镁合金双辊铸轧铸嘴内部熔体流动数值模拟

翁文凭陈琦钟皓邓桢桢闫蕴琪

(苏州有色金属研究院有限公司材料所)

摘要分析了铸嘴内部分流结构对型腔内镁合金熔体流场、温度场产生的影响。采用有限差分的SOL A-V OF法,建立镁合金双辊铸轧立板过程中流动区域的三维流场与温度场耦合模型,在相同的铸轧立板条件下(前箱液面高度、前箱熔体温度固定),数值模拟了不同形状的铸嘴型腔结构对熔体流动速度及温度分布的影响。模拟结果表明,分流块的大小、形状及位置对温度场及流动场影响显著,采用小尺寸、多数量的分流块将有利于在铸嘴型腔内形成均匀的流动场和温度场。通过工艺试验,验证了模拟结果,根据模拟结果改进了铸嘴内部结构,使金属熔体流场、温度场分布均匀,获得了高质量的镁合金铸轧板材。

关键词镁合金;双辊铸轧;铸嘴分流结构;数值模拟

中图分类号T G146.2+2;O242.2文献标志码A文章编号1001-2249(2008)05-0350-03

镁合金在汽车、航空、电子等行业具有广阔得应用前景,被誉为21世纪的绿色工程材料[1]。目前镁合金薄板带坯制备方法主要有热轧法和挤压法,在制备厚度小于10m m的薄板时,存在工序复杂、成材率低等缺点[2~4]。铸轧技术是替代传统镁合金板带生产工艺的主流趋势[5]。此外,利用双辊铸轧技术制备镁合金板材,显微组织均匀、细小、夹杂物少且分布弥散,有利于提高镁合金板材的力学性能[6~8]。

铸嘴内部结构是铸轧最关键的技术之一,采用尺寸稳定性好和耐久性强的材料,使其出口处金属液熔体速度和温度保持均匀一致,对提高铸轧速度和带坯质量至关重要[9,10]。铸轧工艺对铸嘴结构提出的要求是:金属液通过时流线合理、无死角,金属液应均匀分布于辊缝间,而且金属液传入辊缝的温度也要均匀一致[11]。目前大多数研究是针对轧辊和金属带坯温度场数值模拟及铸轧辊形,也有采用水模拟试验来模拟金属熔体在铸嘴型腔中的流态和速度分布,但较少研究金属熔体在铸嘴型腔中的传热及流动特性[12]。此外,国内镁合金双辊铸轧技术尚处于实验室研究阶段,铸嘴材质及结构形式一般借鉴铝合金铸嘴。由于两者在热物理性能上的差异,导致铸嘴内部分流结构难以满足工艺要求。本课题结合镁合金AZ31的热物特性,采用有限差分SOLA-VOF法,利用计算机数值模拟,研究了镁合金双辊铸轧铸嘴液流分配结构对金属液温度场及流场分布的影响规律,优化铸嘴内部结构。

1铸嘴流场与温度场的数学模型

1.1简化假设

(1)镁液具有良好的流动性,在模拟过程中将金属镁液视为连续不可压缩的牛顿流体。

(2)镁液在流动过程中,金属液表观粘度设置为温度依存模式,模拟过程中将位于液相线和固相线之间的金属液表观粘度按照线性简化设置。

(3)模拟主要针对铸嘴内部的分流结构,将铸嘴出液端至辊缝中心线部分简化为与铸嘴内部一体的流动

收稿日期:2007-12-03

基金项目:江苏省自然科学基金技术人才启动项目(BK2006543);中国铝业公司科技发展基金项目(2005KJ A13)

第一作者简介:翁文凭,男,1978年出生,工程师,苏州有色金属研究院有限公司材料所,江苏苏州(215026),电话:0512-********,E-mail: w w ph or se@https://www.360docs.net/doc/ab8271285.html,

3结论

(1)Ti+B复合盐是一种有效的ZA27合金的变质剂,在不影响抗拉强度大小的前提下,可显著提高ZA27合金的伸长率。当加入量为0.3%时,伸长率达到16%以上。变质剂用量少,使用方便,效果稳定。

(2)生产条件下ZA27合金的各项力学性能达到锡青铜制造滑动摩擦耐磨件的性能水平。

参考文献

[1]杨勇勤,熊亚举,陈启超.锌合金成型汽车灯壳模具技术[J].特种

铸造及有色合金,2005,25(11):701-702.

