PURPOSE: To provide a fullprocessed nonoriented silicon steel sheet having superior magnetic properties and weldability by applying a mixture film of inorganic matter and organic matter, in which components are specially regulated, to the surface of a steel sheet having a specific composition and regulating the surface roughness to a specific value.
CONSTITUTION: The steel has a composition consisting of ≤0.005% C, 0.05-1.0% Si, 0.1-1.5% Mn, ≤0.15% P, ≤0.01% S, 0.01-0.15% Sol.Al, ≤0.0050% N, B in the amount satisfying the relation in B/N=0.5 to 2.5, ≤0.02% T.0, and the balance Fe with inevitable impurities. A mixture film of inorganic matter and organic matter, which contains one or two kinds among phosphoric acid and chromic acid-based inorganic components and where components are regulated so that the content of organic resin becomes 50-400mg/m2, is applied to the surface of a sheet of the above-mentioned steel and surface roughness Ra is regulated to 0.25μm. By this method, the silicon steel sheet having superior blankability and space factor can be provided.
HIROSE KIKUJI
KONO ROKURO
OGA MASATAKA
UEMURA TOSHIHIKO
