| 摘要 |
PURPOSE:To effectively suppress the increase of the iron loss of the titled steel sheet, by controlling the temp. of stress-relief annealing on the basis of the total value of analyzed S and Se contents in a finally finished steel sheet including a forsterite film. CONSTITUTION:The blank sheet of silicon steel contg. S or Se is hot-rolled and then cold-rolled in accompany with intermediate annealing into a cold-rolled steel sheet having final thickness. Thereafter, the cold-rolled steel sheet is annealed with decarburization, MgO is applied to the surface of the steel sheet, and then the steel sheet is finally finish annealed. In succession, a phosphate film is formed on a forsterite film formed on the surface of the finally finished steel by a coating treatment, to make the unidirectional silicon steel sheet. When the coated steel sheet is worked and strain-relief annealed in the following, the temp. of annealing is controlled on the basis of the total value of analyzed S and Se contents in the finally finished steel sheet including the forsterite film to prevent the invasion of S and Se into the steel substrate. Consequently, the increase of an iron loss is effectively suppressed. |
