电磁铸造
<DIV><P class=zz30 align=left> <SPAN class=blk14>20世纪60年代，前苏联学者Getselev等依据电磁感应原理发明了电磁铸造(Electromagnetic Casting，简称EMC)技术。这一技术一经产生就得到了迅速发展。1969年前苏联已将此技术工程化，用EMC技术制造了<I>ф</I>200-<I>ф</I>500mm的铝合金圆锭，20世纪70年代EMC技术在前捷克斯洛伐克、匈牙利、前民主德国等东欧国家首先得到普及，之后，瑞士、美国等欧美国家相继引进此项技术并将它进一步提高为用计算机控制的自动化生产的水平。我国于20世纪70年代也试生产过铝合金圆锭，80年代也掌握了工业规模的生产技术。电磁铸造首先是在铝合金中取得成功，然后扩展到铜合金，开始只能生产铸锭，现在能够生产具有一定形状的异型件。目前世界许多国家，包括我国，为开发钢的电磁铸造技术投入了大量的人力和财力。</SPAN></P>
<P class=blk18b style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: left" align=left> 1 原理</P>
<P> <SPAN class=blk14>电磁铸造的原理示于图11-1a。当感应器线圈中通过电流密度为<I>J<SUB>0</SUB></I>的交变电流时，产生交变电磁场<I>H</I>，电磁场作用于金属液形成与感应器电流反向的密度为<I>J</I>的感生电流，感生电流与励磁电流相互作用产生磁感应强度<I>B</I>和指向感应线圈内的电磁力<B><SUB><IMG height=19 src="http://www.chmcw.com/upload/news/RCL/13220_wg64hgimage002.gif" width=68 v:shapes="_x0000_i1025"></SUB></B>，这样，金属液在电磁力的侧向约束下呈半悬浮状态。感应器下面的冷却水喷向铸锭，金属液在保持自由表面的状态下凝固，同时，铸造机拖动底模和铸锭向下运动，从而形成连续铸造过程。为了获得侧面垂直的半悬浮金属液柱，增设屏蔽罩使液柱侧面的电磁压力分布接近液柱上的静压力分布，如图11-1b所示。另外，屏蔽罩还可以抑制电磁力对金属液的过度搅拌，达到稳定液柱的目的。</SPAN></P>
<P align=center><IMG height=240 src="http://www.chmcw.com/upload/news/RCL/13220_4iduwaimage004.jpg" width=553 v:shapes="_x0000_i1026"> </P>
<P class=style1 align=center>图1 电磁铸造的基本原理</P>
<P class=style1 align=center>a) 电磁铸造原理 b) 电磁压力分布</P>
<P> <SPAN class=blk14>从上述简单分析可知，在电磁铸造中电磁场通过电磁力使导电金属液形成一定外轮廓形状，同时引起流动。另一方面，在磁场中运动的导体即金属液，反过来又引发电场。因此，电磁铸造是电场、磁场和速度场相互耦合作用的过程。因此，要从理论上分析EMC技术，需要联立求解描述电磁场规律的Maxwell 方程和描述流速场规律的Navier-Stokes方程。但是在多数情况下，忽略流速场来求解电磁场，再以所得电磁力来推测金属液流速场。Maxwell的基本方程为：</SPAN></P>
<TABLE class=12zi width="100%" border=0>
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<TH scope=col width="51%"><SPAN class=blk14><IMG height=32 src="http://www.chmcw.com/upload/news/RCL/13220_rhdoglimage006.gif" width=73></SPAN></TH>
<TH scope=col width="49%"><SPAN class=blk14>(1)</SPAN></TH></TR>
<TR>
<TD>
<DIV align=center><SUB><IMG height=17 src="http://www.chmcw.com/upload/news/RCL/13220_ttcztgimage008.gif" width=65></SUB></DIV></TD>
<TD>
<DIV align=center>(2)</DIV></TD></TR>
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<TD>
<DIV align=center><SUB><IMG height=15 src="http://www.chmcw.com/upload/news/RCL/13220_nbbk51image010.gif" width=58></SUB></DIV></TD>
<TD>
<DIV align=center>(3)</DIV></TD></TR>
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<TD>
<DIV align=center><SUB><IMG height=20 src="http://www.chmcw.com/upload/news/RCL/13220_m8k2flimage012.gif" width=48></SUB></DIV></TD>
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<DIV align=center>(4)</DIV></TD></TR>
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<TD colSpan=2> 式中<I>E </I>—— 电场强度 (V/m)；<I>H </I>—— 磁场强度 (A/m)；<I>J </I>—— 电流密度 (A/m<SUP>2</SUP>)；<I>B </I>—— 磁感应强度 (T)；<I>t </I>—— 时间 (s)。</TD></TR>
<TR>
<TD class=blk14 height=38>
<P> 忽略金属液流动时的欧姆定律为：</P></TD>
<TD><SUB><IMG height=19 src="http://www.chmcw.com/upload/news/RCL/13220_fw7ikaimage014.gif" width=51></SUB> (5)</TD></TR>
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<TD colSpan=2>
<P> </P>
<P>|||</P>
<P> 式中 <I>σ</I>—— 金属液的电导率(1/Ωm)。</P></TD></TR>
<TR>
<TD class=blk14 colSpan=2> 在EMC边界条件下联立求解式(1)～式(5)，求得电流密度<I>J</I>和磁感应强度。单位体积内的电磁力可由下式计算：</TD></TR>
<TR>
<TD>
<DIV align=center><SUB><IMG height=19 src="http://www.chmcw.com/upload/news/RCL/13220_ookvh0image016.gif" width=68></SUB></DIV></TD>
<TD>
<DIV align=center>(6)</DIV></TD></TR>
