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针对某钢厂结晶器液面翻腾导致卷渣严重与中间包过热度控制缺乏依据为背景,对结晶器内流态和过热度对表面质量影响开展研究。文献调研与大量线状缺陷电镜分析发现,导致线状缺陷的夹杂物主要是氧化铝和保护渣,且引起线状缺陷的大尺寸夹杂物主要分布在铸坯表层5mm内。减少吹氩量与增大浸入深度可提高双股流比例,基于水模型和工业试验,提出控制临界吹气量得到双股流。应用该结果后,消除了结晶器液面翻腾现象,提高中间包过热度可减少钩状坯壳深度与铸坯表层夹杂物数量。综合考虑钢水洁净度提出冷轧薄板钢过热度控制在25~40℃。基于以上措施,该厂炼钢缺陷导致降级率由1.1%降至0.6%。
Aiming at the serious problem of slag entrapment and superheat control of tundish in the mold of a steel mill, the influence of flow and superheat on the surface quality in the mold was studied. Literature research and a large number of linear defects electron microscopy analysis found that the main cause of linear defects inclusions are alumina and mold flux, and cause linear defects of large size inclusions are mainly distributed in the slab surface within 5mm. Reducing the argon blowing capacity and increasing the immersion depth can increase the ratio of double-flow. Based on the water model and industrial tests, it is proposed to control the critical blowing capacity to obtain double-flow. The application of this result eliminates the mold surface turbulence and increases the superheat of the tundish to reduce the depth of the hooked shell and the amount of inclusions in the surface of the slab. Considering the cleanliness of molten steel, it is proposed that the degree of superheat of the cold rolled sheet steel should be controlled at 25-40 ℃. Based on the above measures, the factory steel defects led to a downgrade from 1.1% to 0.6%.