What are the measures to improve the purity of continuous casting steel

 Purity refers to the quantity, shape and distribution of non-metallic inclusions in steel. The inclusion in steel shall be reduced to the required level according to the steel grade and product quality,

We should start from the following five aspects:

① Reduce [O] content in steel as much as possible.  

② Prevent the molten steel from interacting with air.

③ Reduce the interaction between molten steel and refractory materials.  

④ Reduce slag entrainment in molten steel.  

⑤ The improved flow promotes the floating of inclusions in molten steel.

In terms of process operation, the following measures shall be taken:

(1) Slag free tapping: slag retaining balls are adopted for the converter and eccentric bottom tapping is adopted for the electric furnace to prevent a large amount of slag from falling into the ladle.  

(2) Ladle refining: select the appropriate refining method according to the steel grade, to uniform the temperature, fine tune the composition, reduce the oxygen content, remove gas inclusions, etc.  

(3) Non oxidation casting: after the molten steel is treated by ladle, the total oxygen content in the steel can be reduced from 130ppm to below 20ppm. If the injection flow from ladle to tundish is not protected or poorly protected, the total oxygen content in tundish steel will rise to the range of 60-100ppm, which will return to the level before external refining, and the effect of external refining will be wasted.  

(4) Tundish metallurgy: the tundish adopts large capacity, and the addition of retaining walls and dams is an effective measure to promote the floating of inclusions. For example, for 6T tundish, the scrap rate of slab inclusion is 12%, and the inclusion is 0.82 pieces / m2; 12t tundish + retaining wall, 0 scrap inclusion in slab, 0.04 inclusions / m2.

(5) Submerged nozzle + casting mold powder: the mold powder shall be able to fully absorb inclusions. The submerged entry nozzle material, nozzle shape and insertion depth shall be favorable for the floating and separation of inclusions.

We Changxing Refractory Material Co.,LTD is professional manufacturer and supplier of refractory materials for more than 30 years. Our high quality casting powder are good sold to many countries say South Africa, Bangladesh, Indonesia, Malaysia, etc.  

Article Source:  improve the purity of continuous casting steel
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