Grain-oriented electrical steel sheet and method for manufacturing same

Abstract

The present invention relates to a grain-oriented electrical steel sheet and a method for manufacturing the same. The grain-oriented electrical steel sheet contains 2.0 wt % or more to 5.0 wt % or less of Si, 0.005 wt % or more to 0.04 wt % or less of acid-soluble Al, 0.01 wt % or more to 0.2 wt % or less of Mn, 0.01 wt % or less (excluding 0 wt %) of N, 0.01 wt % or less (excluding 0 wt %) of S, 0.01 wt % or more to 0.05 wt % or less of Sb, 0.02 wt % or more to 0.08 wt % or less of C, 0.0005 wt % or more to 0.045 wt % or less of P, 0.03 wt % or more to less than 0.08 wt % of Sn, and 0.01 wt % or more to 0.2 wt % or less of Cr, and contains balance Fe and other inevitable impurities.

1 . A grain-oriented electrical steel sheet containing 2.0 wt % or more to 5.0 wt % or less of Si, 0.005 wt % or more to 0.04 wt % or less of acid-soluble Al, 0.01 wt % or more to 0.2 wt % or less of Mn, 0.01 wt % or less (excluding 0 wt %) of N, 0.01 wt % or less (excluding 0 wt %) of S, 0.01 wt % or more to 0.05 wt % or less of Sb, 0.02 wt % or more to 0.08 wt % or less of C, 0.0005 wt % or more to 0.045 wt % or less of P, 0.03 wt % or more to less than 0.08 wt % of Sn, and 0.01 wt % or more to 0.2 wt % or less of Cr, and containing balance Fe and other inevitable impurities. 
     
     
         2 . The grain-oriented electrical steel sheet of  claim 1 , wherein:
 the grain-oriented electrical steel sheet satisfies the following Equation 1 calculated by contents (wt %) of the respective components:
   −0.32Mn+0.012Si+0.016≤C≤−0.014Mn+0.02Si.  [Equation 1]
 
   
     
     
         3 . The grain-oriented electrical steel sheet of  claim 1 , wherein:
 the grain-oriented electrical steel sheet satisfies the following Equation 2 calculated by contents (wt %) of the respective components:
   Sn+Sb≤5Cr.  [Equation 2]
 
   
     
     
         4 . The grain-oriented electrical steel sheet of  claim 1 , wherein:
 the grain-oriented electrical steel sheet satisfies the following Equation 1 and the following Equation 2 calculated by contents (wt %) of the respective components:
   −0.32Mn+0.012Si+0.016≤C≤−0.014Mn+0.02Si, and  [  1]
 
   Sn+Sb≤5Cr.  [  2]
 
   
     
     
         5 . The grain-oriented electrical steel sheet of  claim 4 , wherein:
 a fracture of an austenite phase in the grain-oriented electrical steel is 20 to 30%.   
     
     
         6 . The grain-oriented electrical steel sheet of  claim 5 , wherein:
 an area of crystal grains of which a ratio between the longest diameters and the shortest diameters is 1.0 or more among crystal grains of which lengths of the shortest diameters are 3 mm or more is 5% or more of an area of all the crystal grains.   
     
     
         7 . A method for manufacturing a grain-oriented electrical steel sheet, comprising:
 reheating a steel slab containing 2.0 wt % or more to 5.0 wt % or less of Si, 0.005 wt % or more to 0.04 wt % or less of acid-soluble Al, 0.01 wt % or more to 0.2 wt % or less of Mn, 0.01 wt % or less (excluding 0 wt %) of N, 0.01 wt % or less (excluding 0 wt %) of S, 0.01 wt % or more to 0.05 wt % or less of Sb, 0.02 wt % or more to 0.08 wt % or less of C, 0.0005 wt % or more to 0.045 wt % or less of P, 0.03 wt % or more to less than 0.08 wt % of Sn, and 0.01 wt % or more to 0.2 wt % or less of Cr, and including balance Fe and other inevitable impurities;   manufacturing a steel sheet by performing hot rolling, hot-rolled sheet annealing, and cold rolling on the reheated steel slab;   performing decarbonization annealing and nitriding annealing on the cold-rolled steel sheet; and   finally annealing the decarbonization annealed and nitriding annealed steel sheet.   
     
