包晶钢板坯纵裂纹分析及保护渣优化

doi:10.13228/j.boyuan.issn1005-4006.20200147

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Abstract In the production of Q235B、Q345B peritectic steel slabs, a variety of surface longitudinal cracks defects were found. According to the analysis of macroscopic morphology, metallurgical structure and microscopic morphology, it is confirmed that the surface longitudinal cracks are formed in the mold, the basic reason is the uneven growth of the composite shell in the mold caused by the volume shrinkage during the transformation from δ to γ phase, and the mold flux is the key factor. In order to reduce the heat transfer from the slab to the mold, the existing mold flux was optimized. The basicity of mold flux was increased from 1.39 to 1.53, and the crystallization property of mold flux was improved to enhance the slow cooling of molten steel at meniscus. At the same time, the melting temperature is reduced from 1 171 to 1 130 ℃, and the viscosity is kept at 0.08 Pa·s at 1 300 ℃, this can ensure the consumption of mold flux to ensure the lubrication of the billet. The production practice shows that the surface quality of the slab is improved obviously by using the optimized mold flux, and the proportion of longitudinal cracks is reduced from 10.58% to 1.85%.

Key words： peritectic steel slab surface longitudinal crack mold flux basicity

Received: 26 December 2020

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	LI Yu-di
	ZHANG Fa-bin

Cite this article:

LI Yu-di,ZHANG Fa-bin. Analysis of longitudinal cracks and optimization of mold flux for peritectic steel slab[J]. CONTINUOUS CASTING, 2021, 40(2): 57-60.

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http://www.chinamet.cn/Jweb_lz/EN/10.13228/j.boyuan.issn1005-4006.20200147 OR http://www.chinamet.cn/Jweb_lz/EN/Y2021/V40/I2/57

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