[2]倪锋,龙锐.Zn-Al合金先共晶相的形核与生长特性[J].特种铸造

及有色合金,2001,21(3):1-3.

[3]谢敬佩,王文炎.ZnAl27合金基复合材料高温蠕变性能的研究

[J].特种铸造及有色合金,2001(2):65-67.

[4]陈体军,郝远.ZA27合金的微观组织[J].中国有色金属学报,

2002,12(2):294-299.

[5]赵玉珍,高庆.稀土、钛变质ZA27合金的组织与性能的研究[J].铸

造,2003,52(7):484-487.

[6]施忠良,顾明元.Ce对ZA27合金组织和性能影响的研究[J].上

海交通大学学报,1996(2):93-97.

(编辑:刘卫)

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计算机应用技术特种铸造及有色合金2008年第28卷第5期

区域,周边材质均为保温材料,由此引起铸轧区金属液温度与实际情况产生的差异忽略,而主要考虑流动区域温度场分布均匀情况。1.2 控制方程

镁液在铸嘴中的流动过程属于带有自由表面粘性不可压缩非稳态流动,采用有限差分SOLA -V OF 法对流动过程进行数值模拟,描述流动过程的方程有:

连续性方程(质量守恒方程):

5u 5x +5v 5y +5w 5z

(1)

动量守恒方程(N -S 方程):

5u 5t +u 5u 5x +v 5u 5y +w 5u 5z =-1Q 5p 5x +g x +C 52u 5x 2+52u 5y 2+52u 5z 2(2)

5v 5t +u 5v 5x +v 5v 5y +w 5v 5z

=-1Q 5p 5y +g y +C 52v 5x 2+52v 5y 2+

52v 5z 2

(3)

5w 5t +u 5w 5x +v 5w 5y +w 5w

5z =-15p +g z +C 52

w 5x 2+52

w 5y 2+52

w 5z

2(4)

式中,u 、v 、w 为速度矢量在坐标系中x 、y 、z 方向上的

分量;p 为压力;Q 为高温镁合金液密度;g x 、g y 、g z 为重力加速度;C 为动力粘度系数。

采用体积函数法跟踪自由表面移动时,还需要求解F 函数方程:

5F 5t +u 5F 5x +v 5F 5y +w 5F 5z

=0(5)

能量方程

5T 5t +u 5T 5x +v 5T 5y +w 5T

=A 52

T 5x 2+52

T 5y 2+52

T 5z

+$L (6)式中,A 为热扩散系数,A =K /Q c p ,其中,c p 为比热容,K 为导热系数;$L 为凝固潜热。1.3 流动区域简化

在铸轧过程中,金属液从前箱到铸嘴及辊缝中心线的流动区域简图见图1。在实际生产中,前箱液面在一定范围内波动,在模拟中简化为液面高度恒定。

图1 前箱、铸嘴及铸轧区流动区域示意图

1.4 初始条件及边界条件1.4.1 铸嘴入口初始条件确定

当前箱液面高度恒定后,取辊缝中心线建立势能坐标原点,金属液在不同势能面流动状态符合伯努力方程:

p 0+Q gh 0+

12Q v 20=p 1+Q gh 1+12

Q v 2

1(7)

