Oriented electrical steel sheet and manufacturing method thereof

Abstract

A method for manufacturing an oriented electrical steel sheet according to an exemplary embodiment of the present invention includes: providing a slab including, as wt %, Si at equal to or less than 4.0% (excluding 0%), C at 0.001% to 0.4%, and Mn at 0.001% to 2.0%, and including a balance including Fe and inevitably mixed and input impurities; reheating the slab; manufacturing a hot steel sheet by hot-rolling the slab; performing hot-rolled steel sheet annealing to the hot steel sheet; primarily cold-rolling the hot-rolled steel sheet annealed hot steel sheet; decarburization-annealing the cold-rolled steel sheet; secondarily cold-rolling the decarburization-annealed steel sheet; and finally annealing the cold-rolled steel sheet, wherein, regarding the finally annealed steel sheet, a size 2L of a magnetic domain existing in a grain is less than a thickness D of the steel sheet (2L<D).

What is claimed is: 
     
         1 . A method for manufacturing an oriented electrical steel sheet, comprising:
 providing a slab including, as wt %, Si at equal to or less than 4.0% (excluding 0%), C at 0.001% to 0.4%, and Mn at 0.001 to 2.0%, and including a balance including Fe and inevitably mixed and input impurities;   reheating the slab;   manufacturing a hot steel sheet by hot-rolling the slab;   performing hot-rolled steel sheet annealing to the hot steel sheet;   primarily cold-rolling the hot-rolled steel sheet annealed hot steel sheet;   decarburization-annealing the cold-rolled steel sheet;   secondarily cold-rolling the decarburization-annealed steel sheet; and   finally annealing the cold-rolled steel sheet,   wherein, regarding the finally annealed steel sheet, a size 2L of a magnetic domain existing in a grain is less than a thickness D of the steel sheet.   
     
     
         2 . The method of  claim 1 , wherein
 the slab includes Si at equal to or less than 1 wt % (excluding 0 wt %).   
     
     
         3 . The method of  claim 1 , wherein
 the slab further includes Al at equal to or less than 0.01 wt % (excluding 0 wt %).   
     
     
         4 . The method of  claim 1 , wherein
 a reheating temperature of the slab is 1050° C. to 1350° C.   
     
     
         5 . The method of  claim 1 , wherein
 reduction rates in the primarily cold-rolling and the secondarily cold-rolling are respectively 50% to 70%.   
     
     
         6 . The method of  claim 1 , wherein
 the decarburization-annealing of the cold-rolled steel sheet and the secondarily cold-rolling of the decarburization-annealed steel sheet are repeated at least twice.   
     
     
         7 . The method of  claim 1 , wherein
 the decarburization-annealing is performed in an atmosphere including hydrogen with a dew point temperature of 0° C. at a temperature of 800° C. to 1150° C.   
     
     
         8 . The method of  claim 1 , wherein
 the finally annealing includes a first step for performing the same in an atmosphere with the dew point temperature of 10° C. to 70° C. at the temperature of 850° C. to 1150° C., and a second step for performing the same in a mixed gas atmosphere including hydrogen and nitrogen with a dew point temperature that is equal to or less than 10° C. at a temperature of 900° C. to 1200° C.   
     
     
         9 . The method of  claim 8 , wherein
 the first step is performed for equal to or less than 300 seconds, and the second step is performed for 60 seconds to 300 seconds.   
     
     
         10 . The method of  claim 1 , wherein
 the finally annealing is continuously performed after the cold-rolling.   
     
     
         11 . The method of  claim 1 , wherein
 an amount of carbon in the electrical steel sheet is equal to or less than 0.003 wt % (excluding 0 wt %) after the finally annealing.   
     
     
         12 . The method of  claim 1 , wherein
 regarding the finally annealed steel sheet, a volumetric fraction of a grain with an orientation that is within 15 degrees from an orientation {110}<001> is equal to or greater than 50%.   
     
     
         13 . The method of  claim 1 , wherein
 regarding the finally annealed steel sheet, a volumetric fraction of a grain with a particle diameter of 20 μm to 1000 μm is equal to or greater than 50%.   
     
     
         14 . An oriented electrical steel sheet comprising, as wt %, Si at equal to or less than 4.0% (excluding 0%), C at equal to or less than 0.003% (excluding 0%), and Mn at 0.001 to 2.0%, and a balance including Fe and an impurity that is inevitably mixed and input,
 wherein a size 2L of a magnetic domain existing in a grain is less than a thickness (D) of a steel sheet.   
     
     
         15 . The oriented electrical steel sheet of  claim 14 , wherein
 Si is included to be equal to or less than 1.0 wt % (excluding 0 wt %).   
     
     
         16 . The oriented electrical steel sheet of  claim 14 , wherein
 Al is further included to be equal to or less than 0.01 wt % (excluding 0 wt %).   
     
     
         17 . The oriented electrical steel sheet of  claim 14 , wherein
 a size 2L of a magnetic domain existing in a grain is 10 to 500 μm.   
     
     
         18 . The oriented electrical steel sheet of  claim 14 , wherein
 a volumetric fraction of a grain with an orientation that is within 15 degrees from an orientation {110}<001> is equal to or greater than 50%.   
     
     
         19 . The oriented electrical steel sheet of  claim 14 , wherein
 a volumetric fraction of a grain with a particle diameter of 20 μm to 1000 μm is equal to or greater than 50%.