Grain oriented electromagnetic steel sheet exhibiting extremely small watt loss and method for producing the same

摘要

The present invention relates to a grain-oriented magnetic steel sheet having extremely low iron loss, which is suitable for use as an iron core material for transformers and power generators, and to a method for producing the same. That is, in accordance with the present invention, a method for producing a grain-oriented magnetic steel sheet includes the step of forming a coating layer on a surface of the matrix of a steel sheet having a thickness of 0.27 mm or less by vapor deposition in a low oxidizing atmosphere with an oxygen partial pressure (Po2) of less than 0.1 atm and a total pressure of 0.1 atm or more. A grain-oriented magnetic steel sheet of the present invention having extremely low iron loss with a thickness of 0.27 mm or less includes a coating layer formed by vapor deposition on a matrix surface. The coating layer is composed of a material that has a smaller coefficient of thermal expansion than that of iron, the coating layer has a porosity of 10% or less and a mean thickness of not less than 0.1 mum and not more than 10 mum and the surface of the coating layer has a centerline mean roughness (Ra) of less than 0.5 mum.