DIRECTIONAL MAGNETIC STEEL PLATE AND PRODUCTION METHOD THEREFOR

摘要

The present invention can provide a directional magnetic steel plate capable of further reducing iron loss of a material with a groove formed thereon for dividing a magnetic domain and capable of obtaining excellent low-iron-loss characteristics when incorporated into an actual transformer. This directional magnetic steel plate is obtained under the following conditions: the thickness of a forsterite coating at the bottom of a groove formed on the surface of the steel plate is 0.3 µm or more; the groove frequency which is the abundance ratio of grooves having, immediately thereunder, crystal grains with an orientation 10° or more different from the Goss orientation and a grain size of 5 µm or more is 20% or less; the total tension to be applied to the steel plate by the forsterite coating and a tension coating is 10.0 MPa or more in the rolling direction and 5.0 MPa or more in the direction perpendicular to the rolling direction; and these total tensions satisfy the relationship of formula, 1.0 = A/B = 5.0 where A is the total tension applied in the rolling direction by the forsterite coating and the tension coating, and B is the total tension applied in the direction perpendicular to the rolling direction by the forsterite coating and the tension coating.