取金属液面于前箱与铸嘴接口处为研究对象。金

属液在前箱液面处,压力值p 0取大气压,此时忽略金属液从流槽进入前箱时的液面波动,速度值v 0为0,在该坐标系下,h 0=H ;P 1为流动处的压力;v 1为流动处的速度。

在双辊铸轧流动场及温度场计算机模拟仿真研究

中,金属液入口初始条件可以选择为恒定压力或者恒定入口速率[13~15]

。铸轧过程中金属液进入铸嘴达到铸轧区时,其铸嘴入口速度由前箱液面高差产生的静压力

驱动。当金属液充满铸轧区后,铸嘴内部金属液压强高于大气压,因此在铸嘴入口处金属液速度会发生变化,整个流场区域金属液依靠恒定压强驱动其流动。在模拟过程中,取铸嘴入口金属液压力初始条件为p 1:

p 1=p 0+Q g h 0

(8)

1.4.2 边界条件的确定

在流动区域内铸嘴内表面及铸轧辊面,镁熔体边界选取边界无滑移情况,则界面流体速度为0。1.4.3 其他初始条件

前箱液面高度:5cm (前箱液面与铸轧中心线高度差);材料为AZ31,其固相线为595e ,液相线为632e ,密度为1158g /cm 3(液相线以上时);初始温度为700e ;表观粘度设置为温度依存关系,具体取值如下:熔液温度>632e 时,取为0101Pa #s,熔液温度在595e ~632e 范围内,表

观粘度取为0105~0102Pa #s 范围内线形插值;重力加速度为918m /s 2。1.4.4 流动区域选取

图2为数值模拟流动区域。实际工艺中,金属液流经铸嘴,到达铸轧区,通过辊缝中心线完成铸轧过程。在模拟过程中,选取铸嘴及铸轧区作为流动区域,考察镁液在此区域内的流动场及温度场分布规律。

图2 数值模拟流动区域简图

351

镁合金双辊铸轧铸嘴内部熔体流动数值模拟翁文凭等

2 数值模拟结果分析及工艺试验验证

图3为镁合金熔体在铸嘴内部流动传热后温度场数值模拟结果,其模拟对象为图2所示分流结构,工艺条件为模拟初始条件。从图3中可以看出,温度场分布中,金属液在铸轧区中间区域的温度在697e 左右,而边部金属液温度在687e 左右,中间区域温度高出边部温度10e (由于假设流动区域接触介质均为保温材料,忽略铸轧区中金属液与轧辊之间的热传导,因此温度场数值将远高于实际工艺,但是区域温度之间的分布规律

是一致的)。模拟结果表明,在这种液流分配结构下,铸嘴内部金属液流速很不均匀,铸嘴中部流速较大,而边部流速较小,因此导致铸嘴内部金属液温度场区域温差很大,呈现出中部金属液温度高于边部的规律。而图3c 为相似条件下镁合金铸轧工艺试验立板过程中出现的一段板坯,在实际工艺试验中,由于铸嘴内部金属液区域温度差异较大,在铸轧区内金属液中部温度高于边部,导致板带边部已经成形,但中部金属液温度仍处于两相区之间,难以成形。试验结果验证了模拟结果的可

信性。

(a)流动区域温度场(b)优化分流结构后

(c)工艺试验结果(d)优化分流结构后工艺试验结果

数值模拟结果

图3 数值模拟结果及工艺试验结果

为了优化铸嘴内部分流结构,获得一个熔体流动速度分布均匀的流动场,从而使铸嘴出口处金属液速度和温度保持均匀一致,将铸嘴内部分流块的形状和位置做了很多调整,并利用计算机模拟相似工况条件下熔体的流动场和温度场。通过模拟结果,发现减少分流块几何尺寸,增加其数量,设置合理的位置后,铸嘴内部熔体流动场和温度场达到分布均匀的效果。