<TR>
<TD class=blk14 colSpan=2><SPAN class=blk14> 将式(7-107)带入式(7-111)，<I>μ</I>为磁导率，通过矢量运算，得如下电磁力的表达式：</SPAN></TD></TR>
<TR>
<TD>
<DIV align=center><SPAN class=blk14><SUB><IMG height=24 src="http://www.chmcw.com/upload/news/RCL/13220_8lwlhiimage018.gif" width=228></SUB></SPAN></DIV></TD>
<TD>
<DIV align=center><SPAN class=blk14>(7)</SPAN></DIV></TD></TR>
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<TD class=blk14 colSpan=2><SPAN class=blk14>式中右端第一项为旋转力，对熔体起搅拌作用；第二项为非旋转力，起因于电磁压力：</SPAN></TD></TR>
<TR>
<TD>
<DIV align=center><SPAN class=blk14><SUB><IMG height=47 src="http://www.chmcw.com/upload/news/RCL/13220_es5wgzimage020.gif" width=67></SUB></SPAN></DIV></TD>
<TD>
<DIV align=center><SPAN class=blk14>(8)</SPAN></DIV></TD></TR>
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<TD class=blk14 colSpan=2><SPAN class=blk14> 其中<I>p<SUB>m</SUB></I> 为液柱表面的磁压力，<SUB><IMG height=24 src="http://www.chmcw.com/upload/news/RCL/13220_hosnjqimage022.gif" width=25></SUB>为通过液柱表面的磁感应强度的有效值。式(7)右端第一项为单位体积旋转力，大小为<I>F</I><SUB>1</SUB>，第二项为单位体积非旋转力，大小为<I>F</I><SUB>2</SUB>，它们之间满足如下关系：</SPAN></TD></TR>
<TR>
<TD>
<DIV align=center><SPAN class=blk14><SUB><IMG height=47 src="http://www.chmcw.com/upload/news/RCL/13220_qneafnimage024.gif" width=53></SUB></SPAN></DIV></TD>
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<DIV align=center><SPAN class=blk14>(9)</SPAN></DIV></TD></TR>
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<TD colSpan=2> 式中 <I>L</I>—— 铸锭横截面尺寸；<I>δ</I>—— 电流趋肤深度。<SUB><IMG height=27 src="http://www.chmcw.com/upload/news/RCL/13220_1xue6himage026.gif" width=104></SUB></TD></TR>
<TR>
<TD class=blk14 colSpan=2><SPAN class=blk14> 可知电流频率<SUB><IMG height=17 src="http://www.chmcw.com/upload/news/RCL/13220_gtog8bimage028.gif" width=12></SUB>越大电磁搅拌作用就越小。电磁铸造中一般要求<I>L</I>/δ≥10。在电磁铸造中忽略液柱内的流动造成的动压力时，液柱中存在如下力的平衡关系：</SPAN></TD></TR>
<TR>
<TD>
<DIV align=center><SPAN class=blk14><SUB><IMG height=41 src="http://www.chmcw.com/upload/news/RCL/13220_dyybk6image030.gif" width=103></SUB></SPAN></DIV></TD>
<TD>
<DIV align=center><SPAN class=blk14>(10)</SPAN></DIV></TD></TR>
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<TD colSpan=2><SPAN class=12zi> 式中 <SUB><IMG height=18 src="http://www.chmcw.com/upload/news/RCL/13220_wkpqqqimage032.gif" width=12></SUB> —— 金属液密度(g/cm)；g—— 重力加速度(cm/s<SUP>2</SUP>)；h —— 金属液柱高度(cm)；<SUB><IMG height=17 alt=* src="http://www.chmcw.com/upload/news/RCL/13220_bgcddhimage038.gif" width=13></SUB> —— 金属液柱表面张力(N/cm)；r —— 金属液柱曲率半径(cm)。</SPAN></TD></TR></TBODY></TABLE>
<P> <SPAN class=blk14>在电磁铸造中铸锭尺寸都较大，式(10)右端第二项可以忽略。估算形成一定的金属液柱高度所需要的磁感应强度时，式(10)是很有用的。<BR> 从上可知，金属液具有导电性是实现电磁铸造的必要条件，在此基础上金属密度越小越容易实现电磁铸造过程。</SPAN></P>
<P class=blk18b align=left> 2 电磁铸造工艺<BR> <SPAN class=blk14>图2为电磁铸造装置示意图，它是由中频电源，感应线圈，屏蔽罩，冷却水箱，底模，浇注系统和铸造机组成。铸造机实际是可调速的向上和向下运动的机构，浇注系统一般由中间包和可控浇口塞组成。感应器是用截面为长方形的中空的纯铜绕制而成，中空是为通水冷却所必需。感应器一般做成上下倾斜的。这是为了使金属液柱上方受的磁压力小于下方，与屏蔽罩协调改善金属液柱形状和使其稳定。屏蔽罩用不锈钢绕制而成，因铸造过程中屏蔽罩也需要散热，设法在其表面流水冷却。</SPAN>
<P class=blk14> 铸造过程如下：首先将底模边缘的上平面移动到感应器半高处，然后启动中频电源；浇注；当液面高度达一定值时固定输出功率，喷水冷却，底模以一定速度向下移动。</P>
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><IMG height=297 src="http://www.chmcw.com/upload/news/RCL/13220_u2hdyfimage042.jpg" width=328 v:shapes="_x0000_i1045"> </P>
<P class=style1 style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center>图2 电磁铸造装置</P>
