电磁振荡频率对上引连铸Cu-15Ni-8Sn合金组织及逆偏析的影响  

Effect of Electromagnetic Vibration Frequency on Structure and Inverse Segregation of Cu-15Ni-8Sn Alloy in Up-drawing Continuous Casting

作　　者：钟杰 沈喆 郑天祥[1,2] 唐柑培 林中泽 钟云波 ZHONG Jie;SHEN Zhe;ZHENG Tianxiang;TANG Ganpei;LIN Zhongze;ZHONG Yunbo(School of Materials Science and Engineering, Shanghai University, Shanghai 200444, China;State Key Laboratory of Advanced Special Steel, Shanghai University, Shanghai 200444, China)

机构地区：[1]上海大学材料科学与工程学院,上海200444 [2]省部共建高品质特殊钢冶金与制备国家重点实验室,上海200444

出　　处：《上海金属》2020年第4期88-94,共7页Shanghai Metals

基　　金：十三五国家重点研究发展计划(2016YFB0301401,2016YFB0300401);国家自然科学基金(U1860202,U1732276,50134010,51704193);上海市科委基础研究项目(13JC14025000,15520711000)。

摘　　要：通过在上引连铸Cu-15Ni-8Sn(质量分数,%)合金过程中施加电磁振荡,研究了电磁振荡频率对合金凝固组织及逆偏析的影响。结果表明:当施加的电磁振荡频率为10或30 Hz时,合金的宏观凝固组织发生了柱状晶到等轴晶的转变,微观凝固组织由树枝晶转变为蔷薇状组织;当电磁振荡频率从30 Hz增加到50 Hz时,宏观凝固组织又逐渐转变为柱状晶,微观凝固组织也随之转变为发达的树枝晶。电磁振荡频率为10和30 Hz时形成的等轴晶组织有利于改善合金中Sn元素的逆偏析。电磁振荡使合金熔体中产生往复强制对流,10或30 Hz频率的电磁振荡引起的宽幅往复流动使固液界面前沿温度场和溶质场均匀,有利于形成等轴晶,并促使枝晶折断,形成游离晶,消除定向枝晶通道,从而抑制了逆偏析。而在50或100 Hz频率下,电磁振荡频率过高形成了窄幅往复流动,不能有效折断枝晶、达到细化晶粒的目的,从而减弱了抑制逆偏析的作用。Influence of electromagnetic vibration frequency(EMVF)on the macro/micro structure and inverse segregation of Cu-15Ni-8Sn(mass fraction,%)alloy produced by up-drawing continuous casting was studied by applying an electromagnetic vibration.The results revealed that when the EMVFs were 10 Hz or 30 Hz,the columnar-to-equiaxed transition occurred in the macrostructure,and the dendrite-to-rose-like transition occurred in the microstructure of the alloy.When the EMVF was increased from 30 Hz to 50 Hz,the macrostructure transformed into columnar crystal,and the microstructure transformed into developed columnar dendrites.The equiaxed crystal structure produced at EMVFs of 10 Hz and 30 Hz helped improve the inverse segregation of Sn element in the alloy.The electromagnetic vibration produced reciprocating forced convectionin in the melt.The wide reciprocating flow caused by electromagnetic vibration of 10 Hz or 30 Hz made the temperature field and the solute field at the front of the solid-liquid interface uniform,which was conducive to the formation of equiaxed crystals,to break of the dendrites,to formation of free crystals and to elimination of the oriented dendritic channels,thus suppressing the inverse segregation.While EMVFs were 50 Hz and 100 Hz,the high electromagnetic vibration frequency formed a narrow reciprocating flow,which could not effectively break the dendrites and refine the grains,thus weakening the effect on suppressing the reverse segregation.

关 键 词：电磁振荡 CU-15NI-8SN合金 凝固组织 晶粒细化 逆偏析 

分 类 号：TG1[金属学及工艺—金属学]