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<p>To solve the frequent submerged entry nozzle (SEN) clogging problem caused by high-melting-point inclusions such as Al<sub>2</sub>O<sub>3</sub> and MgO·Al<sub>2</sub>O<sub>3</sub> in Al-deoxidized steels, low-carbon SPHC (steel plate hot rolling commercial) steel was taken as an example to study the popular calcium treatment process by a novel thermodynamic calculation method together with industrial trials. A reasonable calcium treatment process parameter was proposed based on the ratio of total calcium content to total oxygen content (T.Ca/T.O) with much improved inclusions modification effect and steel castability. Based on thermodynamic calculations using the composition of a representative heat, it was found that the required T.Ca content range to produce inclusions in a low-melting-point liquid state at 1600 °C was 0.00162 to 0.00358 wt pct. However, the detected T.Ca in the heat was only 0.0007 wt pct, which resulted in the formation of high-melting-point solid inclusions such as CaO·2MgO·8Al<sub>2</sub>O<sub>3</sub>, CaO·2Al<sub>2</sub>O<sub>3</sub> and spinel, further causing observed SEN clogging. To address this issue, a Ca–Al–O ternary phase diagram was constructed, and the correlation between the T.Ca/T.O and inclusion types was clearly revealed. It is shown that when the T.Ca/T.O is controlled between 0.57 and 0.74, the inclusions in the steel are in a liquid state. According to the calculation, the calcium wire feeding amount was adjusted, and the T.Ca/T.O in the representative heat increased significantly from 0.19 to 0.63. As a result, the average inclusion composition in steel shifted from 12&#xa0;pct CaO–4&#xa0;pct MgO–84&#xa0;pct Al<sub>2</sub>O<sub>3</sub> to 31&#xa0;pct CaO–3&#xa0;pct MgO–66&#xa0;pct Al<sub>2</sub>O<sub>3</sub>, indicating an increase in liquid inclusions and a reduction in SEN clogging tendency.</p>

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A Total Calcium to Total Oxygen Mass Ratio Control Model Based on Ca–Al–O Ternary Phase Diagram and Its Application to Calcium Treatment Process of Al-Deoxidized Steels

  • 期刊论文

  • 发表日期：

    2026年7月27日

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  • Yuhang Wang,
  • Haiyan Tang,
  • Kaimin Wang,
  • Qiuyue Xiang,
  • Xingyu Jia,
  • Jiaquan Zhang

摘要

To solve the frequent submerged entry nozzle (SEN) clogging problem caused by high-melting-point inclusions such as Al2O3 and MgO·Al2O3 in Al-deoxidized steels, low-carbon SPHC (steel plate hot rolling commercial) steel was taken as an example to study the popular calcium treatment process by a novel thermodynamic calculation method together with industrial trials. A reasonable calcium treatment process parameter was proposed based on the ratio of total calcium content to total oxygen content (T.Ca/T.O) with much improved inclusions modification effect and steel castability. Based on thermodynamic calculations using the composition of a representative heat, it was found that the required T.Ca content range to produce inclusions in a low-melting-point liquid state at 1600 °C was 0.00162 to 0.00358 wt pct. However, the detected T.Ca in the heat was only 0.0007 wt pct, which resulted in the formation of high-melting-point solid inclusions such as CaO·2MgO·8Al2O3, CaO·2Al2O3 and spinel, further causing observed SEN clogging. To address this issue, a Ca–Al–O ternary phase diagram was constructed, and the correlation between the T.Ca/T.O and inclusion types was clearly revealed. It is shown that when the T.Ca/T.O is controlled between 0.57 and 0.74, the inclusions in the steel are in a liquid state. According to the calculation, the calcium wire feeding amount was adjusted, and the T.Ca/T.O in the representative heat increased significantly from 0.19 to 0.63. As a result, the average inclusion composition in steel shifted from 12 pct CaO–4 pct MgO–84 pct Al2O3 to 31 pct CaO–3 pct MgO–66 pct Al2O3, indicating an increase in liquid inclusions and a reduction in SEN clogging tendency.