Abstract：In view of the problems such as too thin slag layer, frequent bond alarm and too many longitudinal cracks on the surface of slab during high speed continuous casting of low carbon steel thin slab, the optimization direction of the lubrication and heat transfer performance of the mold flux is determined based on the fully consideration of the solidification shrinkage characteristics of low carbon steel, and industrial experiments are carried out. The basicity of the mold flux is increased from 1.10 to 1.30, the mass fraction of Li2O is increased from 0.57% to 1.06%, the mass fraction of Na2O is increased from 5.48% to 8.16%, and the mass fraction of Carbon is reduced from 7.71% to 6.72%. The rheological properties of two kinds of mold flux and the three-layer structure of slag film are further studied. It is found that after optimization, the proportion of liquid slag layer in the slag film increases, and the lubrication coefficient(α) of the slag film increases; at the same time, the proportion of crystal layer in the slag film also increases to a certain extent, and the heat transfer coefficient(β) of the slag film increases, so that the lubrication performance and the control heat transfer capacity of the mold flux are improved. From the results of mineral phase analysis, it can be seen that the increase of basicity of the mold flux will promote the precipitation of wollastonite to a certain extent, leading to the increase of crystallization rate and thermal resistance of slag film, thus controlling the heat transfer. The production practice shows that after the increase of casting speed, the use of the new type of mold flux can basically avoid the generation of bond and crack, and the production efficiency and slab quality are significantly improved. It has a certain guiding significance for the production and application of the low carbon steel thin slab high speed mold flux in the enterprise in the future.
2020, Vol. 55 