图3b 是优化铸嘴内部分流结构后,计算机数值模拟流动区域内温度场分布的结果。可以看出,铸嘴内部熔体温度场分布相当均匀,在铸轧区内垂直于铸轧方向上,区域温度之间差值小于2e 。因此,可知当减少分流块几何尺寸,增加其数目,并设置合理位置后,铸嘴内部熔体流动均匀,区域温度差异较小。特别在铸轧区垂直于铸轧方向上,金属液温度分布均匀,有利于后续金属液铸轧成形。图3d 是优化铸嘴分流结构后工艺试验结果,可以看出,采用图3b 所示优化分流结构后,制备出成形良好的镁合金铸轧板坯,验证了模拟结果。

3 结论

(1)铸嘴内部分流结构对镁合金熔体流场及温度场分布影响显著,减小分流块几何尺寸,增加其数目,设置合理位置后,可以获得流速均匀、温度一致的流动场,从而使铸嘴出口处金属液熔体速度和温度保持均匀一致,有利于提高后续镁合金铸轧板坯质量。

(2)采用计算机数值模拟方法,研究镁合金铸轧工艺中铸嘴内部分流结构对熔体流动及温度分布规律,可以优化分流结构,指导实际工艺。

参考文献

[1] 李元元,陈卫东,刘英,等.镁合金的发展动态与前景展望[J ].特种

铸造及有色合金,2004(11):14-18.

[2] 陈振华.变形镁合金[M ].北京:化学工业出版社,2005.

[3] 陈维平,詹美燕,陈宛德,等.变形镁合金的塑性加工技术研究及展

望[J].特种铸造及有色合金,2007,27(1):40-43.

[4] 王祝堂.镁板材轧制工艺及性能[J].有色金属加工,2004,33(3):8-11.[5] ALLEN R V,EAST D R,JOH NSON T J,et al.M agnesium alloy

sheet produced by tw in roll casting [C].2001T M S Ann ual M eet -in g,New Orlean s,L ouisian a,USA,2001.

[6] 翁文凭,闫蕴琪,陈琦,等.双辊铸轧镁合金板坯微观组织特征[J].

特种铸造及有色合金,2007,27(11):827-828.

[7] 张颂阳,耿茂鹏,谢水生,等.铸轧半固态镁合金组织特征[J ].特种

铸造及有色合金,2006,26(7):430-432.

[8] 张文玉,刘先兰,陈振华,等.轧制路径对AZ31镁合金薄板组织性

能的影响[J].特种铸造及有色合金,2007,27(9):716-719.

[9] 唐俊龙,黄明辉,杨安全.基于ANSYS 的铸嘴流体耦合场三维有限

元仿真分析[J ].铸造设备研究,2003,8(4):23-26.

[10] 李向宇.铝铸轧机常用铸嘴结构和材质[J].轻合金加工技术,

1998,26(10):17-20.

[11] 孙斌煜.板带铸轧理论与技术[M ].北京:冶金工业出版社,2002.[12] 彭成章,胡忠举,黄明辉.铝熔体在铸嘴型腔中的传热及凝固现象

分析[J].中南工业大学学报(自然科学版),2003,34(1):70-73.

[13] 周英,黄明辉,钟掘.铝铸轧流场有限元模拟计算方案合理性的探

讨[J].中国有色金属学报,2005,15(7):1100-1106.

[14] 邓圭玲,段吉安,钟掘.双辊铸轧铸嘴内部铝液流动的三维数值仿

真[J].中南大学学报(自然科学版),2005,36(4):615-620.

[15] SARIOGLU K,YILDIZBAYRAK G,DUNDAR https://www.360docs.net/doc/ab8271285.html,pu ter

simulation of metal feeding us ed in tw in roll cas tin g[A].Light M etals 2000[C].Warren Dale:TM S,2000.

