Method of manufacturing a nonoriented electromagnetic steel sheet

Abstract

A method for manufacturing a non-oriented electrical steel sheet including hot-rolling a steel slab containing 0-0.010% of C; at least one of Si and Al in a total amount of 0.03% to 0.5%; 0.5% or less of Mn; 0.10% or more to 0.26% or less of P; 0.015% or less of S; and 0.010% or less of N, on a mass percentage basis, the remainder being Fe and unavailable impurities, under conditions of a heating temperature in a single-phase austenite region and a coiling temperature of 650° C. or less; descaling the hot-rolled sheet to cold-roll the descaled sheet once or twice or more with an intermediate annealing sub-step therebetween; and then finish-annealing the cold-rolled sheet at a temperature of 700° C. or more in the single-phase ferrite region.

1 - 8 . (canceled)  
     
     
         9 . A method for manufacturing a non-oriented electrical steel sheet comprising: 
 hot-rolling a steel slab containing: 
 0-0.010% of C;  
 at least one of Si and Al in a total amount of 0.03% to 0.5%;  
 0.5% or less of Mn;  
 0.10% or more to 0.26% or less of P;  
 0.015% or less of S; and  
 0.010% or less of N, on a mass percentage basis, the remainder being Fe and unavailable impurities,  
   under conditions of a heating temperature in a single-phase austenite region and a coiling temperature of 650° C. or less;    descaling the hot-rolled sheet to cold-roll the descaled sheet once or twice or more with an intermediate annealing sub-step therebetween; and then    finish-annealing the cold-rolled sheet at a temperature of 700° C. or more in the single-phase ferrite region.    
     
     
         10 . A method for manufacturing a non-oriented electrical steel sheet comprising: 
 hot-rolling a steel slab containing: 
 0-0.010% of C;  
 at least one of Si and Al in a total amount of 0.03% to 0.5%;  
 0.5% or less of Mn;  
 0.10% or more to 0.26% or less of P;  
 0.015% or less of S; and  
 0.010% or less of N, on a mass percentage basis,  
 Ni is not contained or the Ni content is 1.0% by mass or less, and  
 the remainder being Fe and unavoidable impurities,  
   under conditions of aheating temperature in a single-phase austenite region and a coiling temperature of 650° C. or less;    annealing the hot-rolled sheet at a temperature of 900° C. or more in a single-phase ferrite region or at a temperature of more than the A c3  transformation point in the single-phase austenite region;    descaling the annealed sheet to cold-roll the descaled sheet once or twice or more with an intermediate annealing sub-step therebetween; and then    finish-annealing the cold-rolled sheet at a temperature of 700° C. or more in the single-phase ferrite region.    
     
     
         11 . A method for manufacturing a non-oriented electrical steel sheet comprising: 
 hot-rolling a steel slab containing: 
 0-0.010% of C;  
 at least one of Si and Al in a total amount of more than 0.5% to 2.5%;  
 0.5% or less of Mn;  
 0.10% or more to 0.26% or less of P;  
 0.015% or less of S:  
 0.010% or less of N; and  
 2.3% or less of Ni according to needs,  
   on a mass percentage basis, the remainder being Fe and unavoidable impurities, and satisfying: 
 at least one of the formula P≦P A  and the formula P F ≦0.26,  
   wherein        P   A =0.2Si+0.12Mn−0.32Al+0.05Ni 2 +0.10Ni+0.36   (1): and    P   F =−0.34Si+0.20Mn−0.54Al+0.24Ni 2 +0.28Ni+0.76   (2),    where the unit of each element content is mass %,    under conditions of a heating temperature of 1000-1200° C. and a coiling temperature of 650° C. or less;    annealing the hot-rolled sheet as needed;    descaling the hot-rolled or annealed sheet to cold-roll the descaled sheet once or twice or more with an intermediate annealing sub-step therebetween; and then    finish-annealing the cold-rolled sheet.    
     
     
         12 . The method for manufacturing a non-oriented electrical steel sheet according to  claim 9 , wherein the steel slab further comprises: 
 at least one of Sb and Sn in a total amount of 0.40% or less on a mass percentage basis.    
     
     
         13 . The method according to  claim 9 , wherein the steel slab further comprises: 
 2.3% or less of Ni on a mass percentage basis.    
     
     
         14 . The method according to  claim 9 , wherein the steel slab further comprises: 
 about 0.50% or more to 2.3% or less of Ni on a mass percentage basis.    
     
     
         15 . The method according to  claim 9 , wherein the steel slab further comprises at least one of: 
 0.01% or less of Ca;    0.005% or less of B;    0.1% or less of Cr;    0.1% or less of Cu; and    0.1% or less of Mo,    on a mass percentage basis.    
     
     
         16 . The method according to  claim 10 , wherein the steel slab further comprises: 
 at least one of Sb and Sn in a total amount of 0.40% or less on a mass percentage basis.    
     
     
         17 . The method according to  claim 10 , wherein the steel slab comprises: 
 about 0.50% or more to 1.0% or less of Ni on a mass percentage basis.    
     
     
         18 . The method according to  claim 10 , wherein the steel slab further comprises at least one of: 
 0.01% or less of Ca;    0.005% or less of B;    0.1% or less of Cr;    0.1% or less of Cu; and    0.1% or less of Mo,    on a mass percentage basis.    
     
     
         19 . A method for manufacturing a non-oriented electrical steel sheet comprising: 
 hot-rolling a steel slab containing: 
 0-0.010% of C;  
 at least one of Si and Al in a total amount of 0.03% to 0.5%;  
 0.5% or less of Mn;  
 0.10% or more to 0.26% or less of P;  
 0.015% or less of S; and  
 0.010% or less of N, on a mass percentage basis,  
 Ni content is more than 1.0% to 2.3% by mass or less, and  
 the remainder being Fe and unavoidable impurities,  
   under conditions of a heating temperature in a single-phase austenite region and a coiling temperature of 650° C. or less;    annealing the hot-rolled sheet at a temperature of more than the A c3  transformation point in the single-phase austenite region;    descaling the annealed sheet to cold-roll the descaled sheet once or twice or more with an intermediate annealing sub-step therebetween; and then    finishing-annealing the cold-rolled sheet at a temperature of 700° C. or more in a single-phase ferrite region.    
     
     
         20 . The method according to  claim 19 , wherein the steel slab further comprises: 
 at least one of Sb and Sn in a total amount of 0.40% or less on a mass percentage basis.    
     
     
         21 . The method according to  claim 19 , wherein the steel slab further comprises at least one of: 
 0.01% or less of Ca;    0.005% or less of B;    0.1% or less of Cr;    0.1% or less of Cu; and    0.1% or less of Mo,    on a mass percentage basis.    
     
     
         22 . The method according to  claim 11 , wherein the steel slab further comprises: 
 at least one of Sb and Sn in a total amount of 0.40% or less on a mass percentage basis.    
     
     
         23 . The method according to  claim 11 , wherein the steel slab comprises: 
 about 0.50% or more to 2.3% or less of Ni on a mass percentage basis.    
     
     
         24 . The method according to  claim 11 , wherein the steel slab further comprises at least one of: 
 0.01% or less of Ca;    0.005% or less of B;    0.1% or less of Cr;    0.1% or less of Cu; and    0.1% or less of Mo,    on a mass percentage basis.