[Document Type] Specification [Title of the Invention] GRAIN-ORIENTED ELECTRICAL STEEL SHEET CAUSING LOW CORE LOSS AND LOW MAGNETOSTRICTION [Technical Field of the Invention] [0001] The present invention relates to a grain-oriented electrical steel sheet used in the core of a transformer or the lik~, and more particularly, to a grain-oriented electrical steel sheet which contributes to a reduction in noise as well as a reduction in core loss of a core and causes low core loss and low magnetostriction. '1 i Priority is claimed on Japanese Patent Application No. 2014-97685, filed on May 9, 2014, the content of which is incorporated herein by reference. [Related Art] [0002] _ _,_,.-, A grain-oriented electrical steel sheet is generally used in a stationary induction apparatus represented by a transformer. Characteristics to be satisfied by the grain-oriented electrical steel sheet include low core loss, ease of excitation, low magnetostriction, and the like. A transformer is continuously excited over a long period of time from installation to disuse and thus continuously generates energy losses. Due to these . characteristics, low core loss is particularly required. [0003] In order to reduce the core losses of a grain-oriented electrical steel sheet, core losses have been improved by metallurgical methods such as increasing the degree of integration along a (11 0) [001] orientation called the Goss orientation, reducing the amount of impurities in a steel sheet product, reducing the size of grains, and applying - 1 - OSP-64414(IN)(EN-Specification) a coating that imparts surface tension to a steel sheet. However, these methods have limitations, and a reduction in core loss using other methods is required. [0004] For such a problem, a method of refining magnetic domains themselves has been '.' developed. Currently, a teclmique of irradiating the surface of a steel sheet with a laser to introduce strain into the steel sheet and reducing the widths of magnetic domains thereby reducing the core loss has been widely used. [0005] As described above, core loss of a grain-oriented electrical steel sheet has been significantly improved. On the other hand, a reduction in noise and vibration is further required by apparatuses for electromagnetic application such as a transformer. Therefore, a grain-oriented electrical steel sheet used in the core of a transformer also requires low magnetostriction as well as low core loss. [0006] Laser irradiation for reducing core losses causes the introduction of residual strain and is effective in refining magnetic domain widths. However, it is known that laser irradiation becomes a source of magnetostriction. Therefore, techniques in which, when magnetic domain control is performed by irradiating a grain-oriented electrical steel sheet, on which a coating is formed, with a laser, magnetostriction is reduced by adjusting laser irradiation conditions and film tension, thereby allowing low core loss and low magnetostriction to be compatible with each other are disclosed in Patent Documents I to 4. [0007] Patent Document 1 discloses th~t as factors for determining magnetostriction, the tension of a primary film, the tension of a tension insulation coating, and the - 2 - OSP-64414(IN)(EN-Specification) application of micro-strain through laser irradiation are very important, and by controlling these factors, a grain-oriented electrical steel sheet which has magnetostriction characteristics for low noise and causes low core loss can be provided. Patent Document I discloses that pulse laser irradiation was performed to cause the total tension of th'e' 'p rimary film and a secondary coating applied thereafter on a steel sheet to be I MPa to 8 MPa and cause the amount of heat input per unit area of the steel sheet to be 1 mJ/mm2 to 2 rnJ/mm2 , otherwise the pulse laser irradiation being performed to cause the tension to be 14 MPa or higher and the amount of heat input to be 1.5 mJ/mm2 to 3 mJ/mm2 . ' I [0008] Patent Document 2 discloses a grain-oriented electrical steel sheet having a forsterite film and a tension coating, in which, in order to prevent the deterioration of magnetostriction characteristics due to damage to the coatings in a case where magnetic domain refinement is performed through laser irradiation, the total tension A applied to the steel sheet in a rolling direction from the forsterite film and the tension coating is 10.0 MPa or higher, the total tension B in a direction perpendicular to the rolling direction is 5.0 MPa or higher, and the ratio AlB between the total tensions A and Bisset to 1.0 to 5.0. [0009] Patent Document 3 discloses a technique in which, when magnetic domain control is performed by irradiating a grain-oriented electrical steel sheet with a laser, the thickness of a solidified layer of a laser irradiated portion is set to 4 JJ.m at the maximum to cause strain to be introduced only into a narrow range in a rolling direction, thereby reducing core losses and simultaneously suppressing magnetostrictive deformation. - 3 - OSP-64414(1N)(EN -Specification) [OQIO] Patent Document 4 discloses a technique in which, before laser irradiation is performed on a grain-oriented electrical steel sheet, the amount of a primary film and the amount of a tension insulation coating are detected, and the laser irradiation is . , ' performed under appropriate irradiation conditions depending on the detected amounts, thereby reducing core losses and simultaneously reducing magnetostriction and noise in a transformer. [Prior Art Document] [Patent Document] • ' I [0011] [Patent Document 1] Japanese Unexamined Patent Application, First Publication No. 2002-356750 [Patent Document 2] Japanese Unexamined Patent Application, First Publication No. 2012-031498 [Patent Document 3] Japanese Unexamined Patent Application, First Publication No. 2007-002334 [Patent Document 4] Japanese Unexamined Patent Application, First Publication No. 2012-031519 [Disclosure of the Invention] . · [Problems to be Solved by the Invention] [0012] As described above, techniques in which, when magnetic domain control is performed by irradiating a grain-oriented electrical steel sheet, on which a coating is formed, with a laser, the film tension and laser irradiation conditions are adjusted and thus low core loss and low magnetostriction are allowed to be compatible with each - 4 - OSP -64414(IN)(EN -Specification) other have been disclosed. However, from the viewpoint of further enhancing magnetostriction characteristics in a state in which a high core loss reduction effect is maintained by laser irradiation, a further improvement is preferable. The present invention has been made taking the foregoing circumstances into consideration, and an objec't' t'h ereof is to provide a grain-oriented electrical steel sheet which allows low core loss and low magnetostriction to be compatible with each other. [Means for Solving the Problem] [0013] The core losses of a grain-oriented electrical steel sheet are reduced by minimizing the sum of eddy-current loss and hysteresis loss. In addition, the eddycurrent loss and the hysteresis loss are subjected to having complex variation with respect to various material parameters. In addition, the magnetostrictive deformation of the grain-oriented electrical steel sheet is also subjected to having complex variation with respect to various material parameters. For example, stress is applied to a base steel sheet by coatings (a tension insulation coating and a primary film (glass coating)) applied to a grain-oriented electrical steel sheet, and stress is applied to the base steel sheet also by laser irradiation for magnetic domain control. The inventors found that a range of stress applied due to film tension and a laser in which the core loss and the magnetostriction were minimized with a good balance was present depending on the degree of an effect of such a stress distribution. In addition, the inventors evaluated the stress according to variation in the warpage amount of a grain-oriented electrical steel sheet and found a range in which magnetostriction was optimized. [0014] - 5 - OSP-64414(TN)(EN-Specification) The gist of the present invention is as follows. ( 1) According to an aspect of the present invention, a grain-oriented electrical steel sheet includes: 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, in . •' which a magnetic domain control is perfmmed by irradiating the tension insulation coating with a laser from above. When a strip-like 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 ' ' I coating to a depth position of 5 f.!m 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 f.!m