(编辑:张正贺)

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特种铸造及有色合金 2008年第28卷第5期

Sheet during Accumulative Rolling-bonding Chen W eiping,Yang D ongyu,Zhan M eiyan(Scho ol of Mechanical and Automo tive Engineering,South China Univer sity of T echno log y,Guangzhou,China)2008, 28(5)338~341

Abstract Effects of ro lling tem peratur e and cy cle num-bers on micr ostructure and pro perties of the AZ31 magnesium sheets during accumulative ro lling-bonding (ARB)w ere investigated,and the mechanism of g rain refinem ent in AZ31mag nesium alloy dur ing ARB w as described.It is found that the average grain size is de-creased w ith the temper ature incr easing from250e to 400e after the first cycle per io d in ARB.T he AZ31 sheets w ith average g rain size of113L m and elonga-tion o f2512%as w ell as tensile streng th o f300M Pa can be obtained by ARB at400e w ith50%thickness reduction per pass after the seco nd recycle during ARB.

Key Words:Accumulative Rolling-bonding(ARB), AZ31Magnesium Alloy,Grain Refinement,Micro-structure

Microstructure and Magnetostrictive Properties of Mel-t spun Fe-Ga Alloy Ribbons Ding Yutian,Liu Fenxia, H u Yong,Zhang Ya nlong(State Key Laboratory of Gansu Advanced Non-fer rous Metal Mater ials, Lanzhou U niversity o f T echno logy,Lanzho u,China) 2008,28(5)341~343

Abstract Effects of different rolling speeds including 12,15and20m/s and differ ent compositions o n the micro structure and magneto strictive proper ties of Fe-Ga allo y prepared by melt-spun method have been ex-am ined.The results reveal that the m icrostructur e and magneto strictive pr operties of the alloy s are closely re-lated to the composition and cooling rate during melt-spun process.T he maximum magneto strictive pro per-ties of Fe83Ga17reaching up to615@10-5can be ob-tained w ith a co oling rate of12m/s.T he X-ray dif-fraction indicates that the m icrostructur es of all allo y ribbons ar e com posed of Fe so lid solution.The ribbon observatio n reveals that the cry stal along thick direc-tion of ribbons exhibits orientation to some ex tent. The mag netostriction of the ribbons is related to the hig h lattice distor tion and shape anisotro py.

Key Words:Fe-Ga Alloy,Mel-t spun,Lattice Distor-tion,Magnetostriction

Effects of Homogenization Treatment on Microstructure and Properties of7B50Aluminum Alloy Li Guofeng1,2, Zha ng Xinm ing1,Zhu Hangfei1,Li Penghui1(1. School of M aterials Science and Eng ineer ing,Central South U niv ersity,Changsha,China; 2.Department of M echanical and Electric Engineering,Chang sha U-niversity,Changsha,China)2008,28(5)344~347 Abstract Effects o f hom ogenization treatment on m-i crostructure and pr operties of7B50aluminum allo y have been investigated by optical microscope(OM),XRD(X-ray diffr actio n)and SEM(scanning electro n microscope).T he results indicate that the co ntent o f residual un-equilibrium eutectic phase w ith m ore un-i fo rm distribution w hich is mainly composed of imm is-cible Fe-eutectic phase in the alloy homo genized by tw o-step ho mog enizatio n tr eatment is m uch less than that homo genized by one-step ho mog enizatio n treat-ment.Co mpar ed w ith that precipitated from the alloy homog enized by one-step homo genization treatment, the secondary phase Al3Zr particle precipitated fr om the allo y ho mog enized by tw o-step ho mog enizatio n treatment exhibits mo re dispersive and uniform distr-i butio n w ith slig ht coarse,w hich is helpful to the im-pro vement o f strength of the alloy.

