Blocking material and method for manufacturing alloy steel

Abstract

Provided is a blocking material and a method for manufacturing alloy steel using the same. In maintaining a molten ferro alloy, used when manufacturing a manganese-containing alloy steel, at a temperature of at least a melting point of the ferro alloy, a blocking material layer is formed on the melt surface of the molten ferro alloy by using a blocking material which includes, with respect to the total of 100 wt %, 37-66 wt % of CaO and SiO2, 8-15 wt % of Al2O3, 6-18 wt % of MgO, and 20-30 wt % of MnO, wherein the ratio of CaO to SiO2 (CaO/SiO2) is in a range of 0.95-1.2. Thus, nitrogen in the air may be prevented from being mixed into the molten ferro alloy.

What is claimed is: 
     
         1 . A blocking material, which is added to a melt surface of a manganese-containing molten ferro alloy and covers the melt surface of the molten ferro alloy, comprising, with respect to the total of 100 wt %,
 37-66 wt % of CaO and SiO 2 , 8-15 wt % of Al 2 O 3 , 6-18 wt % of MgO, and 20-30 wt % of MnO, wherein   CaO and SiO 2  are included so that the ratio of CaO to SiO 2  (CaO/SiO 2 ) is in a range of 0.95-1.2.   
     
     
         2 . A method for manufacturing alloy steel, the method comprising:
 preparing a molten ferro alloy; preparing a blocking material;   adding the blocking material into the molten ferro alloy and forming a blocking material layer on a melt surface of the molten ferro alloy;   maintaining the molten ferro alloy at a temperature of at least the melting point of the ferro alloy; and   mixing the molten ferro alloy and the molten steel to manufacture alloy steel.   
     
     
         3 . The method of  claim 2 , wherein the preparing of the molten ferro alloy comprises:
 melting a ferro alloy in a melting furnace to manufacture the molten ferro alloy; and   pouring the molten ferro alloy into a temperature holding furnace.   
     
     
         4 . The method of  claim 2 , wherein the preparing of the molten ferro alloy comprises:
 charging a molten steel into a temperature holding furnace; and   adding at least any one of a ferro alloy or a molten ferro alloy into the temperature holding furnace.   
     
     
         5 . The method of  claim 2 , wherein in the preparing of a blocking material, the blocking material is prepared which includes, with respect to a total of 100 wt %,
 37-66 wt % of CaO and SiO 2 , 8-15 wt % of Al 2 O 3 , 6-18 wt % of MgO, and 20-30 wt % of MnO, wherein   the ratio of CaO to SiO 2  (CaO/SiO 2 ) is in a range of 0.95-1.2.   
     
     
         6 . The method of  claim 5 , wherein the blocking material is added in any one state of a solid phase or a liquid phase. 
     
     
         7 . The method of  claim 6 , wherein the maintaining the molten ferro alloy at a temperature of at least a melting point of the ferro alloy is performed in a range of 1,450-1,550° C. 
     
     
         8 . The method of  claim 7 , wherein in the forming of a blocking material layer on a melt surface of the molten ferro alloy,
 the blocking material layer is formed on an entirety of the melt surface of the molten ferro alloy so that nitrogen in the air is prevented from being mixed into the molten ferro alloy due to contact between the molten ferro alloy and the air.