Grain-oriented electrical steel sheet causing low core loss and low magnetostriction

1. A grain-oriented electrical steel sheet comprising:

a base steel sheet;

a primary film formed on a surface of the base steel sheet; and

a tension insulation coating formed on a surface of the primary film,

wherein a magnetic domain control is performed by irradiating the tension insulation coating with a laser from above,

wherein a value d t /d p obtained by dividing an average thickness d t of the tension insulation coating in the unit of μm by an average thickness d p of the primary film in the unit of μm is 0.1 or higher and 3.0 or lower, and

having a property wherein when a sample having a length of 300 mm in a direction parallel to a rolling direction of the grain-oriented electrical steel sheet and a length of 60 mm in a direction parallel to a transverse direction is extracted from the grain-oriented electrical steel sheet, a range from a surface of the tension insulation coating to a depth position of 5 μm toward the base steel sheet side from an interface between the base steel sheet and the primary film is removed by pickling at least one surface of the sample, and a warpage amount of the sample is thereafter measured, the warpage amount satisfies the following expressions A and B

15000 μm≤ S A −S C ≤35000 μm  (Expression A)

900 μm≤ S B +S C ≤14000 μm  (Expression B)

wherein

S A is a warpage amount of the grain-oriented electrical steel sheet in the unit of μm when only one surface subjected to laser irradiation is pickled,

S B is a warpage amount of the grain-oriented electrical steel sheet in the unit of μm when only one surface on a side opposite to the side subjected to laser irradiation is pickled, and

S C is a warpage amount of the grain-oriented electrical steel sheet in the unit of μm when both surfaces are pickled,

wherein warpage in the same direction as that of the pickled surface during measurement of S A and S B is expressed as a positive value, and warpage in S C in the same direction as that of S A is expressed as a positive value.

2. The grain-oriented electrical steel sheet according to claim 1 ,

wherein a value d t /d p obtained by dividing an average thickness d t of the tension insulation coating in the unit of μm by an average thickness d p of the primary film in the unit of μm is 0.1 or higher and 1.5 or lower.

3. The grain-oriented electrical steel sheet according to claim 1 ,

wherein a value d t /d p obtained by dividing an average thickness d t of the tension insulation coating in the unit of μm by an average thickness d p of the primary film in the unit of μm is 0.1 or higher and 1.0 or lower.

4. The grain-oriented electrical steel sheet according to any one of claims 1 , 2 and 3 ,

wherein the average thickness of the tension insulation coating is 0.5 μm or greater and 4.5 μm or smaller.

5. The grain-oriented electrical steel sheet according to any one of claims 1 , 2 and 3 ,

wherein a total tension applied to the base steel sheet from the primary film and the tension insulation coating is 1 MPa or higher and 10 MPa or lower.

6. The grain-oriented electrical steel sheet according to claim 4 ,

wherein a total tension applied to the base steel sheet from the primary film and the tension insulation coating is 1 MPa or higher and 10 MPa or lower.

7. The grain-oriented electrical steel sheet according to claim 1 ,

wherein the laser is irradiated at an irradiation energy density of 0.8 mJ/mm 2 to 2.0 mJ/mm 2 .