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通过对比试验确定了采用“BOF→LF→RH→CC”流程生产高强钢WYS700,该工艺流程合金收得率和成分命中率高,过程增氮少,成品氮含量低。为保证浇钢顺利进行,对钢水进行轻钙处理,硅钙线用量0.88 kg/t,轻钙处理工艺后,连浇炉数由4炉提高至7炉。通过扫描电镜观察,中间包钢中非金属夹杂物基本呈球形,分布比较分散,夹杂物的尺寸基本小于5μm,达到了夹杂物变性的目的,改善了钢水可浇性。通过控制钢水成分与温度、优化结晶器倒锥度、调整比水量、优化保护渣与结晶器流场等,高强钢漏钢率由1.90%降低到0.35%,铸坯裂纹改判率由5.5%降低到0.45%。
Through the comparison test, the production process of high-strength steel WYS700 using “BOF → LF → RH → CC” process was confirmed. The yield of the alloy and the hit rate of the composition were high, the process increased the amount of nitrogen and the finished product had low nitrogen content. In order to ensure the smooth pouring of steel, the molten calcium was treated with 0.88 kg / t of calcium silicate. After light calcium treatment, the number of pouring furnaces was increased from 4 to 7. The scanning electron microscopy showed that the non-metallic inclusions in the tundish were basically spherical, with relatively dispersed distribution. The size of inclusions was basically less than 5μm, which achieved the purpose of inclusions denaturation and improved the pourability of molten steel. By controlling the composition and temperature of the molten steel, optimizing the mold taper, adjusting the specific water, optimizing the mold flux and mold flow field, the rate of steel breakout in high strength steel decreased from 1.90% to 0.35%, and the rate of slab cracking reduced from 5.5% 0.45%.