IF钢连铸头坯洁净度研究

Study on Cleanliness of IF Steel First Slab

应用氧氮成分分析、大样电解分析、扫描电镜分析、能谱分析等分析手段，研究了转炉-RH-连铸生产IF钢头坯洁净度的变化规律，并与正常坯洁净度水平进行对比分析。结果表明：沿拉坯方向头坯T[O]和[N]含量呈明显下降趋势。头坯大型夹杂物含量都明显高于正常坯，并沿拉坯方向总体呈减少趋势，4．4rn后大型夹杂物含量接近正常坯水平。铸坯中的大型夹杂物在厚度方向分布不均匀，内弧含量要明显高于外弧含量。头坯中大型夹杂物主要是尺寸为140～300μm和大于300／zm两类，分别占总夹杂物质量分数的22．6％和56．8％，此类夹杂物主要来源于结晶器卷渣、中间包卷渣、二次氧化产物以及钢包引流砂。

The cleanliness of IF steel first slab produced by BOF-RH-CC and the difference with the cleanliness of normal slab were studied by means of total oxygen and nitrogen content analysis,SLIME,SEM,EDS,etc.It is found that the T[O] and [N] of first slab are obviously decreasing along casting direction.The large-sized inclusions contents of first slab are obviously higher than those of normal slab,and generally decrease along casting direction,and are close to those of normal slab after the position of 4.4 m along first slab.The distribution of large-sized inclusions is non-homogeneous along thickness direction of slab,which contents of inner arc slab are obviously higher than those of outer arc slab.The size of large-sized inclusions are mainly from 140 to 300 μm and the size over 300 μm,which accounts individually for 22.6% and 56.8% of total large-sized inclusions and are from slag entrapment in mould or tundish,reoxidation products and stuffing sand.