低碳钢亚快速凝固过程夹杂物的生成规律

Inclusion Formation Law in the Process of Sub-rapid Solidification of Low Carbon Steel

薄带钢中夹杂物是影响其表面质量和材料性能的重要因素。采用真空感应熔炼和铜模吸铸的方法制取了Si-Mn脱氧后加Ti脱氧的低碳钢薄带,薄带中全氧含量为79μg/g,凝固冷速范围为240~960 K/s。利用此工艺制备的薄带中大多数夹杂物尺寸小于1μm,最大夹杂直径为8.5μm。其中尺寸在0.2~0.5μm夹杂物的数量密度为825个/mm2,其在截面上的分布规律为:表面数量最多,达1 570个/mm2,中心和1/4处数量接近。尺寸在0.5~5μm夹杂物的数量密度为510个/mm2,各厚度位置分布均匀。尺寸大于5μm夹杂物的数量密度为15个/mm2,各厚度位置分布均匀。对夹杂物的成分、形貌和结构分析显示,每个夹杂均由多个晶体组成,整体形貌近似球形,为TinO2n-1+Mn S复合夹杂,其中以钛氧化物为主体,Mn S附着在钛氧化物的表面区域。

Inclusion in thin strip steel is an important factor affecting its surface quality and properties. The low carbon steel strip was produced by vacuum induction melting and copper mold casting through Si-Mn deoxidation and then Ti deoxidation. The total oxygen content in the strip was79 μg/g,and the solidification rate was in range of 240 K/s to 960 K/s. The results showed that the inclusions in the strip were submicron-sized and diameter of the maximum one was 8. 5 μm. The number density of inclusions in the range of 0. 2 μm to 0. 5 μm was 825 per square milimeter,and the one distributed in surface was 1 570 per square milimeter,which was more than those distributed in the center and in a quarter thickness from surface. The number density of inclusions in the range of0. 5 μm to 5 μm was 510 per square milimeter and evenly distributed in different sites. The number density of inclusions with diameter larger than 5 μm was 15 per square milimeter,which also evenly distributed in different sites. The composition,morphology and structure of the inclusions were analyzed,it was showed that the inclusions were multi-crystals with near spherical morphology,belonging to TinO2 n-1+ Mn S composite inclusions,titanium oxide was the main component and Mn S was attached to the surface area of titanium oxide.