Non-oriented electrical steel sheet and manufacturing method thereof

1. A non-oriented electrical steel sheet, containing:

Si: not less than 1.0 mass % nor more than 3.5 mass %;

Al: not less than 0.1 mass % nor more than 3.0 mass %;

Mn: not less than 0.1 mass % nor more than 2.0 mass %;

Ti: not less than 0.001 mass % nor more than 0.01 mass %; and

Bi: not less than 0.001 mass % nor more than 0.01 mass %,

a C content being 0.01 mass % or less,

a P content being 0.1 mass % or less,

a S content being 0.005 mass % or less,

a N content being 0.005 mass % or less, and

a balance being composed of Fe and inevitable impurities, wherein:

a Ti content (mass %) is represented as [Ti] and a Bi content (mass %) is represented as [Bi], and Expression (1) below is satisfied:

[Ti]≦0.8×[Bi]+0.002  Expression (1),

wherein a number of TIN or TiS pieces having an equivalent spherical diameter of 0.01 μm to 0.05 μm is less than 1×10 8 per 1 mm 3 of the non-oriented electrical steel sheet.

2. The non-oriented electrical steel sheet according to claim 1 , wherein Expression (2) below is further satisfied:

[Ti]≦0.65×[Bi]+0.0015  Expression (2).

3. The non-oriented electrical steel sheet according to claim 1 , further containing at least one selected from the group consisting of Cu: 0.5 mass % or less and Cr: 20 mass % or less.

4. The non-oriented electrical steel sheet according to claim 1 , further containing at least one selected from the group consisting of Sn and Sb being 0.3 mass % or less in total.

5. The non-oriented electrical steel sheet according to claim 1 , further containing Ni: 1.0 mass % or less.

6. A non-oriented electrical steel sheet, containing:

Si: not less than 1.0 mass % nor more than 3.5 mass %;

Al: not less than 0.1 mass % nor more than 3.0 mass %;

Mn: not less than 0.1 mass % nor more than 2.0 mass %;

Ti: not less than 0.001 mass % nor more than 0.01 mass %;

Bi: not less than 0.001 mass % nor more than 0.01 mass %; and

at least one selected from a group consisting of REM and Ca,

a C content being 0.01 mass % or less,

a P content being 0.1 mass % or less,

a S content being 0.01 mass % or less,

a N content being 0.005 mass % or less, and

a balance being composed of Fe and inevitable impurities, wherein:

a Ti content (mass %) is represented as [Ti] and a Bi content (mass %) is represented as [Bi], and Expression (1) below is satisfied, and

the S content (mass %) is represented as [S], a REM content (mass %) is represented as [REM], and a Ca content (mass %) is represented as [Ca], and Expression (3) below is satisfied:

[Ti]≦0.8×[Bi]+0.002  Expression (1)

[S]−(0.23×[REM]+0.4×[Ca])≦0.005  Expression (3),

wherein a number of TiN or TiS pieces having an equivalent spherical diameter of 0.01 μm to 0.05 μm is less than 1×10 8 per 1 mm 3 of the non-oriented electrical steel sheet.

7. The non-oriented electrical steel sheet according to claim 6 , further containing at least one selected from the group consisting of Cu: 0.5 mass % or less and Cr: 20 mass % or less.

8. The non-oriented electrical steel sheet according to claim 6 , further containing at least one selected from the group consisting of Sn and Sb being 0.3 mass % or less in total.

9. The non-oriented electrical steel sheet according to claim 6 , further containing Ni: 1.0 mass % or less.

10. A non-oriented electrical steel sheet, consisting of;

Si: not less than 1.0 mass % nor more than 3.5 mass %;

Al: not less than 0.1 mass % nor more than 3.0 mass %;

Mn: not less than 0.1 mass % nor more than 2.0 mass %;

Ti: not less than 0.001 mass % nor more than 0.01 mass %;

Bi: not less than 0.001 mass % nor more than 0.01 mass %,

C: 0.01 mass % or less,

P: 0.1 mass % or less,

S: 0.005 mass % or less,

N: 0.005 mass % or less, and

a balance of Fe and inevitable impurities,

wherein the steel sheet satisfies Expression (1):

[Ti]≦0.8×[Bi]+0.002  Expression (1),

wherein [Ti] represents a Ti content (mass %), and [Bi] represents a Bi content (mass %),

wherein a number of TiN or TiS pieces having an equivalent spherical diameter of 0.01 μm to 0.05 μm is less than 1×10 8 per 1 mm 3 of the non-oriented electrical steel sheet.