Methods of refining and deoxidation of molten steel and methods of steel material production

Abstract

The invention proposes a technique that improves the recovery efficiency of added AI without increasing the cost of vacuum refining. The invention also proposes a method for producing steel materials that have minimal variations in the AI ​​content. In the method of refining and deoxidizing hot-rolled steel using vacuum refining equipment, an AI-containing substance is added to the molten steel inside the vacuum vessel, and the refining and deoxidizing process of hot-rolled steel is carried out in such a way that the temperature changes ΔT] and AI2 of the hot-rolled steel during the AI ​​deoxidation process meet formula (I). It is better that the AI ​​content in the added AI-containing vessel is from 30 to 80% by weight. The method of refining molten steel by deoxidation is a deoxidation step that can produce steel material in which the concentration of Al in steel after the deoxidation step is 0.02% by weight or less. ΔT] I ΔTa < 0 -(1), where ΔT] represents the increase in temperature due to the heat of the Al oxidation reaction, and ΔT1 represents the decrease in temperature due to the heat of the added Al-containing substance.