<P> <SPAN class=blk14>电磁铸造成败的关键，是使金属液柱稳定并使其高度保持一定。为达此目的，合理选择工艺参数是十分重要的。最重要的参数有：电流频率，电流强度，铸造速度，喷水冷却强度。提高电流频率可降低金属液柱中电磁搅拌引起的流动，但随着电流频率的增大感应加热作用迅速增大，不利于提高铸造速度，无谓地浪费电能。在铝合金的电磁铸造中，电流频率一般取2000～3000Hz。电流强度是根据所需要的金属液柱高度而定，金属液柱高度过低，金属液柱顶面的边缘向内收缩，铸造过程不易控制；金属液柱过高，也造成电能的浪费。金属液柱高度一般控制在30～50mm是适当的，这时所需要的电流强度为3500～5000A。铸造速度随喷水冷却强度而变，目前一般采用循环水喷水冷却，冷却强度的提高受到制约，因此铝合金的电磁铸造速度一般只能达到60～100mm/min。</SPAN><BR> </P>
<P><SPAN class=blk14>|||</SPAN></P>
<P><SPAN class=blk14> 电磁铸造成败的另一个关键，是浇注速度和铸造速度(拉坯速度)相协调，使金属液柱高度保持不变。为达此目的一般采用以液面高度传感器反馈控制浇注速度的办法。<BR> 浇注温度和冷却水温度的变化，电源的波动以及中间包中的金属液量的变化，也都引起铸造过程的不稳定，因此大规模先进的电磁铸造生产，已实现了计算机控制的全自动化生产，并且一机同时拉多锭(3～5锭)。表11-1是一组典型的电磁铸造工艺参数。 </SPAN></P>
<P class=style1 style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center>表1 典型的铝合金电磁铸造工艺参数</P>
<TABLE class=table1 borderColor=#b5dba2 cellSpacing=0 cellPadding=0 width="75%" align=center border=1>
<TBODY>
<TR>
<TD vAlign=top width="16%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center>铸锭尺寸/mm</P></TD>
<TD vAlign=top width="16%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center>感应圈电流/A</P></TD>
<TD vAlign=top width="16%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center>感应圈电压/V</P></TD>
<TD vAlign=top width="16%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center>频率 / Hz</P></TD>
<TD vAlign=top width="13%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center>功率 / kW</P></TD>
<TD vAlign=top width="23%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center>金属液柱高度/mm</P></TD></TR>
<TR>
<TD width="16%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center>300×1100</P></TD>
<TD width="16%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center>5000</P></TD>
<TD width="16%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center>55</P></TD>
<TD width="16%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center>2000</P></TD>
<TD width="13%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center>40<SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">-50</P></SPAN></TD>
<TD width="23%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center>55</P></TD></TR>
<TR>
<TD width="16%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><I>φ</I>340</P></TD>
<TD width="16%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center>4970</P></TD>
<TD width="16%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center>29</P></TD>
<TD width="16%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center>2000</P></TD>
<TD width="13%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center>35</P></TD>
<TD width="23%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center>29</P></TD></TR>
<TR>
<TD width="16%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center>482×1143</P></TD>
<TD width="16%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><SPAN style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">—</P></SPAN></TD>
<TD width="16%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center>40<SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">-50</P></SPAN></TD>
<TD width="16%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center>2400<SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">-3000</P></SPAN></TD>
<TD width="13%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><SPAN style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">—</P></SPAN></TD>
