以冷轧冲压用钢薄板坯为研究对象,观察了低倍组织,用原位分析仪研究了铸坯的宏观偏析、致密度和夹杂物.用扫描电镜分析了夹杂物的形貌和成分。结果表明,铸坯心部有2~3个蚀孔,细密树枝晶占74%,柱状晶凝固末端向上倾斜10~20°。碳、硫、铝元素最大偏析度大于3,偏析位置并非分析面的中心对称点。碳、硫元素在厚度中心处有较严重的岛状偏析,铝为多点状偏析,硫、铝元素偏析重合处为CaS-MnS-Al2O3复合夹杂物,其余元素偏析不明显。横截面板厚中心疏松存在硫和铝的富集。
Macrostructure, macrosegregation, density and inclusion of thin slab for cold-rolled steel have been in- vestigated by acid etching and OPA (original position statistic distribution analysis). The micrographs and compo- sition of inclusions have been analyzed by SEM (scanning electron microscope) with EDS (energy dispersive X-ray spectrometer) system. It was found that 2--3 corrosion pits were found in the center of thin slab (equiaxial crystal zone) and fine dendrite made up 74% volume, terminal of column dendrite tilted up at an angle of 10--20° due to upflow of liquid phase. Maximum segregation degree of C, S, Al was more than 3 and location of segregation was not in the center of the analyzed surface. Serious island-like segregation of C, S was detected in the middle of thickness and numerous scattered spotty segregation of AI was also found. The segregation of S and AI was ob- served in the same area; moreover, it was considered as complex inclusions of CaS-MnS-Al2O3 No obvious segre- gation except for C, S, AI was found. Enrichment of S and Al was detected at porosities of central thickness.