| 摘要 |
<p>PURPOSE:To perfectly prevent the MnS deposition on the bottom side of a continuously cast slab and obtain a ingot of excellent cleanliness by adding Ca under prescribed addition conditions while measuring the amount of dissolved O2 of the molten steel to be poured into the intermediate vessel between a ladle and a mold. CONSTITUTION:The molten steel which has beforehand been treated and controlled to T[O]<=0.003%, [S]<=0.002% is poured into the intermediate vessel provided at the intermediate from a ladle up to a mold. The amount of the dissolved O2 in the molten steel poured into the intermediate vessel is continuously or intermittently measured by an ordinary electrochemical measuring method. Thence, Ca or Ca alloy is added continuously or intermittently to the molten steel in this intermediate vessel under the addition conditions determined by the equation based on the results of said measurement. As a result, MnS does not deposit at all in the axial center part on the bottom side of a continuous slab, and harmful acids and sulfide such as Ca type cluster inclusions are extremely few, thus the ingot of excellent cleanliness is obtained.</p> |
