(1. 大連理工大學 材料科學與工程學院，大連 116024；
2. 寶山鋼鐵股份有限公司，上海 201900)
摘 要: 測試分析新型電磁攪拌器內(nèi)螺旋磁場和旋轉(zhuǎn)磁場的磁感應強度、分布和作用規(guī)律，研究螺旋磁場對Pb-80%Sn過共晶合金凝固組織影響的作用機理，并與無磁場和旋轉(zhuǎn)磁場條件下合金凝固組織的形貌特征及成分分布進行對比分析。結(jié)果表明：螺旋磁場相比于旋轉(zhuǎn)磁場可以在鑄錠內(nèi)部更大區(qū)域內(nèi)形成均勻攪拌，更易于破碎和細化枝晶組織，既能促進橢球或球狀晶的生成，又能更好地改善宏觀偏析；在頻率一定的情況下，初生相晶粒尺寸隨著勵磁電流的增大而減小；當勵磁電流為125 A時，旋轉(zhuǎn)磁場和螺旋磁場細化晶粒的效果最好；繼續(xù)增大電流，晶粒產(chǎn)生粗化；螺旋磁場可基本消除成分偏析，并在較小勵磁電流(100 A)下達到采用旋轉(zhuǎn)磁場(125 A)時的最佳攪拌效果。
關(guān)鍵字: Pb-80%Sn過共晶合金；成分偏析；螺旋磁場；旋轉(zhuǎn)磁場
HOU Xiao-guang2, XING Qing-yuan1, ZHANG Xing-g
（1. School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024, China;
2. Baoshan Iron and Steel Company Limited, Shanghai 201900, China）
Abstract:A new type of electromagnetic stirrer was measured to investigate the spiral and rotating magnetic field with their distributions of magnetic induction and mechanism of action, and the effect of spiral magnetic field on solidification structure of Pb-80%Sn hypereutectic alloy was also studied, with comparison of alloys solidified and component distribution in the conventional condition and rotating magnetic field. The results show that, compared with rotating magnetic field, the spiral magnetic field can lead to a more uniform stirring in a larger zone of the ingot, which is more beneficial to breaking and refining the dendrites structure, thus promoting the formation of ellipsoidal or equiaxed grains and reducing macrosegregation. At a fixed frequency, the grains sizes of the primary phase increase with the excitation current and, an optimal effect can be achieved when the current reaches 125 A for both spiral and rotating magnetic field, while higher excitation current will lead to the growth of grains. The macrosegregation can be substantially eliminated by spiral magnetic field and a lower current (100 A) is effective to obtain the same optimal stirring effect (125 A) of rotating magnetic field.
Key words: Pb-80%Sn hypereutectic alloy; composition segregation; spiral magnetic field; rotating magnetic field
