| 摘要 |
PROBLEM TO BE SOLVED: To obtain a uniform forsterite film free from defects over the whole face of a coil and excellent in adhesion by making the amt. of Cr included as impurities in a base stock to a specified value or below, regulating the atmospheric oxidizability at the time of decarburizing, annealing and soaking to a specified range and making subscale form in which the coating weight of oxygen is a specified value on the surface layer of a steel sheet after decarburizing and annealing. SOLUTION: A silicon steel slab as a base stock contains, by weight, 0.03 to 0.12% C, 2.0 to 4.5% Si, 0.01 to 0.05% sol. Al and 0.004 to 0.012% N. The content of impurity Cr included in this base stock is made to <=0.05%. Then, the atmospheric oxideizability expressed by P(H2 O)/P(H2 ) in the case of decarburizing, annealing and soaking is regulated to the range of formula: 0.35-2x<=y<=0.60-2x in which (y) is decided by the Cr content and (x) is (wt.%) and subscale in which the coating weight of oxygen is 0.35 to 0.75 g/m<2> per the one side, is formed on the surface of the steel sheet after decarburizing and annealing. |
