Grain-oriented electrical steel sheet and method for manufacturing the same

Abstract

A grain oriented electrical steel sheet according to one embodiment of the present disclosure comprises: 1.0 wt % to 4.0 wt % of Si, 0.002 wt % or less (excluding 0%) of C and 0.001 wt % to 0.1 wt % of Bi, with the remainder being Fe and other unavoidable impurities.

1 . A grain oriented electrical steel sheet comprising: 1.0 wt % to 4.0 wt % of Si, 0.002 wt % or less (excluding 0%) of C and 0.001 wt % to 0.1 wt % of Bi, with the remainder being Fe and other unavoidable impurities. 
     
     
         2 . The grain oriented electrical steel sheet of  claim 1 ,
 further including 0.05 wt % or less (excluding 0%) of Mn, 0.01 wt % or less (excluding 0%) of Al, 0.001 wt % or less (excluding 0%) of S and 0.001 wt % or less (excluding 0%) of N.   
     
     
         3 . The grain oriented electrical steel sheet of  claim 1 ,
 further including 0.1 wt % or less (excluding 0%) of P, 0.05 wt % or less (excluding 0%) of Mo, 0.1 wt % or less (excluding 0%) of Sn and 0.05 wt % or less (excluding 0%) of Sb.   
     
     
         4 . The grain oriented electrical steel sheet of  claim 1 , wherein:
 the volume ratio of the crystal grains having a diameter of 20 μm to 500 μm is 80% or more.   
     
     
         5 . The grain oriented electrical steel sheet of  claim 1 , wherein:
 the volume ratio of the Goss crystal grains parallel in the error range of 15° or less with respect to the sheet surface of the steel sheet is 80% or more.   
     
     
         6 . A method of manufacturing a grain oriented electrical steel sheet, the method comprising: heating a slab comprising 1.0 to 4.0 wt % of Si, 0.01 wt % to 0.4 wt % of C, with the remainder being Fe and other unavoidable impurities;
 hot-rolling the slab to produce a hot-rolled sheet;   hot-rolled sheet-annealing the hot-rolled sheet;   cold-rolling the hot-rolled sheet-annealed hot-rolled sheet to produce a cold-rolled sheet;   decarburization-annealing the cold-rolled sheet; and   final-annealing the decarburization-annealed electrical steel sheet,   wherein after the annealing of the hot-rolled sheet, the average diameter of the crystal grain in the surface layer of the hot-rolled sheet is 150 μm to 250 μm.   
     
     
         7 . The method of  claim 6 , wherein
 the slab further includes 0.001 wt % to 0.1 wt % of Bi.   
     
     
         8 . The method of  claim 6 , wherein
 the slab further includes 0.05 wt % or less (excluding 0%) of Mn, 0.01 wt % or less (excluding 0%) of Al, 0.001 wt % or less (excluding 0%) of S and 0.001 wt % or less (excluding 0%) of N.   
     
     
         9 . The method of  claim 6 , wherein:
 the slab further includes 0.1 wt % or less (excluding 0%) of P, 0.05 wt % or less (excluding 0%) of Mo, 0.1 wt % or less (excluding 0%) of Sn and 0.05 wt % or less (excluding 0%) of Sb.   
     
     
         10 . The method of  claim 6 , wherein:
 the heating temperature in the heating of the slab is 1100 to 1350° C.   
     
     
         11 . The method of  claim 6 , wherein:
 the hot-rolled sheet-annealing includes the decarburization process.   
     
     
         12 . The method of  claim 6 , wherein:
 the hot-rolled sheet-annealing includes a first hot-rolled sheet-annealing at a temperature of 850 to 1000° C. and a dew-point temperature of 50 to 70° C. and a second hot-rolled sheet-annealing at a temperature of 1000 to 1200° C. and a dew-point temperature of 0° C. or less.   
     
     
         13 . The method of  claim 12 , wherein:
 the first hot-rolled sheet-annealing is performed for 10 to 300 seconds, and the second hot-rolled sheet-annealing is performed for 10 to 180 seconds.   
     
     
         14 . The method of  claim 6 , wherein:
 the process from the cold-rolling to the final-annealing is continuously performed.   
     
     
         15 . The method of  claim 6 , wherein:
 the process of the cold-rolling and the decarburization-annealing is repeated at least twice.   
     
     
         16 . The method of  claim 6 , wherein:
 the decarburization-annealing is performed at a temperature of 850 to 1000° C. and a dew-point temperature of 50 to 70° C.   
     
     
         17 . The method of  claim 12 , wherein:
 the final-annealing includes a first final-annealing at a temperature of 850 to 1000° C. and a dew-point temperature of 70° C. or less and a second final-annealing at a temperature of 1000 to 1200° C. under an atmosphere of H 2  50 volume % or more.   
     
     
         18 . The method of  claim 17 , wherein:
 the first final-annealing is performed for 10 to 180 seconds and the second final-annealing is performed for 10 to 600 seconds.