steel manufacturing method
A manufacturing method and technology of molten steel, which is applied in the field of high-clean steel manufacturing, can solve the problems of reduced cleanliness, insufficient gas blowing speed, and inability to mix slag evenly, and achieve the effect of stable control
Active Publication Date: 2014-10-01
JFE STEEL CORP
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Problems solved by technology
However, when the molten steel is not deoxidized, when the slag is stirred by bubbling gas into the molten steel as is usually done, in order to approach the equilibrium relationship with the oxygen concentration in the molten steel, the low-level oxidation of FeO, MnO, etc. in the slag Therefore, there is a problem that the deoxidized molten steel is re-oxidized due to slag, thereby reducing the cleanliness
In addition, the surfacing area of the gas blown into the molten steel is local, so there is a problem that if the gas blowing rate is insufficient, the slag cannot be uniformly stirred, and the reduction of lower oxides or the slag remains. Inadequately cured areas
Method used
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[0064] The present invention will be described in more detail based on examples. The molten steel melted in a top-blown bottom-blown converter with a furnace capacity of 300 tons is refined in an RH vacuum degasser, and then cast in a twin-strand billet continuous caster for casting a billet with a thickness of 235 mm and a width of 1100 mm. The present invention is applied to the process of manufacturing a billet for thin steel plates. In addition, as a comparison, operations outside the scope of the present invention were also performed. Melting was carried out under the same conditions using four furnaces as a unit, and the full continuous casting of the above-mentioned four furnaces was carried out in the continuous casting, and tests were performed using the four furnaces as a unit.
[0065] The produced cast sheet is hot-rolled without surface modification to form a thin steel sheet, the obtained thin steel sheet is pickled, then cold-rolled, and the cold-rolled steel s...
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PURPOSE: A manufacturing method of steel is provided to reduce the amount of slag which flows from a ladle into a tundish by the solidification which follows an ascending melting point of slag by adding an MgO source that contains hydroxide and carbon oxides. CONSTITUTION: A manufacturing method of steel comprises the following steps. Molten steel which is obtained by decarbonizing and refining pig iron is tapped out of a fore hearth into a ladle in a pre-deoxidation stage. A low grade of oxide in the slag is deoxidized; and a density of MgO is simultaneously controlled to be 6-15 mass % by adding metallic Al or Al dross, and by then adding an MgO source to the slag which exists on the molten steel after being tapped. Carbon and dissolved oxygen in the molten steel are reacted with each other under reduced pressure in a degassing device so that a density of the dissolved oxygen is reduced by 0.050wt% or less. A continuous casting machine casts the molten steel into a slab.
Description
technical field [0001] The present invention relates to a method for producing high-clean steel with less oxide-based non-metallic inclusions. Background technique [0002] In the case of Al-killed steel, metal Al is added as a deoxidizer when tapping the steel from the converter or after tapping to remove the oxygen in the molten steel that has increased due to oxidation refining (decarburization refining) in the converter, and then, by continuous casting Machine casting into cast slabs as raw material for rolling. By adding this metal Al, Al is produced as a deoxidized product in molten steel. 2 o 3 , the Al 2 o 3 Al 2 o 3 cracks and surface defects. [0003] Therefore, in order to reduce the remaining Al in the steel 2 o 3 In the past, the following method was adopted: adding metal Al or Al dross to the ladle containing the molten steel after tapping, and reducing the low-level oxides (easily-reductive oxide) (FeO, MnO) of the molten slag existing on the hot stee...
Claims
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IPC IPC(8): C21C7/06C21C7/10
CPCB22D11/108C21C7/00C21C7/04C21C7/06C21C7/10
Inventor 冈本真吾井上畅荒牧则亲锦织正规
Owner JFE STEEL CORP