酒钢CSP流程SPCC钢夹杂形成机理

对酒钢CSP流程SPCC两个浇次在LF进站、LF中期、LF出站、中包、铸坯和轧制过程分别取钢样，用SEM-EDS分析其夹杂物及成分. 结果表明，在喂铝线后，钢液中很快形成大量形状不规则Al2O3夹杂物，随着精炼进行夹杂物存在两种变性路线：Al2O3-MgO·Al2O3-CaAlMg复合夹杂物和Al2O3-CA6-CA2-CA-低熔点夹杂物. 经过钙处理后大部分夹杂物可较好地变性到低熔点液相区或固液两相共存区. 夹杂物变性越好，则钢液中夹杂物球形化率越高，总量也越小，夹杂物成分对其尺寸也有重要影响. 分析了外层被钙铝酸盐和CaS包裹的双层夹杂物的形成机理，前者由于钢中Ca还原MgO·Al2O3尖晶石中Mg或Al2O3中Al；后者由于在铸坯凝固过程中温度降低及元素S的偏析，造成液芯中S浓度升高，其与Ca在已有的固体夹杂物核心的表面析出CaS. 在轧制过程中，前者变形能力较好，后者的外层CaS易与内部核心分离，甚至产生微裂纹.

Formation Mechanism of Inclusions in SPCC during CSP Process in JISCO

Steel samples were taken out at the start, intermediate and end of LF refining in the tundish from casting slabs and rolling strips for Steel Plate Cold Commercial (SPCC) during compact strip production (CSP) process in JISCO. SEM-EDS was used to analyze the morphology and composition of inclusions. The results showed that a large number of Al2O3 inclusions with irregular morphology after Al feeding formed, and two routes were found for Al2O3 inclusion modification for SPCC, Al2O3-MgO·Al2O3-CaAlMg multi-component and Al2O3-CA6-CA2-CA-liquid inclusions, and the majority of inclusions could be modified into liquid or solid-liquid coexisting region after calcium treatment. Furthermore, the better the modification of inclusion, the higher the spherical rate and the lower the amount of remaining inclusion in liquid steel. The inclusion composition also significantly affected its size, but the size was determined by other factors. Finally, the formation mechanisms of multi-component inclusions surrounded with calcium-aluminate or CaS ring were analyzed. The former was due to the reduction of Mg in MgO·Al2O3 spinel by Ca or reduction of Al in Al2O3, and the latter was because CaS precipitated directly surrounding solid inclusion core during solidification due to the segregation of S and temperature decreasing. During rolling process, the former had better formative performance, while the outer CaS layer of the latter was easily separated from the inner core and even micro-cracks were caused.