| 摘要 |
PURPOSE:To produce a stainless steel of extremely low nitrogen concn. by charging the molten steel refined in a converter as it is into an AOD furnace, and controlling its components by decarbonizing the same then subjecting the molten steel to vacuum degassing after oxygen blowing. CONSTITUTION:In a converter, molten steel is subjected to decarbonization, dephosphorization, desulfurization, etc. by oxygen blowing, and the steel is tapped in an undisoxidized state into a ladle. The molten steel in the ladle is charged into an AOD furnace where gaseous mixture of Ar and O2 are glown to the molten steel, whereby it is decarbonized. When the C attains a prescribed value, the blowing gases are charged over to gaseous Ar alone, thence a reducing agent such as Fe-Si alloy is charged to reduce Cr. Thence, floating slag is removed, after which the gaseous Ar is changed over to gaseous O2 and oxygen blowing is canied out. The m olten steel is then contained in a ladle, and is carried to a DH vacuum degassing plant, where it is vacuum degassed, whereby the level of O is lowered. Thereby, the stainless steel of an extremely low nitrogen level is obtained. |
