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应用PMO改善ø250 mmSWRH82B硬线钢连铸坯质量

Improving quality of ø 250 mm SWRH82B hard-wire steel continuous casting billets by PMO

  • 摘要: SWRH82B高碳钢碳含量较高,在ø250 mm圆坯连铸过程中受选分结晶与溶质富集效应影响显著,易形成严重中心碳偏析和缩孔缺陷,进而在后续拉拔加工中诱发断丝问题。为改善ø250 mm SWRH82B硬线钢连铸坯质量,将脉冲磁致振荡(PMO)凝固均质化技术引入天津荣程钢铁公司连铸生产线,研究了PMO对ø 250 mm连铸SWRH82B钢凝固组织及中心偏析的影响。结果表明,施加PMO后铸坯横截面中心碳偏析指数由1.19 降低至1.09,最大降幅超过43%。铸坯等轴晶区宽度由13.1 cm提高至15.4 cm,等轴晶率由27.4%提升至37.9%,二次枝晶臂间距最大值由185.9 μm降低至159.9 μm,凝固组织显著细化。

     

    Abstract: Due to its high carbon content, SWRH82B high-carbon steel is significantly affected by selective crystallization and solute enrichment effects during the continuous casting of ø250 mm round billets, which easily leads to severe central carbon segregation and shrinkage cavity defects, and further induces wire breakage problems in subsequent drawing processes. To improve the quality of ø250 mm SWRH82B hard wire steel continuous casting billets, Pulsed Magneto-Oscillation (PMO) solidification structure homogenization technology was introduced into the continuous casting production line of Tianjin Rockcheck United Iron and Steel Group Co., Ltd., the effects of PMO on the solidification structure and central segregation of ø250 mm continuously cast SWRH82B steel were studied. The results show that after applying PMO, the central carbon segregation index of the billet cross-section decreased from 1.19 to 1.09, with a maximum reduction of more than 43%. The width of the equiaxed crystal zone of the billet increased from 13.1 cm to 15.4 cm, the equiaxed grain ratio increased from 27.4% to 37.9%, the maximum value of the secondary dendrite arm spacing decreased from 185.9 μm to 159.9 μm, and the solidification structure was significantly refined.

     

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