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<p>During the solidification of steel ingots, macrosegregation, formed due to solute partitioning, significantly impairs their subsequent processing performance and service reliability. To investigate the mechanism of vertical electromagnetic stirring (V-EMS) in mitigating ingot segregation, a three-phase solidification model coupled with liquid, columnar crystals, and equiaxed crystals was developed to systematically simulated the solidification behavior and segregation evolution in the late stage of ingot solidification. By applying V-EMS with varying current intensities and directions during this stage, the study focused on analyzing its influence on centerline segregation and A-type segregation. The results indicate that the upward electromagnetic force induces a relatively high flow velocity of the molten steel which effectively promotes the migration of solute-enriched elements from the solidification front toward the top of the ingot. Consequently, centerline segregation and A-type segregation are significantly improved. Under an appropriate stirring intensity (current of 1000 A, frequency of 3 Hz), the maximum centerline positive segregation index decreased from 0.196 to 0.145, showing a clear improvement in centerline segregation. Similarly, the A-type segregation at 0.06 m from the ingot center was also notably mitigated, with its maximum segregation index reduced from 0.104 to 0.076. However, when the current is excessively high (1500 A), the intense scouring action leads to excessive solute enrichment, which instead exacerbates centerline positive segregation. The maximum positive segregation index increased to 0.322, and negative segregation even appeared in the regions originally exhibiting A-type positive segregation. In contrast, when the electromagnetic force is directed downward, the wide-top-narrow-bottom geometry of the unsolidified region leads to a lower molten steel flow velocity under the same electromagnetic parameters. In addition, equiaxed grains are driven to accumulate at the ingot center, which exacerbates central negative segregation. As a result, the overall improvement effect is relatively poor. As the stirring current increased from 100 to 1000 A, no improvement in centerline segregation was observed, and the A-type positive segregation even worsened. The maximum positive segregation index in the primary distribution zone of A-type segregation increased from 0.104 to 0.116. This study elucidates the flow-microstructure coupling mechanism through which vertical electromagnetic stirring influences ingot segregation, providing a theoretical foundation for optimizing electromagnetic stirring processes in industry to enhance the homogeneity of large-scale ingots.</p>

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Influence Mechanism of Vertical Electromagnetic Stirring on Centerline and A-Type Segregation in Ingots Based on a Three-Phase Solidification Model

  • 期刊论文

  • 发表日期：

    2026年5月26日

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  • Shuaikang Xia,
  • Yingli Gao,
  • Yuefeng Qi,
  • Huijie Lin,
  • Pu Wang,
  • Jiaquan Zhang

摘要

During the solidification of steel ingots, macrosegregation, formed due to solute partitioning, significantly impairs their subsequent processing performance and service reliability. To investigate the mechanism of vertical electromagnetic stirring (V-EMS) in mitigating ingot segregation, a three-phase solidification model coupled with liquid, columnar crystals, and equiaxed crystals was developed to systematically simulated the solidification behavior and segregation evolution in the late stage of ingot solidification. By applying V-EMS with varying current intensities and directions during this stage, the study focused on analyzing its influence on centerline segregation and A-type segregation. The results indicate that the upward electromagnetic force induces a relatively high flow velocity of the molten steel which effectively promotes the migration of solute-enriched elements from the solidification front toward the top of the ingot. Consequently, centerline segregation and A-type segregation are significantly improved. Under an appropriate stirring intensity (current of 1000 A, frequency of 3 Hz), the maximum centerline positive segregation index decreased from 0.196 to 0.145, showing a clear improvement in centerline segregation. Similarly, the A-type segregation at 0.06 m from the ingot center was also notably mitigated, with its maximum segregation index reduced from 0.104 to 0.076. However, when the current is excessively high (1500 A), the intense scouring action leads to excessive solute enrichment, which instead exacerbates centerline positive segregation. The maximum positive segregation index increased to 0.322, and negative segregation even appeared in the regions originally exhibiting A-type positive segregation. In contrast, when the electromagnetic force is directed downward, the wide-top-narrow-bottom geometry of the unsolidified region leads to a lower molten steel flow velocity under the same electromagnetic parameters. In addition, equiaxed grains are driven to accumulate at the ingot center, which exacerbates central negative segregation. As a result, the overall improvement effect is relatively poor. As the stirring current increased from 100 to 1000 A, no improvement in centerline segregation was observed, and the A-type positive segregation even worsened. The maximum positive segregation index in the primary distribution zone of A-type segregation increased from 0.104 to 0.116. This study elucidates the flow-microstructure coupling mechanism through which vertical electromagnetic stirring influences ingot segregation, providing a theoretical foundation for optimizing electromagnetic stirring processes in industry to enhance the homogeneity of large-scale ingots.