METHOD FOR PRODUCING NONORIENTED SILICON STEEL SHEET HAVING EXCELLENT CORE LOSS AND BRITTLENESS CHARACTERISTIC

摘要

PROBLEM TO BE SOLVED: To provide a method for producing a nonoriented silicon steel sheet which has excellent core loss, brittle characteristics and productivity. ;SOLUTION: A hot rolled steel sheet having a composition containing, by mass, ≤0.003% C, 2.0 to 4.5% Si, 0.1 to 3.0% Al, 0.07 to 3% Mn, ≤0.05% P, ≤0.002% S, ≤0.003% N and ≤0.004% O, and the balance inevitable components is subjected to continuous hot rolled sheet annealing, and then is subjected to cold rolling and recrystallization annealing to produce the nonoriented silicon steel sheet having excellent core loss and brittle characteristics. In a cooling step in the continuous hot rolled sheet annealing, the primary cooling rate to a holding temperature of ≥450°C is controlled to ≤100°C/sec, and the steel sheet is held at the above holding temperature for ≥30 sec, and after that, the secondary cooling rate from the above holding temperature is controlled to ≤50°C/sec.;COPYRIGHT: (C)2003,JPO