METHOD FOR REFINING MOLTEN STEEL BY VACUUM DEGASSING

摘要

PURPOSE:To minimize the amt. of deoxidation products in a smelting stage by quantifying the amt. of primary deoxidation products floated in molten steel and the amt. of secondary oxidation products produced and setting the time required to agitate and shake the molten steel after charging a deoxidizer. CONSTITUTION:When clean steel is manufactured, the amts. of nitrogen and silicon in molten steel and the amt. of oxides in slag are measured and the amt. of primary deoxidation products floated and the amt. of secondary oxidation products produced are quantified. The amt. of inclusions in the molten steel is calculated by an equation (the amt. of inclusions)=(the amt. of residue of primary deoxidation products after floating)+(the amt. of secondary oxidation products) and this calculated value is compared to the permitted upper limit. The time required to agitate and shake the molten steel after charging a deoxidizer is set according to the difference and the molten steel is refined. The amt. of inclusions produced from deoxidation products is reduced and clean steel is obtd.