Non-oriented magnetic steel sheet and method for producing the same
View Patent ↗A non-oriented magnetic steel sheet contains, by mass %, C: 0.005% or less; Si: 2% to 4%; Mn and V: totally 11% or less; and Al: 3% or less, with the balance being Fe and inevitable impurities, wherein a Mn concentration (mass %) and a V concentration (mass %) in a thickness direction satisfy the following formula. 0.1<(Xs Mn,V −Xc Mn,V )/t Mn,V <100, where Xs Mn,V : a sum of the Mn concentration (mass %) and the V concentration (mass %) at a surface of the steel sheet, Xc Mn,V : a sum of the Mn concentration (mass %) and the V concentration (mass %) at a center of the steel sheet, and t Mn,V : a depth (mm), from the surface of the steel sheet, of a position where the sum of the Mn concentration (mass %) and the V concentration (mass %) is equal to Xc Mn,V .
1. A method for producing a non-oriented magnetic steel sheet comprising:
annealing a hot-rolled steel sheet containing, by mass %, C: 0.005% or less; Si: 2% to 4%; Mn: 1% or less; and Al: 3% or less, with the balance being Fe and inevitable impurities, so as to obtain an annealed hot-rolled steel sheet;
cold-rolling the annealed hot-rolled steel sheet so as to obtain a cold-rolled steel sheet;
plating a surface of the cold-rolled steel sheet with V so as to obtain a plated cold-rolled steel sheet; and
subsequently annealing the plated cold-rolled steel sheet at a temperature between 900°C and 1000°C for one hour or more.
2. The method for producing a non-oriented magnetic steel sheet according to claim 1 , wherein, by the annealing the plated cold-rolled steel sheet, a V concentration (mass %) in a thickness direction of the non-oriented magnetic steel sheet is made to satisfy the following formula:
0.1<( Xs V −Xc V )/ t V <100,
where
Xs V : the V concentration (mass %) at a surface of the steel sheet,
Xc V : the V concentration (mass %) at a center of the steel sheet, and
t V : a depth (mm), from the surface of the steel sheet, of a position where the V concentration (mass %) is equal to Xc V .
3. The method for producing a non-oriented magnetic steel sheet according to claim 1 , wherein, by the annealing the plated cold-rolled steel sheet, a V concentration (mass %) in a thickness direction of the non-oriented magnetic steel sheet is made to satisfy the following formula:
0.1<( Xs V ′−Xc V )/ t V <100,
where
Xs V ′: a maximum value of the V concentration (mass %) in a surface region,
Xc V : the V concentration (mass %) at a center of the steel sheet, and
t V : a depth (mm), from the surface of the steel sheet, of a position where the V concentration (mass %) is equal to Xc V , and
the surface region is a region with a thickness of 5 μm from the surface of the steel sheet.
4. The method for producing a non-oriented magnetic steel sheet according to claim 1 , wherein a V concentration of the plated cold-rolled sheet is 0.34mass % or more.
5. A method for producing a non-oriented magnetic steel sheet comprising:
annealing a hot-rolled steel sheet containing, by mass %, C: 0.005% or less; Si: 2% to 4%; Mn: 1% or less; and Al: 3% or less, with the balance being Fe and inevitable impurities, so as to obtain an annealed hot-rolled steel sheet;
plating a surface of the annealed hot-rolled steel sheet with V so as to obtain a plated hot-rolled steel sheet;
cold-rolling the plated hot-rolled steel sheet so as to obtain a plated cold-rolled steel sheet; and
subsequently annealing the plated cold-rolled steel sheet at a temperature between 900°C and 1000°C for one hour or more.
6. The method for producing a non-oriented magnetic steel sheet according to claim 5 , wherein, by the annealing the plated cold-rolled steel sheet, a V concentration (mass %) in a thickness direction of the non-oriented magnetic steel sheet is made to satisfy the following formula:
0.1<( Xs V −Xc V )/ t V <100,
where
Xs V : the V concentration (mass %) at a surface of the steel sheet,
Xc V : the V concentration (mass %) at a center of the steel sheet, and
t V : a depth (mm), from the surface of the steel sheet, of a position where the V concentration (mass %) is equal to Xc V .
7. The method for producing a non-oriented magnetic steel sheet according to claim 5 , wherein, by the annealing of the plated cold-rolled steel sheet, a V concentration (mass %) in a thickness direction of the non-oriented magnetic steel sheet is made to satisfy the following formula:
0.1<( Xs V ′−Xc V )/ t V <100,
where
Xs V ′: a maximum value of the V concentration (mass %) in a surface region,
Xc V : the V concentration (mass %) at a center of the steel sheet, and
t V : a depth (mm), from the surface of the steel sheet, of a position where the V concentration (mass %) is equal to Xc V , and
the surface region is a region with a thickness of 5 μm from the surface of the steel sheet.
8. The method for producing a non-oriented magnetic steel sheet according to claim 5 , wherein a V concentration of the plated cold-rolled sheet is 0.34mass % or more.