HIGH STRENGTH STEEL SHEET FOR EXPLOSION-PROOF BAND HAVING EXCELLENT WELDABILITY AND MAGNETIC PROPERTY, AND HAVING REDUCED DETERIORATION IN MAGNETIC PROPERTY WITH LAPSE OF TIME

摘要

PROBLEM TO BE SOLVED: To provide a high strength steel sheet for an explosion-proof band which has excellent weldability and magnetic properties, and has reduced deterioration in the magnetic properties with the lapse of time.;SOLUTION: The steel sheet has a composition comprising, by mass, 0.001 to 0.2% C, 0.2 to 1% Si, 0.5 to 2.3% Mn, 0.02 to 0.15% P, ≤0.005% O, ≤0.03% S and ≤0.01% N, and in which the segregation ratio of P expressed by (Pmax-Pave)×100/Pave (wherein, Pmax denotes the maximum P concentration in the steel sheet; and Pave denotes the average P concentration in the steel sheet) is ≤100%, and the average crystal grain size of ferrite is 5 to 25 μm. Its non-hysteresis permeability after heating at 500°C for 60 s is ≥7,000, and the aging index AI thereof is ≤90 N/mm².;COPYRIGHT: (C)2005,JPO&NCIPI