Method for manufacturing ferritic stainless steel slabs with equiaxed grain structures and the ferritic stainless steel manufactured by it
a technology of equiaxed grain structure and ferritic stainless steel, which is applied in the direction of furnaces, electric furnaces, furnace types, etc., can solve the problems of large interface energy, difficult inclusions to serve as non-uniform nucleating sites of ferrite, and inability to obtain equiaxed grain structures easily, etc., to achieve the effect of generating available tin
a technology of equiaxed grain structure and ferritic stainless steel, which is applied in the direction of furnaces, electric furnaces, furnace types, etc., can solve the problems of large interface energy, difficult inclusions to serve as non-uniform nucleating sites of ferrite, and inability to obtain equiaxed grain structures easily, etc., to achieve the effect of generating available tin
US20090223603A1Inactive Publication Date: 2009-09-10POHANG IRON & STEEL CO LTD
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[0068]The example of the present invention will now be described.
[0069]In order to have the composition of Fe-17% Cr, scrap iron and ferroalloy are melted in an electric furnace and then subjected to oxygen decarburization process in an AOD refining furnace to be tapped into a ladle at 1780° C. There are molten steel and slag in the ladle. In other to improve vacuum oxygen decarburization efficiency, the slag is removed in a mechanical manner. At this time, the temperature of the molten steel is about 1600° C. The ladle is moved to the vacuum oxygen decarburization refining stand in which a vacuum cover is put on it and oxygen gas is then supplied to it using a lance on the upper part of the molten steel. With this process, after oxygen decarburization reaction is completed, the temperature of the molten steel is raised up to about 1670° C. and the composition of the molten steel is analyzed as in the following table 2.
TABLE 2ComponentCSiMnSCrTiAlNConcentration0.0050.00.30.008170.00...
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Abstract
Disclosed is a method for manufacturing ferritic stainless steel slabs with equiaxed grain structures and the ferritic stainless steel manufactured by it, which control concentration of alumina inclusions in molten steel to maximize an available TiN generation effect serving as a non-uniform nucleating site of ferrite when solidifying it, thereby improving equiaxed crystal ratio, the method comprising the steps of: performing oxygen decarburization reaction by blowing oxygen from the upper part of the molten steel in a vacuum oxygen decarburization ladle; injecting Al in the molten steel to which the oxygen decarburization reaction is made for Cr2O3 reduction; making composite deoxidation by injecting deoxidizer in the molten steel into which the Al is injected for the Cr2O3 reduction; making alloying process by injecting alloying metal in the molten steel; first judging for judging whether Al concentration is in the range of a setting value by analyzing the Al concentration in the molten steel; if the Al concentration satisfies the setting value, stirring it using inert gas and second judging for judging whether alumina inclusion concentration in the final molten steel corresponds to a target value; and if the alumina inclusion concentration satisfies the target value, continuously casting the molten steel.
Description
BACKGROUND ART[0001]1. Field of the Invention[0002]The present invention relates to a method for manufacturing ferritic stainless steel slabs with equiaxed grain structures and the ferritic stainless steel manufactured by it, and more specifically to a method for manufacturing ferritic stainless steel slabs with equiaxed grain structures and the ferritic stainless steel manufactured by it which control concentration of alumina inclusions in molten steel to maximize an available TiN generation effect serving as a non-uniform nucleating site of ferrite when solidifying it, thereby improving equiaxed crystal ratio.[0003]2. Description of Related Art[0004]In general, there is a case that Ti of 0.2-0.5% is added to a ferritic stainless steel with Cr concentration of 10-30% in order to improve its corrosion-resistance. In this case, TiN is formed by the following equation from a steel making process to a continuous casting process, wherein when its size and distribution are proper, it ser...
Claims
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Patent Timeline
10 Sep 2009
Publication
US20090223603A1
- IPC
- C22C38/00; B22D11/108
- CPC
- C21C7/0006; C21C7/10; C21C7/0685; C21C7/06; C21C5/52; C21C7/00; C21C7/04
- Inventors
- PARK, JOO-HYUN; SONG, HYO-SEOK