| 摘要 |
PROBLEM TO BE SOLVED: To provide a steel sheet which is formed by hydroforming at low cost without undergoing heat treatment before hydroforming and diameter reducing rolling for hydroforming particularly appropriately used as a raw material for, for example, structural members, chassis members, etc., of a car body. SOLUTION: The steel sheet for hydroforming has a composition consisting of 0.02 to 0.2% C, 0.005 to 1.0% Si, 0.1 to 3.0% Mn, 0.005 to 0.1% P,≤0.01% S, 0.005 to 1.0% Al, 0.0005 to 0.01% N, and 0.01 to 0.2% Ti and/or 0.01 to 0.2% Nb, and if necessary consists of 0.5 V and/or 0.5% Mo, and/or 0.01% Ca, and/or 0.01% Mg and the balance Fe and inevitable impurities, in which the ferrite phase of 1.1 to 10μm in average grain size and 0.3 to≤3 in average aspect ratio is 60 to 98%, [the tensile strength TS (MPa) in the rolling direction]×[monoaxial tensile total elongation EL (%)] is≥14,000 (MPa%), and [the tensile strength (MPa) in the transverse direction of the sheet]×[monoaxial tensile uniform elongation UEL (%)] is≥7,000 (MPa%). COPYRIGHT: (C)2008,JPO&INPIT
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