<TD width="23%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center>38</P></TD></TR>
<TR>
<TD width="16%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><I>φ</I>345</P></TD>
<TD width="16%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center>3400<SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">-3800</P></SPAN></TD>
<TD width="16%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><SPAN style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">—</P></SPAN></TD>
<TD width="16%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center>2500</P></TD>
<TD width="13%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><SPAN style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">—</P></SPAN></TD>
<TD width="23%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><SPAN style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">—</P></SPAN></TD></TR></TBODY></TABLE>
<P class=blk18b style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: left" align=center> 3 铸造组织和性能<BR> <SPAN class=blk14>在电磁铸造中，铸锭是在保持液态金属自由表面的情况下凝固，因此铸锭表面光滑，几乎接近镜面。由于凝固前沿始终存在电磁搅拌作用，凝固又是在直接喷水冷却的条件下快速完成，所以凝固组织致密，几乎无偏析。另外，喷水冷却部位在金属液柱底部，宏观上看凝固是自下而上进行，因此凝固组织接近定向凝固的组织，横截面易形成等轴晶。图3是电磁铸造和金属型中铸造的铝合金凝固组织的比较。</SPAN>
<P align=center><IMG height=146 src="http://www.chmcw.com/upload/news/RCL/13220_4vm2tgimage044.jpg" width=154 v:shapes="_x0000_i1046"></P>
<P align=center>a) b)</P>
<P align=center><SPAN class=style1>图3 两种铸造方法凝固组织比较<BR>a) 电磁铸造 b) 金属型铸造</SPAN><BR>
<P class=blk14> 材料的力学性能也得到明显的改善，特别是材料的压力加工性能得到大幅度的提高。表2和表3是上述两种铸造方法所得材料力学性能的比较。</P>
<P class=style1 style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center>表2 金属型铸造的铝合金力学性能</P>
<DIV align=center>
<TABLE class=table1 borderColor=#b5dba2 cellSpacing=0 cellPadding=0 width="100%" border=1>
<TBODY>
<TR>
<TD width="17%" rowSpan=9>
<P>模 铸</P></TD>
<TD width="13%" rowSpan=2>
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center>方 向</P></TD>
<TD width="23%" rowSpan=2>
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center>位 置</P></TD>
<TD width="23%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center>抗拉强度σ<SUB>b</SUB>/</P></TD>
<TD width="24%" rowSpan=2>
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center>断后伸长率δ(%)</P></TD></TR>
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<TD width="23%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">MPa</P></SPAN></TD></TR>
<TR>
<TD width="13%" rowSpan=4>
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center>纵 向</P></TD>
<TD width="23%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">1</P></SPAN></TD>
<TD width="23%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">109.18</P></SPAN></TD>
<TD width="24%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">7.75</P></SPAN></TD></TR>
<TR>
<TD width="23%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">2</P></SPAN></TD>
<TD width="23%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">116.98</P></SPAN></TD>
<TD width="24%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">11.38</P></SPAN></TD></TR>
<TR>
<TD width="23%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">3</P></SPAN></TD>
<TD width="23%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">122.25</P></SPAN></TD>
<TD width="24%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">7.5</P></SPAN></TD></TR>
