Method of continuous casting of steel

Abstract

A subject for the invention is to provide a method of continuous steel casting in which although an “immersion nozzle constituted of a refractory material comprising alumina as the main component” is used for continuous steel casting, this nozzle suffers little fusion loss and no alumina deposition thereon and a clean steel casting can be stably obtained. The method of continuous steel casting of the invention uses a combination of a mold powder having a fluorine content lower than 3% by weight and a viscosity at 1,300° C. of from 4 P to 10,000 P and an immersion nozzle constituted of a refractory material comprising alumina as the main component (e.g., an alumina refractory and/or an alumina-carbon refractory).

1 . A method of continuous steel casting which comprises continuously casting a steel while feeding a molten steel into a casting mold through an immersion nozzle and supplying a mold powder into the casting mold, 
 wherein a combination of a mold powder having a fluorine content lower than 3% by weight and a viscosity at 1,300° C. of from 4 P to 100,000 P and an immersion nozzle comprising a refractory material comprising alumina as a main component is used.    
     
     
         2 . The method of continuous steel casting of  claim 1 , wherein the mold powder has a rupture strength at 1,300° C. of 3.7 g/cm 2  or higher.  
     
     
         3 . The method of continuous steel casting of  claim 1  or  2 , wherein the mold powder has a chemical composition comprising from 5 to 25% by weight of Al 2 O 3 , from 25 to 70% by weight of SiO 2 , from 10 to 50% by weight of CaO, up to 20% by weight of MgO, and from 0 to 2% by weight of F (unavoidable impurity).  
     
     
         4 . The method of continuous steel casting of  claim 1 , wherein the refractory material comprises an alumina refractory and/or an alumina-carbon refractory.  
     
     
         5 . The method of continuous steel casting of  claim 4 , wherein the alumina refractory and/or alumina-carbon refractory contains one or more members selected from silica (SiO 2 ), silicon carbide (SiC), boron carbide (B 4 C), silicon nitride (Si 3 N 4 ), aluminum nitride (AlN), zirconium boride (ZrB 2 ), magnesium boride (Mg 3 B 2 ), zirconium sulfate (ZrSO 4 ), silicon (Si), and aluminum (Al).  
     
     
         6 . The method of continuous steel casting of any one of  claims 1  to  5 , wherein as the molten steel, aluminum-killed steel, silicon-killed steel, high-oxygen steel, stainless steel, steel for electromagnetic steel sheets, calcium-treated steel, high-manganese steel, free-cutting steel, boron steel, steel cord, case hardening steel, or high-titanium steel is used.