超低碳铝脱氧钢连铸过程钢中非金属夹杂物的演变

炼钢 ›› 2020, Vol. 36 ›› Issue (6): 39-45.

超低碳铝脱氧钢连铸过程钢中非金属夹杂物的演变

黄日康1，张立峰2，姜仁波3，郭银涛3，杨文1，段豪剑1，姜东滨1，张献光1

(1. 北京科技大学冶金与生态工程学院，北京 100083；
2.燕山大学亚稳材料制备技术与科学国家重点实验室，河北秦皇岛 066044；
3.唐山不锈钢有限责任公司，河北唐山 063105)

出版日期:2020-12-05 发布日期:2020-12-04

Evolution of inclusions in ultra-low carbon Al-killed steel during continuous casting

Online:2020-12-05 Published:2020-12-04

摘要/Abstract

摘要： 对超低碳铝脱氧IF钢连铸过程中间包钢液和连铸坯中的非金属夹杂物进行了扫描电子显微镜能量色散光谱仪分析，并结合相关的热力学计算，分析连铸过程钢中夹杂物演变及其原因。连铸过程钢中夹杂物的成分主要是钛和铝的化合物，平均占比为98 %。中间包钢液中夹杂物以Al₂O₃和Al₂O₃-TiO_x为主，连铸坯中夹杂物以Al₂O₃、Al₂O₃-TiN和TiN为主。在连铸过程中，由于在浸入式水口上结瘤和被结晶器保护渣吸收，钢液中Al₂O₃和Al₂O₃-TiO_x显著减少。随着温度降低，在固液两相区和固相区会析出大量TiN，最终TiN成为连铸坯中主要的夹杂物。采用热力学软件计算了钢冷却和凝固过程中夹杂物的转变，并与检测的结果相对比。结合Scheil方程的计算结果表明，凝固固相分数大于0.58时，凝固前沿固相中有TiN析出；凝固固相分数大于0.83时，凝固前沿钢液中开始析出TiN。连铸坯中夹杂物以TiN为主，占比为86 %，而以Al₂O₃为核心析出的TiN较少，占比为8 %。

关键词: 超低碳铝脱氧钢, 非金属夹杂物, 连铸, 演变

Abstract: In the current study, inclusions in the molten steel and the continuous casting slab of a ultra-low carbon Al-killed steel were analyzed using automatic scanning electron microscopy-energy dispersive spectrometer. The evolution of inclusions in the steel during continuous casting were analyzed and discussed by combining with thermodynamic calculation. The composition of each inclusion in the steel during continuous casting was mainly compounds of titanium and aluminum, with an average content of 98 %. Inclusions of the molten steel in the continuous casting tundish were mainly Al₂O₃and Al₂O₃-TiO_x, and those in the continuous casting slab were mainly Al₂O₃, Al₂O₃-TiN and TiN. Inclusions of Al₂O₃ and Al₂O₃-TiO_x in the molten steel were significantly removed by attaching to the submerged entry nozzle and by removing to mold slag during continuous casting. As the temperature decreased, many TiN particles precipitated in the solid and mushy zone of the steel and became the dominant ones in the slab. A thermodynamic software was used to calculate the transformation of inclusions during cooling and solidification of the steel, showing a result agreeing with the measurement. According to the calculation results of Scheil equation, when the solid fraction was greater than 0.58, TiN can precipitate in the solid steel around the solidification front; when the solid fraction was greater than 0.83, TiN can precipitate in the molten steel around the solidification front. In the continuous casting slab, TiN inclusions accounted for 86 % of the total inclusions, and the TiN inclusions with Al₂O₃ cores accounted for 8 %.

Key words: ultra-low carbon Al-killed steel, non-metallic inclusions, continuous casting, evolution

黄日康, 张立峰, 姜仁波, 郭银涛, 杨文, 段豪剑, 姜东滨, 张献光. 超低碳铝脱氧钢连铸过程钢中非金属夹杂物的演变[J]. 炼钢, 2020, 36(6): 39-45.

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