     
         8 . The method for manufacturing a grain-oriented electrical steel sheet of  claim 7 , wherein:
 the steel slab satisfies the following Equation 1 calculated by contents (wt %) of the respective components:
   −0.32Mn+0.012Si+0.016≤C≤−0.014Mn+0.02Si.  [Equation 1]
 
   
     
     
         9 . The method for manufacturing a grain-oriented electrical steel sheet of  claim 7 , wherein:
 the steel slab satisfies the following Equation 2 calculated by contents (wt %) of the respective components:
   Sn+Sb≤5Cr.  [Equation 2]
 
   
     
     
         10 . The method for manufacturing a grain-oriented electrical steel sheet of  claim 7 , wherein:
 the steel slab satisfies the following Equation 1 and the following Equation 2 calculated by contents (wt %) of the respective components:
   −0.32Mn+0.012Si+0.016≤C≤−0.014Mn+0.02Si, and  [Equation 1]
 
   Sn+Sb≤5Cr.  [Equation 2]
 
   
     
     
         11 . The method for manufacturing a grain-oriented electrical steel sheet of  claim 10 , wherein:
 in the reheating of the steel slab, a temperature is 1000 to 1250° C.   
     
     
         12 . The method for manufacturing a grain-oriented electrical steel sheet of  claim 11 , wherein:
 in the manufacturing of the steel sheet by performing the hot rolling, the hot-rolled sheet annealing, and the cold rolling on the reheated steel slab,   a hot-rolled sheet annealing temperature is 900 to 1200° C.   
     
     
         13 . The method for manufacturing a grain-oriented electrical steel sheet of  claim 12 , wherein:
 in the manufacturing of the steel sheet by performing the hot rolling, the hot-rolled sheet annealing, and the cold rolling on the reheated steel slab,   a cold rolling thickness is 0.10 mm or more to 0.50 mm or less.   
     
     
         14 . The method for manufacturing a grain-oriented electrical steel sheet of  claim 13 , wherein:
 in the manufacturing of the steel sheet by performing the hot rolling, the hot-rolled sheet annealing, and the cold rolling on the reheated steel slab,   the cold rolling is performed as once cold rolling of which a cold rolling ratio is 87% or more.   
     
     
         15 . The method for manufacturing a grain-oriented electrical steel sheet of  claim 14 , wherein:
 in the performing of the decarbonization annealing and the nitriding annealing on the cold-rolled steel sheet,   the decarbonization annealing and the nitriding annealing are simultaneously performed, the nitriding annealing is independently performed after the decarbonization annealing, or the decarbonization annealing is independently performed after the nitriding annealing.   
     
     
         16 . The method for manufacturing a grain-oriented electrical steel sheet of  claim 15 , wherein:
 in the performing of the decarbonization annealing and the nitriding annealing on the cold-rolled steel sheet,   the decarbonization annealing and the nitriding annealing are simultaneously performed, and an annealing temperature is 800 to 950° C.   
     
     
         17 . The method for manufacturing a grain-oriented electrical steel sheet of  claim 16 , further comprising:
 before the final annealing of the decarbonization annealed and nitriding annealed steel sheet,   applying an annealing separating agent to the decarbonization annealed and nitriding annealed steel sheet.   
     
     
         18 . The method for manufacturing a grain-oriented electrical steel sheet of  claim 17 , wherein:
 in the final annealing of the decarbonization annealed and nitriding annealed steel sheet,   a final annealing temperature is 800 to 1250° C.   
     
     
         19 . The method for manufacturing a grain-oriented electrical steel sheet of  claim 18 , wherein:
 the final annealing of the decarbonization annealed and nitriding annealed steel sheet   is performed under an atmosphere including one or more of nitrogen and hydrogen, and   is performed under a 100% hydrogen atmosphere after a temperature arrives at the final annealing temperature.