低硫钢种的低硅精炼技术

Low silicon control for steel grades with low sulphur mass percent

讨论了冶炼低硅低硫钢种（w（[S]）≤0.003 0%和w（[Si]）≤0.05%）的难点,着重从热力学角度分析了在脱硫的同时防止增硅的方法,阐述了防止增硅的具体应对措施。利用Factsage软件计算熔渣组成的活度和熔化特性,利用最大平衡铝质量分数的概念指出最佳的精炼熔渣组分控制为w（（MgO））=5%-8%、w（（CaO＋MgO））=62%-66%、w（（SiO2））=4%-6%、w（（Al2O3））=29%-33%。若钢-渣间反应达到平衡,硅质量分数极为容易超标,因此控制钢-渣之间反应不平衡是控制增硅的关键,钢-渣间增硅反应不平衡度应控制在-6.0--4.0。措施实施后,LF炉精炼结束硅质量分数均值由0.034 5%降低至0.022 2%,统计不合格率由10.3%降至0,过程能力指数Cpk值为1.35,达到受控状态,预测长期不合格率仅为0.2%。极大提升了低硫低硅产品生产的稳定性,取得了良好的效益。

The way to control the silicon content when w（[S]）≤0.003 0% and w（[Si]）≤0.05% was introduced. Factsage was used to calculate the activities and other melting characteristics of melted slags,following with maxium aluminium content in metal,which showed the optimized slag composition are,w（（MgO））= 5%-8%,w（（CaO＋MgO））= 62%-66%,w（（SiO2））= 4%-6%,w（（Al2O3））= 29%-33%. It was revealed that the silicon content will exceed the upper limit when slag-metal reactions go balanced. So the imbalance degree of slag-metal reactions plays the biggest role in controlling silicon pickup,which should range between-6.0 and-4.0. Some actions were signed and applied,consequence in average silicon content decreasing from 0.034 5% to 0.022 2%,unqualified rate decreasing from 10.3% to 0,process capability index 1.35,and the predicted unqualified ratio 0.2%. This dramatically improved the stability of the production process of low silicon and sulphur grades.