Grain oriented electrical steel sheet

Abstract

An electrical steel sheet contains, as components, by mass %, 0.005% or less of C, 1.0% to 8.0% of Si, and 0.005% to 1.0% of Mn; one or more selected from Nb, Ta, V, and Zr such that a total content thereof is 10 to 50 ppm; and the balance being Fe and unavoidable impurities, wherein at least 10% of the content of Nb, Ta, V, and Zr is in the form of precipitates; the precipitates have an average diameter (equivalent circle diameter) of 0.02 to 3 μm; and secondary recrystallized grains of the steel sheet have an average grain size of 5 mm or more.

1 . A grain oriented electrical steel sheet comprising, by mass %, 0.005% or less of C, 1.0% to 8.0% of Si, and 0.005% to 1.0% of Mn; one or more selected from the group consisting of Nb, Ta, V, and Zr such that a total content thereof is 10 to 50 ppm; and the balance being Fe and unavoidable impurities, wherein at least 10% of the content of Nb, Ta, V, and Zr is in the form of precipitates; the precipitates having an average diameter (equivalent circle diameter) of 0.02 to 3 μm; and secondary recrystallized grains of the steel sheet have an average grain size of 5 mm or more. 
     
     
         2 . The grain oriented electrical steel sheet according to  claim 1 , further comprising at least one selected from the group consisting of, by mass %, 0.010% to 1.50% of Ni, 0.01% to 0.50% of Cr, 0.01% to 0.50% of Cu, 0.005% to 0.50% of P, 0.005% to 0.50% of Sn, 0.005% to 0.50% of Sb, 0.005% to 0.50% of Bi, and 0.005% to 0.100% of Mo. 
     
     
         3 . The grain oriented electrical steel sheet according to  claim 1 , wherein a groove is formed in a surface of the steel sheet, the groove having a shape of a solid line or broken lines, a width of 50 to 1,000 μm, and a depth of 10 to 50 μm, and extending at an angle of 15° or less with respect to a direction perpendicular to a rolling direction of the steel sheet. 
     
     
         4 . A method for producing an iron core, comprising shearing the grain oriented electrical steel sheet according to  claim 1  to provide sheets and subsequently stacking the sheets without subjecting the sheets to stress relief annealing. 
     
     
         5 . The grain oriented electrical steel sheet according to  claim 2 , wherein a groove is formed in a surface of the steel sheet, the groove having a shape of a solid line or broken lines, a width of 50 to 1,000 μm, and a depth of 10 to 50 μm, and extending at an angle of 15° or less with respect to a direction perpendicular to a rolling direction of the steel sheet. 
     
     
         6 . A method for producing an iron core, comprising shearing the grain oriented electrical steel sheet according to  claim 2  to provide sheets and subsequently stacking the sheets without subjecting the sheets to stress relief annealing. 
     
     
         7 . A method for producing an iron core, comprising shearing the grain oriented electrical steel sheet according to  claim 3  to provide sheets and subsequently stacking the sheets without subjecting the sheets to stress relief annealing. 
     
     
         8 . A method for producing an iron core, comprising shearing the grain oriented electrical steel sheet according to  claim 5  to provide sheets and subsequently stacking the sheets without subjecting the sheets to stress relief annealing.