Key W ords:Homogenization Treatment,7B50Alloy, Microstructure and Properties

Sal-t composite Modification on ZA27C ast Alloy Zhou Dianw u1,2,Liu Jinshui3,Shu Zhen2(1.State Key La-bo rator y of A dvanced Design and M anufacturing for Vehicle Bo dy,H unan U niversity,Chang sha,China;

2.Schoo l of M echanical and Automo bile Engineering,

H unan University,Chang sha,China; 3.School o f M aterials Science and Engineering,H unan Univers-i ty,Chang sha,China)2008,28(5)348~350

Abstract T he pr ocessing parameters of salt-composites mo dification on ZA27alloy have been determined, w hich w as v erified by practical pr oduct.T he results indicate that the T i+B mixed m odification can re-markably improve the elongation of ZA27under the co ndition of no n-deterior ating tensile streng th,which is a effective modifier.T he pr oduction verifies that the mechanical pr operties of ZA27alloy can approach to that o f the bronze parts.

Key Words:ZA27Alloy,Sal-t composite,Modification Numerical Simulation of Molten Magnesium Flow in Feed Tip Nozzles of Twin-roll Casting W eng W enping, Chen Qi,Zhong Hao,Deng Zhenzhen,Yan Yunqi (Suzho u N onferrous M etals Research Institute, Suzho u,China)2008,28(5)350~352

Abstract Effects of the config uration o f feed tip nozzle on flo w field and tem perature field in tw in-ro lling cast-ing str ip o f magnesium allo y melt in cav ity w ere de-scribed.Based on the SOLA-V OF finite differential metho d,the co upled mo del of flow field w ith tempera-ture field in tw in-rolling casting strip of mag nesium a-l loy melt has been established to simulate the effects o f different no zzle cav ity structure o n flow v elo city of the magnesium m elt and tem perature distr ibution in m ag-nesium melt under the same initial condition including the same height and tem perature of the m olten m ag ne-sium alloy in fr ont box.The results reveal that de-creasing the size and incr easing num bers o f the spacer are helpful to obtaining uniformly distributed flow field and temperatur e field in cavity o f feed tip no zzle. The results are w ell in agreement w ith sim ulated

ones,and the mag nesium alloy strip w ith desirable quality can be pro duced based on simulated results modifying the structur e of feed tip nozzle.

Key Words:Magnesium Alloy,Twin-rolling C asting, C onfiguration of Feed Tip Nozzle,Numerical Simulation Modeling of Non-isothermal Dendrite Growth in Pb-Sn Alloy Hao Lim ei1,Chen Zhi2(1.Department of Basic Co ur se,Xi'an U niversity of Science and T echno logy, Xi'an,China; 2.School of Science,Northw estern Poly technical Univer sity,Xi'an,China)2008,28(5) 353~356

Abstract The m odeling of non-isotherm al dendrite grow th in Pb-Sn alloy w as conducted based on the phase field metho d to visualize the evo lution of inter-face mor pholog y of dendrite and to examine the effects of phase param eters o n it.T he results indicate that the dendr ite mo rpholo gy is dependent on the under-coo led deg ree,co upled parameters and anisotropy va-l ue.T he trapped m elt packets and side branches can be greatly suppressed by an ant-i trapping current.Fur-thermor e,the relationship betw een anisotropy and dendrite tip v elo city w as described.

Key Words:Phase Field Method,Pb-Sn Alloy,Non-isothermal,Dendrite Growth,Tip Velocity,Ant-i trap-ping Current,Anisotropy

Numerical Simulation of Filling of Magnesium Alloy Steering Wheel in Die Casting Chang H uanhua n,Long Siyuan,Cao H a nxue,Du Yong(School of M echanical Eng ineer ing,Chong qing U niv ersity,Chongqing,Ch-i na)2008,28(5)357~358

Abstract T he m ould for mag nesium allo y steering w heel can be desig ned by the CAE softw are w hich can predict potential defect locatio n in die casting.Based on analy sis of simulated results,the die casting die w as mo dified and optim ized.T he results sho w that the defects in the die casting m ag nesium steering w heel can be g reatly eliminated by using modified pro cess,im pro ving the quality of the castings.

