METHOD OF PRODUCING EXTRA LOW CARBON STEEL HAVING PHOSPHORUS, NITROGEN AND TITANIUM

摘要

PURPOSE: A method of producing extra low carbon steels having phosphorus, nitrogen and titanium is provided to prevent plug and shrinkage of submerged entry nozzle, thus minimize fluctuation of molten steel in mold. CONSTITUTION: The method comprises the steps of tapping refined molten steel in such a manner that the thickness of slag is less than 150mm; adjusting oxygen content in the molten steel to 200-400 ppm by aluminum input; injecting nitrogen gas into oxygen-controlled molten steel; injecting argon gas into the molten steel after titanium pouring into the molten steel; and continuous casting the refined molten steel by mathematical formula shown below at temperature ranges higher than theoretical solidification temperature by 20-30°C. Theoretical solidification temperature=1536°C-{78 x £C|%+4.9x£Mn|%+7.6x£Si|%+34.4x£P|%+38x£S|%+4.7x£Cu|%+3.1x£Ni|%+1.3x£Cr|%+3. 6x£S.Al|%}.