Extremely thin production manner and the pole of the silicon steel sheet it is thin silicon steel sheet

摘要

PROBLEM TO BE SOLVED: To manufacture an extra thin silicon steel sheet with high magnetic flux density by executing specific cold rolling and multistage annealing after specific annealing on a hot rolled steel plate with specific composition containing C, Si, Mn, P, S, Al, N and impurities. ;SOLUTION: A hot rolled steel plate containing, by weight, ≤0.01% C, 2.5-7.0% Si, 0.005-0.12% Mn, ≤0.02% P, 0.002-0.005% S, 0.0015-0.006% sol. Al, 0.001-0.008% N and ≤0.003% Ti + Nb as impurities is annealed on condition indicated by a relation (T: annealing temp. in °C, t: holding time in min, R: temp. rising rate in °C/min). This steel plate is, after descaling, made into ≤0.20mm thickness through two or three times cold rolling including intermediate annealing with ≥0.1°C/sec heating/cooling velocity and 0.5-10min holding time. This cold rolled steel sheet goes through primary and secondary annealing including heating and holding at 700-1000°C under a reducing atmosphere of ≥50vol.% N₂, and then tertiary annealing including heating and holding at 900-1300°C under a reducing or nonoxidizing atmosphere without N₂ or under vacuum.;COPYRIGHT: (C)1998,JPO