Production practice of controlling oxygen content of ultra-low carbon steel in billet smelting
To address the issues of poor castability and subsurface bubbles of the billet in the production of ultra-low carbon steel in the billet caster,an analysis was conducted on the water outlet blockage.The findings revealed that the nodulation products were mainly Al2O3.The aforementioned issues often appear when the oxygen content in tundish is low.At the same time,according to the principle of subsurface bubbles in ultra-low carbon steel,CO bubbles will be produced in the solidification of molten steel when the oxygen content in tundish is high.Combined with the production experience,it is concluded that the stable control of oxygen content in tundish is the key to solve these two problems.In this research,the influence of oxidation of molten steel and steel slag during refining and continuous casting on oxygen content in tundish was analyzed.The following control measures were taken:the FeO content of slag was maintained at approximately 10％;the oxygen content at the LF furnace station was controlled between 0.030 0％and 0.045 0％,while the oxygen conten at the RH station was kept between 0.000 8％and 0.001 5％;the duration of station furnace time was reduced and the continuous casting process adopted protective pouring;the oxygen content in the tundish was stabilised between 0.002 5％and 0.004 5％.Through these measures,the number of continuous casting furnaces in single ladle has been increased to 5,and the subsurface bubbles on the slab surface have been effectively controlled.
ultra-low carbon steelbilletsubsurface bubblecastabilitytundish oxygennumber of continuous casters
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