(东北大学 材料电磁过程研究教育部重点实验室, 沈阳 110004)
摘 要: 采用低熔点Sn-32%Pb-52%Bi合金模拟钢液，研究交变磁场作用下金属熔池液面的波动和变形行为。结果表明：交变磁场会使金属液面发生弧形变形，液面一直处于波动状态；熔池在三相点附近形成汇聚撞击的两个回流区，导致液面上三相点附近的波动最剧烈，易造成表面卷渣；增加线圈电流强度，液面变形增大，波动加剧；当熔池外壁面的磁感应强度达到约50 mT时，液面的波动幅度达到约±3 mm，应有一个合理的电流强度；适当增加频率可减小电磁力对自由表面波动的影响范围，有利于增大弯月面变形和减小液面波动，频率控制在30 kHz左右较适宜；液面位于线圈中心高度附近时，弯月面变形较大，液面波动较剧烈，初始液面控制在线圈高度中心有利于节能。波动规律可解释电磁软接触连铸中铸坯表面振痕随电流强度大小的变化规律。
关键字: Sn-Pb-Bi合金；模拟钢液；液面变形；液面波动；连铸；交变磁场
alternating magnetic field in mold
（Key Laboratory of Electromagnetic Processing of Materials ,
Ministry of Education, Northeastern University, Shenyang 110004, China）
Abstract:Simulating molten steel using Sn-32%Pb-52%Bi low-melting-point alloy, the metal free surface fluctuation and deformation behavior with alternating magnetic field was investigated. The results show that the meniscus becomes camber due to alternating electromagnetic field, and the free surface is keeping fluctuating. There are two recirculation flow zones near the triple-phase point where the up flow is encountered with the down flow, which enhances the fluctuation of the free surface in the vicinity of triple-phase point and tends to cause slag entrapment. On the whole free surface, the fluctuation in the vicinity of triple-phase point is the most violent. With increasing coil current intensity, the meniscus distortion is enlarged, and the fluctuation of the free surface is aggravated. When the magnetic flux density on the outer surface of the molten bath is about 50 mT, the fluctuation amplitude of free surface is about ±3 mm. The coil current intensity should be controlled in a reasonable range. With increasing frequency, the effect of electromagnetic force on the free surface fluctuation reduces. Within a proper frequency range, with increasing magnetic field frequency, it tends to increase the meniscus height and decrease the fluctuation of free surface. While the initial metal level is located at the center height of the coil, the meniscus deformation is larger and the metal free surface fluctuation is also more violent. In order to save energy, the metal level should be located at the center of the coil height. The fluctuation behavior clearly interprets the change law of billet surface oscillation marks with coil current intensity in the electromagnetic soft-contact continuous casting process.
Key words: Sn-Pb-Bi alloy; simulating molten steel; meniscus deformation; free surface fluctuation; continuous casting process; alternating magnetic field