<TR>
<TD width="23%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center>平 均</P></TD>
<TD width="23%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">116.24</P></SPAN></TD>
<TD width="24%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">8.88</P></SPAN></TD></TR>
<TR>
<TD width="13%" rowSpan=3>
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center>横 向</P></TD>
<TD width="23%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center>表 面</P></TD>
<TD width="23%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">128.60</P></SPAN></TD>
<TD width="24%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">9.80</P></SPAN></TD></TR>
<TR>
<TD width="23%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center>中 心</P></TD>
<TD width="23%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">125.40</P></SPAN></TD>
<TD width="24%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">10.70</P></SPAN></TD></TR>
<TR>
<TD width="23%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center>平 均</P></TD>
<TD width="23%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">127.00</P></SPAN></TD>
<TD width="24%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">10.25</P></SPAN></TD></TR></TBODY></TABLE></DIV>
<P class=style1 style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center>表3 电磁铸造的铝合金力学性能</P>
<DIV align=center>
<TABLE class=table1 borderColor=#b5dba2 cellSpacing=0 cellPadding=0 width="100%" border=1>
<TBODY>
<TR>
<TD width="12%" rowSpan=11>
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center>电磁铸造</P></TD>
<TD width="9%" rowSpan=2>
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center>方 向</P></TD>
<TD colSpan=2 rowSpan=2>
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center>位 置</P></TD>
<TD colSpan=2>
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center>抗拉强度σ<SUB>b</SUB>/</P></TD>
<TD width="19%" rowSpan=2>
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center>断后伸长率δ(%)</P></TD>
<TD width="22%" rowSpan=2>
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center>断面收缩率ψ(%)</P></TD></TR>
<TR>
<TD colSpan=2>
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">MPa</P></SPAN></TD></TR>
<TR>
<TD width="9%" rowSpan=6>
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center>纵 向</P></TD>
<TD colSpan=2>
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">1</P></SPAN></TD>
<TD colSpan=2>
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">162.8</P></SPAN></TD>
<TD width="19%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">16.2</P></SPAN></TD>
<TD vAlign=top width="22%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">32.4</P></SPAN></TD></TR>
<TR>
<TD colSpan=2>
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">2</P></SPAN></TD>
<TD colSpan=2>
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">166.7</P></SPAN></TD>
<TD width="19%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">19.0</P></SPAN></TD>
<TD vAlign=top width="22%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">34.9</P></SPAN></TD></TR>
<TR>
<TD colSpan=2>
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">3</P></SPAN></TD>
<TD colSpan=2>
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">162.1</P></SPAN></TD>
<TD width="19%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">25.0</P></SPAN></TD>