Key Words:Numerical Simulation,Die Casting,De-fects

Preparation of Sem-i solid A356Alloy Slurry with Trave-ling Wave Stirring Zhong Rongm a o,M a o W eim in, Zha o Zhenduo(Schoo l of M aterials Science and Eng-i neer ing,Univer sity of Science and Technolog y Be-i jing,Beijing,China)2008,28(5)359~362

Abstract The bigg er size A356aluminum alloy sem-i solid slurry w ith spherical primary A-A l phase w as pre-pared by low super-heating po uring combining w ith tr av eling w ave electr omagnetic stirring.The effects of pouring temper ature,stirr ing fr equency and stirring pow er on the micro structur e o f sem-i solid A356alum-i num allo y slurry w ere observ ed.It is found that w ith decreasing in po uring tem peratur e,the primary A-Al phase in the sem-i so lid slurry becomes mo re and more round,and the more desir able micr ostructure in the sem-i so lid slurry can be prepared w ith the stirr ing fre-quency equal to or m ore than10H z.With increasing in stirring pow er,the m ore r ound primary A-Al phase can be form ed in the sem-i so lid slurr y,w hich is attr ib-uted to the rosette-like primary A-A l phase in the sem-i so lid A356allo y slur ry intensely subjected to the man-made tem perature fluctuation to result in the root melting of dendr ite.T he fine spheroidized primary A-Al phase can be successfully prepar ed w ith pouring at 620e and stir ring at10H z as w ell as1.72kW.

Key Words:Sem-i solid,A356Alloy,Traveling W ave Electromagnetic Stirring,Low Temperature Pouring, Microstructure

Effects of Technological Parameters on Microstructure of Sem-i solid A-l30Si Alloy Slurry Prepared by Low Su-per-heat Pouring Combining Weak Electromagnetic Stir-ring Zhang Jiatao,Fa n Gang,W ei Chang,Ra n Sha-obing,Zha ng W eijun(Faculty of M aterials and M et-allurg ical Engineering,Kunming U niversity of Science and T echno logy,Kunming,China)2008,28(5)362~ 366

Abstract Effects of techno logical parameter s including po uring tem perature,stirring pow er and stir ring tim e on m icrostructur e of sem-i solid A-l30Si alloy slurry pr epared by low super-heat po uring combining w eak e-lectromag netic stir ring w ere analyzed.The r esults in-dicate that com pared w ith that prepared by conven-tio nal casting,the sem-i so lid A-l30Si alloy slur ry pre-pared by low super-heat pouring co mbing w ith w eak e-lectromag netic stirring ex hibits mo re desirable struc-ture morpholog y,in w hich the minim um and m ax-i mum size o f primary Si can be decreased from16L m to 7L m and from296L m to23L m,respectively,and the average size of pr im ary Si phase can be decreased fr om 13818L m to11149L m,and the allo y w ith m ore un-i fo rm distribution in slurr y becom e mor e and mor e sphero idizatio n.The mo rpholo gy,distr ibution and size of prim ary Si in sem-i so lid A-l30Si alloy slurry ar e deeply dependent on the pouring temperature,stirring po w er and stirr ing time.

Key W ords:Low Super-heat Pouring,Weak Electro-magnetic Stirring,Sem-i solid,A-l30Si Alloy,Micro-structure

Decennial Survey on Foundation and Application of Sem-i solid Processing Yang Yita o,Sha o Gua ngjie, Zha ng Henghua,Xu Luoping(Schoo l of M aterial Sc-i ence and Eng ineering,Shang hai Univer sity,Shang-hai,China)2008,28(5)367~372

Abstract T he fo undation and application of sem-i solid pr ocessing w ere surv ey ed including continuous casting pr ocess,r eheating of billet,the r heolo gical behavior of sem-i solid slurry,die casting pr ocess of sem-i solid slurry,the heat treatm ent of die castings,numerical sim ulation and production o f automobile parts.T he