| 摘要 |
PROBLEM TO BE SOLVED: To realize a high-strength steel sheet superior in formability, and a manufacturing method therefor on an industrial scale. SOLUTION: This steel sheet comprises, by mass%, 0.03-0.20% C, 0.005-0.3% Si, 1.0-3.1% Mn, 0.001-0.06% P, 0.001-0.01% S, 0.0005-0.01% N, 0.2-1.2% Al, 0.5% or less Mo and the balance Fe with unavoidable impurities, while controlling Si, Mn and Al so as to satisfy the following expressions (A) and (B): (A): (0.0012×[TS target value]-0.29-[Si])/2.45<Al<1.5-3×[Si], wherein [TS target value] is a designed value for the strength of the steel sheet expressed by the unit of MPa; and [Si] is the mass of Si by percentage; and (B): 500×[B]+[Mn]+0.2[Al]<2.9, wherein [B] is the mass of B by percentage, [Mn] of Mn, and [Al] of Al. The steel sheet has a metallographic structure containing ferrite and martensite. COPYRIGHT: (C)2005,JPO&NCIPI |
