铝镇静冷镦钢CaS结瘤机理及改进

 对铝镇静冷镦钢在浇铸过程中出现的浸入式水口结瘤问题进行了系统研究,结瘤物中主要为C12A7(12CaO·7Al₂O₃)、CaS以及少量的MgO、TFe等,CaS所占比例达到36.91%,CaS含量过高,是造成水口结瘤的主要原因。结合生产过程分析发现,当钙处理时钢水中硫含量偏高,或喂入钙含量过多时,则生成大量的CaS夹杂,促使水口结瘤。通过改进脱氧造渣工艺、优化钙处理工艺等一系列措施,将钙处理前钢水中硫质量分数控制在0.005 0%以下,钙处理后钢水中钙质量分数控制在0.001 4%～0.002 6%,使钢水中Al₂O₃夹杂改性充分,同时避免生成CaS夹杂造成水口结瘤,有效解决了CaS夹杂引起的水口结瘤问题,提高了铝镇静冷镦钢钢水浇注性能,使连浇炉数由最低的10炉/中间包提高至16炉/中间包以上。

Improvement on mechanism of nozzle clogging caused by CaS inclusions in Al-killed cold heading steel

Through the research of nozzle clogging in the casting process of Al-killed cold heading steel, the nodules are C12A7, CaS, a little mount of MgO and TFe, etc, and the main reason for the nozzle clogging is the inclusions with a high percentage of CaS which is up to 36.91%. Combined with the production process, it is found that a large number of CaS inclusions will be formed when the w(S]) or the calcium content in molten steel is too high. Through a series of measures, such as improving deoxidization and slagging process, optimizing calcium treatment process, etc, w(S]) in the molten steel before calcium treatment is controlled below 0.005 0%, and the w(Ca]) after calcium treatment is controlled within 0.001 4%-0.002 6%, the result is that the modification of Al₂O₃ inclusions in molten steel is sufficient, and the formation of CaS inclusions causing nozzle clogging is avoided. The problem of nozzle clogging caused by CaS inclusions is effectively solved, and the castability of molten steel of aluminum killed cold heading steel is improved, the number of continuous casting heats is increased from 10 to 16 on average.