| 摘要 |
PURPOSE:To produce an electrical plate for D.C. magnetic shielding excellent in magnetic shielding property by subjecting a thick plate of a low carbon steel containing small amounts of Ni to heat treatment under specific temp. conditions. CONSTITUTION:A slab of a steel having a composition consisting of, by weight, <0.05% C, >1.0-4.0% Si, <0.50% Mn, <0.005% solAl, 0.50-3.0% Ni, and the balance Fe is worked into plate-like state by means of hot casting or rolling and the resulting steel plate is heated up to a temp. region between the Ac3 transformation point of this steel and (Ac3 transformation point - 50 deg.C) and successively cooled slowly at 2.1 deg.C/min cooling rate, or, a slab of steel with the above composition is heated up to a temp. between the Ac3 transformation point and 1200 deg.C and hot casting or hot rolling is started and hot working is finished while regulating the reduction of area in a ferrite region to >=2 and, then, the resulting steel plate is heated up to a temp. region between the Ac3 transformation point and (Ac3 transformation point - 100 deg.C) and successively cooled slowly at 1.8 deg.C/min cooling rate. |
