| 摘要 |
PROBLEM TO BE SOLVED: To improve magnetic and coating properties over the whole width and whole length of a coil by prescribing the profile of a desiliconized layer to be formed before decarburizing annealing. SOLUTION: Tests lave revealed the following findings. In a state of a final cold rolled sheet, in a range of 1μm in sheet thickness direction from the surface, the ratio of the Si concn. to the Si concn. in the center part of the sheet thickness is regulated to <=0.90, and a desiliconizing layer is formed in the range of <=5μm from the surface as for the distance in the sheet thickness direction in which the Si concn. to the Si concn. in the center part of the sheet thickness is regulated to <=0.98. Then, the ratio P (H2 O)/P (H2 ) of the partial pressure of steam to the partial pressure of hydrogen in a soaking stage is regulated to <0.70, and P (H2 O)/P (H2 ) in a temp. rising state is made lower than that in the soaking stage. In this way, subscales having good physical properties can be obtd. As a result, the one having good magnetic properties and uniform forsterite insulating coating excellent in adhesion can be obtd. |
