| 摘要 |
PURPOSE:To produce ultra clean steel having super low sulfur content, super low hydrogen content and incorporated Ca by a single process by the following method in which when molten steel is refined under reduced pressure, only inert gas is blown into the molten steel after a desulfurizer has been injected, and then Ca is blown into the molten metal after the inside pressure of said tank has been restored to atomospheric pressure. CONSTITUTION:When molten steel is refined under reduced pressure in a ladle combined with a vacuum degassing tank, first, the pressure in the vacuum tank is reduced and desulfurizer is blown into the molten steel with the carrier gas such as inert gas under reduced pressure, thereby carrying out desulfurization, deoxidation and dehydrogenation. After the addition of the desulfurizer has been stopped, only the carrier gas is injected and accordingly the hydrogen is removed. Next, the inside pressure of the vacuum degassing tank is restored to atomospheric pressure, and Ca-component is added to the molten steel by injecting a Ca-alloy or a Ca-compound. By this process, ultra clean steel having a super low sulfur content, super low oxygen content, super low hydrogen content and incorporated Ca may be produced in high yield and in stable condition. |
