超低碳钢连铸板坯近表面非金属夹杂物分布

Near-Surface Distribution of No-Metallic Inclusion in Continuous Casting Slab of Ultra-Low-Carbon Steel

摘要: 本文针对1350 mm × 230 mm断面超低碳钢板坯连铸过程，通过连铸坯取样与定量金相分析，考察了恒拉速和变拉速条件下板坯近表面非金属夹杂物的分布情况。结果表明，小于10 μm夹杂物在各厚度层分布较为均匀，大于10 μm夹杂物主要分布在铸坯距表面0~5 mm厚度范围内。当拉速约为1.2 m∙min⁻¹时，有利于控制卷渣和夹杂物聚集的发生，近表面夹杂物密度较低；拉速过低(0.8 m∙min⁻¹)或过高(1.4 m∙min⁻¹)以及拉速变化过程均可导致铸坯近表面夹杂物数密度显著升高，需采取技术措施以控制结晶器钢液流场稳定。

Abstract: In this paper, focusing on the slab continuous casting process of ultra-low-carbon steel with 1350 mm × 230 mm cross section, via sampling and quantitative metallography analysis, the effect of continuous casting speed and its variation during operation on the distribution of no-metallic in-clusion near the slab surface were verified. Results show that, the inclusions with particle size less than 10 μm distribute in the slab sub-surface uniformly from 0 mm to 9 mm, but those with particle size larger than 10 μm mainly distribute within 5 mm. When the continuous casting speed is 1.2 m•min⁻¹, the inclusion number density in the slab sub-surface is low for the reason of inhibiting mold flux entrapment and inclusion aggregation. Under the condition of lower continuous casting speed e.g. 0.8 m•min⁻¹, higher continuous casting speed e.g. 1.4 m•min⁻¹, and decreasing of continuous casting speed, the inclusion number density increases significantly, so suitable tech-nologies should be applied to control the stabilization of fluid flow in the mold.