsimulationsoftwareANSYStosimulatethemagicfieldofone-strandandmulti-strandlow-frequencyelectromagiccasting.Throughanalysisandparison,wefoundthatduringtheprocessofmulti-strandlow-frequencyelectromagiccastingof6063aluminumalloy,themagicfieldsofeachstrandhavelittleeffectoneachother.
Keywords:low-frequencyelectromagiccasting,HTC,temperaturefield,sumpdepthelectromagicfield
论文题目:稀土La对纯净钢组织与性能的影响
EffectofRareearthLaonMicrostructureandPropertyofThePuritySteel
研究生姓名:李峰
导师姓名:李春龙总工
协助导师:刘宗昌教授
任慧平教授
专业:材料加工工程
摘 要:
利用武钢生产的工业纯铁为原料,经过纯铝脱氧后加入纯稀土镧,利用稀土镧作为单一合金元素,冶炼稀土单一合金纯净钢.通过调整稀土加入量,冶炼出5种不同稀土含量的实验用钢.利用扫描电子显微镜,光学金相显微镜和透射电子显微镜,分析和研究了在不同稀土含量情况下,稀土对纯净钢夹杂物类型,形态的影响.通过对纯净钢组织的观察,发现稀土对钢中夹杂物有变质和球化的作用,并且形成稀土复合化合物.随着稀土含量的增加,稀土化合物有变质Al2O3,MnS夹杂作用,使之转变为LaAlO3,La2O2S,LaXSY型夹杂物.稀土夹杂物中的稀土含量与硫含量的比例也随着钢中稀土总含量的增加而变化,分别为1#:1:4,2#:3:5,3#:1:1,4#:3:2.而且稀土夹杂物弥散分布,其最大直径不超过3μm.起到细化晶粒和提高基体强度的作用.
通过无水电解液低温电解等离子光
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