To provide a low-yield-ratio steel sheet having superior Young's modulus in a rolling direction.
The high-strength steel sheet having high Young's modulus and adequate press formability comprises 0.05 to 0.30% C, 0.1 to 5.0% Mn, 0.15% or less P, 0.015% or less S, 0.01% or less N, one or both of Si and Al in a total amount of 0.15 to 3.0%, one or more elements among 0.01 to 1.5% Mo, 0.005 to 0.20% Nb, 48/14×N[mass%] to 0.2% Ti and 0.0001 to 0.01% B, in a total amount of 0.015 to 1.91 mass%, and the balance iron with unavoidable impurities; is a dual-phase steel sheet including ferrite or bainite as the largest structure by volume fraction, and 3 to 20% retained austenite by volume fraction; has poles of ä110}<223> and ä110}<111> so that one or both of the pole density can satisfy 10 or more, in a layer 1/8 deep from the surface in a sheet thicknesses direction; and has Young's modulus of more than 230 GPa in a rolling direction.
COPYRIGHT: (C)2008,JPO&INPIT
SUGIURA NATSUKO
TAKAHASHI MANABU
| WO2006011503A1 | 2006-02-02 |
Tadashi Takahashi
Masakazu Aoyama
Sumio Tanai
Dragon God Yoshihiko
Hiroshi Masui