<TD vAlign=top width="22%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">38.9</P></SPAN></TD></TR>
<TR>
<TD colSpan=2>
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">4</P></SPAN></TD>
<TD colSpan=2>
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">159.9</P></SPAN></TD>
<TD width="19%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">17.5</P></SPAN></TD>
<TD vAlign=top width="22%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">34.9</P></SPAN></TD></TR>
<TR>
<TD colSpan=2>
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">5</P></SPAN></TD>
<TD colSpan=2>
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">165.8</P></SPAN></TD>
<TD width="19%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">18.7</P></SPAN></TD>
<TD vAlign=top width="22%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">32.4</P></SPAN></TD></TR>
<TR>
<TD colSpan=2>
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">6</P></SPAN></TD>
<TD colSpan=2>
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">158.0</P></SPAN></TD>
<TD width="19%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">18.5</P></SPAN></TD>
<TD vAlign=top width="22%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">25.4</P></SPAN></TD></TR>
<TR>
<TD width="9%" rowSpan=2>
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center>横 向</P></TD>
<TD colSpan=2>
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center>表 面</P></TD>
<TD colSpan=2>
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">159.8</P></SPAN></TD>
<TD width="19%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">18.0</P></SPAN></TD>
<TD vAlign=top width="22%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">35.5</P></SPAN></TD></TR>
<TR>
<TD colSpan=2>
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center>中 心</P></TD>
<TD colSpan=2>
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">164.8</P></SPAN></TD>
<TD width="19%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">17.5</P></SPAN></TD>
<TD vAlign=top width="22%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">25.4</P></SPAN></TD></TR>
<TR>
<TD colSpan=2>
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center>平 均 值</P></TD>
<TD colSpan=2>
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">162.49</P></SPAN></TD>
<TD colSpan=2>
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">18.8</P></SPAN></TD>
<TD width="22%">
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体">32.48</P></SPAN></TD></TR>
<TR height=0>
<TD width="12%"></TD>
<TD width="9%"></TD>
<TD width="19%"></TD>
<TD width=0%></TD>
<TD width="19%"></TD>
<TD width=0%></TD>
<TD width="19%"></TD>
<TD width="22%"></TD></TR></TBODY></TABLE></DIV>
<P class=blk18b align=left> 4 生产应用实例<BR><SPAN class=blk14> 图4为我国某实验室试生产的铝合金扁锭和圆锭，其生产条件如下：</SPAN><BR><SPAN class=blk14> 合金种类：3004, 2024<BR> 尺寸：0.52 m×0.13m；<I>φ</I>0.18m<BR> 金属液柱高度：0.038~0.04m<BR> 铸造速度：0.08 m/min<BR> 电流频率：2.5 kHz<BR> 电流：4200 A<BR> 电压：26 V </SPAN>
<P style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center><IMG height=196 src="http://www.chmcw.com/upload/news/RCL/13220_6duqbnimage046.jpg" width=288 v:shapes="_x0000_i1047"></P>
<P class=style1 style="LAYOUT-GRID-MODE: char; TEXT-ALIGN: center" align=center>图4 电磁铸造铝合金锭</P></DIV>
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