The baking temperature of the tundish not only affects the performance of refractory materials and the temperature control of molten steel, but also has a profound impact on the stability of the continuous casting process and the quality of the ingot. From the smooth progress of the pouring process to the guarantee of the intrinsic quality of the ingot, the baking temperature plays a vital role.
The appropriate baking temperature is the key prerequisite for the successful pouring of the tundish.
During the pouring, if the baking temperature of the tundish is insufficient and the wall temperature is low, the molten steel will solidify rapidly near the wall after being poured in, which may cause nozzle blockage or poor steel flow. Studies have shown that when the baking temperature of the tundish is as low as 900℃, the incidence of nozzle nodules during the pouring process can reach 30%, while when the temperature is increased to above 1100℃, the incidence of nodules can be reduced to less than 5%. When a steel plant produces aluminum-containing steel, it increases the success rate of pouring from the original 66.6% to 84.06% by increasing the baking temperature of the tundish to 1150℃, which significantly improves the smoothness of production.
The baking temperature has an important influence on the corrosion resistance and life of the refractory materials of the tundish.
Higher baking temperature can fully sinter the refractory material to form a dense structure, thereby improving its ability to resist erosion by molten steel and slag. Experimental data show that when the baking temperature rises from 900℃ to 1100℃, the erosion resistance index of magnesium dry material to slag increases from 1.8 to 2.5, and the erosion resistance increases by about 39%. After a steel plant increased the baking temperature of the tundish, the number of continuous casting furnaces of the tundish was extended from about 10 to more than 15, and the refractory consumption cost was reduced by about 20%.
The baking temperature of the tundish will also affect the intrinsic quality of the ingot.
The appropriate baking temperature can reduce the temperature drop of the molten steel in the tundish, so that the molten steel maintains good fluidity, which is conducive to the floating removal of inclusions. Studies have shown that when the baking temperature of the tundish is appropriate, the removal rate of inclusions larger than 50μm in the molten steel can reach more than 80%, while the removal rate is only about 60% when the temperature is insufficient. In addition, a stable molten steel temperature can also help control the solidification structure of the ingot and reduce defects such as central porosity and segregation. A steel plant optimized the tundish baking process, reducing the center porosity level of the ingot from 2.0 to 1.0 and the center segregation index from 1.2 to 1.05, significantly improving the quality of the ingot.
