| 摘要 |
PROBLEM TO BE SOLVED: To produce excellent steel for a magnetic shielding structure provided with homogeneous and stable high permeability, strength and toughness and to provide a method for producing a thick steel plate thereof. SOLUTION: This steel for a magnetic shielding structure is the one which has a compsn. contg., by weight, <=0.007% C, 0.5 to 2% Si, <=1.5% Mn, <=0.05% P, <=0.005% S, 0.2 to 0.8% Cu, 0.3 to 1.5% Ni, 1 to 3% Cr, 0.2 to 0.8% Al, <=0.007% N, and the balance Fe with inevitable impurities, has a ferrite single phase structure, and in which crystal grain size is controlled to 150 to 300 μm. Moreover, as to the method for producing a thick steel plate, a slab having the above componential compsn. is heated at >=Ac3 point, is rolled in such a manner that the draft at <=Ar3 temp. is controlled to 20 to 40%, and the rolling finishing temp. is controlled to Ar1-20 deg.C to Ar1-50 deg.C and is subjected to heat treatment of holding it at 800 to 930 deg.C also in the range of (the heat treating temp. THT calculated by the following formula ±25 deg.C) for >=120 min: the formula: THT=800+0.74×(Ac1-850) ( deg.C). |
