| 摘要 |
PURPOSE:To produce the silicon steel sheet having excellent magnetic characteristics by subjecting a cold rolled silicon steel sheet contg. specific ratios of C and N to weak decarburizing and denitrizing, then further to annealing in the decarburizing and denitrizing atmosphere. CONSTITUTION:The cold rolled silicon steel sheet which contains, by weight %, 0.2-6.5% Si, >=0.005% Nb, >=0.03% C+N or further contains one or >=2 kinds of <=4.0% Mn, <=3.0% Al, and <=1.0% Co is annealed in a vacuum or the weak decarburizing and denitrizing atmosphere of an inert gas, CO, CO2, H2, etc., in the two phase region of alpha-ferrite+austenite or the single phase region of austenite and in the temp. region where the alpha-austenite alone is formed when C and N are removed. The surface layer part is decarburized and denitrized by this annealing, by which the single phase of the alpha-austenite is formed and the two phases of the alpha-ferrite+austenite or the single phase of the alpha-austenite still remains in the inside. The steel sheet is subjected to the strong decarburizing and denitrizing annealing so as to attain <=0.01% C+N in gaseous H2 to integrate the <100> axes at a high rate to the steel sheet surface to form the columnar grain structure of the alpha-ferrite phase. The silicon steel sheet having the excellent magnetic characteristics as the magnetic core of a transformer, etc., is thus obtd. |
