| 摘要 |
<p>PROBLEM TO BE SOLVED: To restrain manganese loss when a high manganese steel is melted, by top-blowing oxygen onto molten steel in a vacuum-degassing vessel from a top-blown lance to perform a vacuum-decarburization. SOLUTION: When the high manganese steel is melted by blowing the oxygen onto the molten steel 2 in the vacuum-degassing vessel 3 from the top-blown lance 4 to perform the vacuum-decarburization, while adjusting the vacuum degree in the vacuum-degassing vessel 3 to 2500-14000 Pa, CaCO3 is discharged from a hopper 8 and supplied into the oxygen gas flowing into the top-blown lance 4 through a supplying tube 9 and the molten steel 2 is cooled by blowing the powdery CaCO3 near a firing point colliding the oxygen gas against the molten steel 2. Vaporized loss of the manganese in the molten steel is drastically restricted in comparison with the conventional method, and the improvements of the Mn yield and the hitting ratios of the carbon concentration and the manganese concentration targeted in the molten steel can be obtained.</p> |
