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

Abstract

The present invention provides a non-oriented electrical steel sheet at low cost that has excellent magnetic properties and mechanical properties as well as excellent quality of steel sheet. The non-oriented electrical steel sheet has a chemical composition containing, by mass %, Si: 5.0% or less, Mn: 2.0% or less, Al: 2.0% or less, and P: 0.05% or less, in a range satisfying formula (1), and furthermore, C: 0.008% or more and 0.040% or less; N: 0.003% or less, and Ti: 0.04% or less, in a range satisfying formula (2), with the balance composed of Fe and incidental impurities: 300≦85[Si %]+16[Mn %]+40[Al %]+490[P %]≦430  (1) 0.008≦Ti*<1.2[C %]  (2), where Ti*=Ti−3.4[N %].

1 . A non-oriented electrical steel sheet comprising, by mass %:
 Si: 5.0% or less;   Mn: 2.0% or less;   Al: 2.0% or less; and   P: 0.05% or less,   
       in a range satisfying formula (1), and the steel sheet further comprising, by mass %:
 C: 0.008% or more and 0.040% or less; 
 N: 0.003% or less; and 
 Ti: 0.04% or less, 
 
       in a range satisfying formula (2), the balance being composed of Fe and incidental impurities:
   300≦85[Si %]+16[Mn %]+40[AI %]+490[P %]≦430  (1)
 
   0.008≦Ti*<1.2[C %]  (2),
 
 where Ti*=Ti−3.4[N %]. 
 
     
     
         2 . The non-oriented electrical steel sheet according to  claim 1 , wherein the Si, Mn, Al and P contents are, by mass %,
 Si: more than 3.5% but not more than 5.0%,   Mn: 0.3% or less,   Al: 0.1% or less, and   P: 0.05% or less.   
     
     
         3 . The non-oriented electrical steel sheet according to  claim 1 , further comprising, by mass %, at least one of:
 Sb: 0.0005% or more and 0.1% or less;   Sn: 0.0005% or more and 0.1% or less;   B: 0.0005% or more and 0.01% or less;   Ca: 0.001% or more and 0.01% or less;   REM: 0.001% or more and 0.01% or less;   Co: 0.05% or more and 5% or less;   Ni: 0.05% or more and 5% or less; and   Cu: 0.2% or more and 4% or less.   
     
     
         4 . A method for manufacturing a non-oriented electrical steel sheet, comprising:
 subjecting a steel slab to soaking, where the steel slab is retained at a soaking temperature of 1000° C. to 1200° C., the steel slab containing, by mass %,   Si: 5.0% or less,   Mn: 2.0% or less,   Al: 2.0% or less, and   P: 0.05% or less,   
       in a range satisfying formula (1), and the steel slab further containing, by mass %,
 C: 0.008% or more and 0.040% or less, 
 N: 0.003% or less, and 
 Ti: 0.04% or less, 
 
       in a range satisfying formula (2);
 subjecting the steel slab to subsequent hot rolling to obtain a hot-rolled steel material; 
 then subjecting the steel material to cold rolling or warm rolling once, or twice or more with intermediate annealing performed therebetween, to be finished to a final sheet thickness; and 
 subjecting the steel material to final annealing, wherein prior to the final annealing, the steel material is subjected to heat treatment at least once where the steel material is retained at temperatures of 800° C. or higher and 950° C. or lower for 30 seconds or more, and subsequently to the final annealing at 700° C. or higher and 850° C. or lower:
   300≦85[Si %]+16[Mn %]+40[Al %]+490[P %]≦ 430   (1)
 
   0.008≦Ti*<1.2[C %]  (2),
 
 
 where Ti*=Ti−3.4[N %]. 
 
     
     
         5 . The method for manufacturing a non-oriented electrical steel sheet according to  claim 4 , wherein the Si, Mn, Al and P contents are, by mass %,
 Si: more than 3.5% but not more than 5.0%,   Mn: 0.3% or less,   Al: 0.1% or less, and   P: 0.05% or less.   
     
     
         6 . The method for manufacturing a non-oriented electrical steel sheet according to  claim 4 , wherein the steel slab further contains, by mass %, at least one of:
 Sb: 0.0005% or more and 0.1% or less,   Sn: 0.0005% or more and 0.1% or less,   B: 0.0005% or more and 0.01% or less,   Ca: 0.001% or more and 0.01% or less,   REM: 0.001% or more and 0.01% or less,   Co: 0.05% or more and 5% or less,   Ni: 0.05% or more and 5% or less, and   Cu: 0.2% or more and 4% or less.